AU2009311067B2

AU2009311067B2 - Master-slave mode direct current carrier communication system

Info

Publication number: AU2009311067B2
Application number: AU2009311067A
Authority: AU
Inventors: Huaping Lai; Fengguo Li; Xing Liu; Jinglong Yan; Xianyu Zhang
Original assignee: Beijing Ebtech Tech Co Ltd
Current assignee: Beijing Ebtech Tech Co Ltd
Priority date: 2008-11-07
Filing date: 2009-11-06
Publication date: 2014-02-13
Anticipated expiration: 2029-11-06
Also published as: AU2009311067A1; EA201100721A1; EA021702B1; ZA201104191B; WO2010051767A1

Abstract

The present invention provides a master machine and a slave machine in master-slave mode direct current carrier communication system. The master machine includes a master machine clock circuit, a master machine power supply system, a master machine communication interface and a master machine control module; the slave machine includes a slave machine communication interface, a rectifier bridge circuit, an energy storage module, a slave machine power supply system, a slave machine clock circuit and a slave machine control module. The master machine communication interface may be a single-polarity communication interface or a dual-polarity communication interface. The slave machine communication interface includes a slave machine data modulation module and a slave machine data demodulation module. The master machine implements data transmitting and data receiving under a communication voltage or two different communication voltages. Applying the solution above, bidirectional data exchange between the master machine and the slave machine is implemented when the master machine supplies electric power for the slave machine, and the connection of the master machine with the slave machine via a pair of non-polarity wires is also implemented. Therefore, the system maintainability and communication accuracy can be improved, and the designs of the master machine and the slave machine, and the connection between them are simplified. Therefore, the solution can be applied to the minitype slave machine system such as electronic detonator network and intelligent sensor network.

Description

Master-Slave Mode Direct Current Carrier Communication System Technical Field The present invention relates to the field of the communication, in particular to the improvements of the master machine and the slave machine in the master-slave mode direct current carrier communication system. Background of the Invention In the concentrated-distributed industry control system, industry field control buses such as PROFIBUS, LONWOKS, CAN and FF are used. The characteristic of such industry field control buses lies in that each distributed node needs a power supply system independent of the bus, and the data exchange can be realized normally only if the buses are connected in correct polarity. An electrical wire carrier communication system is often used in a carrier communication system at present. The master machine loads the data needed to be transmitted on the basic frequency electrical wire in the form of high frequency carrier, thereby the master machine can accomplish data transmission and power transmission to the slave machine of each node simultaneously. The characteristic of such system lies in that each slave machine of each node must include some specialized and complicated data modulation module and data demodulation module; and in order to receive the power and data simultaneously, the slave machine needs to extract the power supply for its self-operating in the form of transformer isolation, and then transform AC signal supplied by the external device to DC signal by using some methods such as commutating and filtering. In systems such as the electronic detonator network and the intelligent sensor network, the energy needed by the slave machine of each node is less, thereby it is convenient to supply operating power directly to the slave machine, which is beneficial to network maintenance; what is more, the slave machine is preferred to be in a smaller size. So the defects of systems such as the electronic detonator network or the intelligent sensor network in the form of the electrical wire carrier communication system mentioned above lie in: 1. The slave machine of each node should have a specialized module to receive and transmit data, which results in higher cost. 2. The mode of transmitting AC carrier will greatly increase the complexity of the slave power supply system. 3. The characters of modules included in the slave machine have great differences, for example, modules such as the isolation transformer will be hard to integrate. Considering the case mentioned above, the mode of DC carrier communication should be used to realize the communication between the master machine and the slave machine in the system such as the electronic network and the intelligent sensor network. The composition of the electronic detonator communication interface disclosed in Patent ZL200420115361.2, Patent ZL200420115363.1 and Patent ZL200420115362.7 has simplified the circuit structure, decreased the energy consumption of the slave machine during the process of data receiving, and improved the reliability of the slave machine with the communication speed maintaining high. But the following problems still exist in the above technical solution: 1. The data receiving circuit is realized by using resistors to divide voltage or voltage-regulator tubes to commutate, which results in a greater power consumption of the slave machine and increases the load of the master machine. 2. The communication interface is connected after the rectifier bridge, which does not apply to the system with dual-polarity data high speed transmission. The slave communication interface disclosed in Patent ZL200420084237.4 uses a specialized module to realize the function of receiving and transmitting data, but the integratability of such communication interface is poor, and it still can not meet the application demand of the minitype slave machine. Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application. Summary of the Invention The purpose of the present invention is to ameliorate solve the defects of the prior art described above, and to provide a master machine and a slave machine included in a master-slave mode direct current carrier communication system which is connected in the mode of double-wire non-polarity and can accomplish simplex and bidirectional data transmission while the master machine supplies direct current power to the slave machine. This technical 2 solution has furthest simplified the design and the connection of the master machine and the slave machine, rendering the master machine and the slave machine applicable to the minitype slave machine systems such as the electronic detonator network, the intelligent sensor network and so on. The technical purpose of at least one embodiment of the present invention is realized with the cooperation of the master machine and the slave machine. In a first aspect the present invention provides a master machine in a master-slave mode direct current carrier communication system which is comprised of a master machine, at least one slave machine, and signal bus used to connect the slave machine with the master machine, and the slave machine is connected in parallel between the signal bus extending from the master machine, wherein the master machine includes a master clock circuit, a master power supply system, a master communication interface, and a master control module; (as shown in FIG.2) the master clock circuit, the master power supply system, the master communication interface, and the master control module are all grounded to the ground one respectively; the operating voltage output terminal of the master power supply system is connected with the master communication interface, the master clock circuit, and the master control module; the other end of the master power supply system is the communication voltage output terminal leading to the communication voltage input terminal of the master communication interface; the master communication interface further includes two ends leading to the exterior of the master machine respectively, forming the signal bus; other ends of the master communication interface connect to the master control module; and the other end of the master clock circuit is connected with the master control module. The advantages of the solution lie in: firstly, the master power supply system supplies operating power for every module inside the master machine via the operating voltage output terminal of the master power supply system, and supplies charging power to the slave machine via the communication voltage output terminal of the master power supply system, which makes the charging power for the slave machine and the operating power for the master machine itself be supplied independently, therefore the possible effect of noise generated from the operation of the master machine upon the communication between the master machine and the slave machine can be avoided. Secondly, the master machine supplies direct current to the slave machine, which avoids the complicated conversion from alternating current to direct current when 3 alternating current is used to supply power, therefore, a simple linear power supply system can be used in the slave machine, which improves the reliability and the integratability of the slave machine. FIG. 18 shows the other solution of the master machine according to at least one embodiment of the present invention which is further improved based on the solution shown in FIG.2. The communication voltage output terminal of the master power supply system is subdivided into a transmitting voltage output terminal and a receiving voltage output terminal; the communication voltage input terminal of the master communication interface is subdivided into a transmitting voltage input terminal and a receiving voltage input terminal. The transmitting voltage output terminal of the master power supply system is connected to the transmitting voltage input terminal of the master communication interface; and the receiving voltage output terminal of the master power supply system is connected to the receiving voltage input terminal of the master communication interface. With the technical solution in which the communication voltage is further divided into a transmitting voltage and a receiving voltage, the Signal-to-Noise ratio of the data receiving of the master machine and the communication accuracy of the system can be improved. In the master machine shown in FIG.2, the master communication interface can be a master communication interface circuit. A first terminal of the master communication interface circuit is connected to the communication voltage output terminal of the master power supply system, forming the communication voltage input terminal of the master communication interface, shown in FIG.3. In the master machine shown in FIG. 18, the master communication interface can be comprised of the master communication interface circuit and a first electronic switch, as shown in FIG.19. Two input terminals of the first electronic switch lead to the exterior of the master communication interface, forming the transmitting voltage input terminal and the receiving voltage input terminal respectively; the output terminal of the first electronic switch is connected to the first terminal of the master communication interface circuit; the control terminal of the first electronic switch is connected to the master control module. The master communication interface circuit still includes another end which is connected to the operating voltage output terminal of the master power supply system, one end of the master communication interface circuit is grounded to the ground one, two ends of the master communication interface circuit lead to the exterior of the master communication interface respectively to form the signal bus, and the other end of the master communication interface circuit is connected to the master control module. The first electronic switch mentioned above realizes the switch between the transmitting voltage and the receiving voltage 4 under the control of the master control module. When the master machine transmits data to the slave machine, the master control module sends the control signal expressing the transmitting voltage outputting to the control terminal of the first electronic switch, rendering the branch circuit that the first electronic switch is connected to the transmitting voltage output terminal conducted, that is, the branch circuit that the first terminal of the master communication interface circuit is connected to the transmitting voltage output terminal of the master power supply system is conducted, thus the voltage on the signal bus will be the transmitting voltage, and vice versa. Therefore the separation of the transmitting voltage and the receiving voltage can be realized, setting a technical foundation for the improvement of the communication veracity. The master communication interface circuit shown in FIG.3 and FIG.19 can be a single-polarity communication interface circuit or a dual-polarity communication interface circuit. The single-polarity communication interface circuit includes a single-polarity data modulation module and a single-polarity data demodulation module, the detailed connection is described as the following three technical solutions: 1. As shown in FIG.4, both the single-polarity data modulation module and the single-polarity data demodulation module are connected to the operating voltage output terminal of the master power supply system; they are both grounded to the ground one; and each of them includes another end which connects to the master control module respectively. The modulation signal input terminal of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface circuit, forming the first terminal of the master communication interface circuit; the modulation signal output terminal of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface circuit via the single-polarity data demodulation module, forming one part of the signal bus; and the ground leads to the exterior of the single-polarity communication interface circuit, forming the other part of the signal bus. 2. As shown in FIG.5, the single-polarity data modulation module and the single-polarity data demodulation module are both connected to the operating voltage output terminal of the master power supply system; they are both grounded to the ground one; and each of them includes another end connecting to the master control module respectively. The modulation signal input terminal of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface circuit via the single-polarity data demodulation module, forming the first terminal; the ground and the modulation signal output terminal of the single-polarity data modulation module respectively lead 5 to the exterior of the single-polarity communication interface circuit, forming the signal bus. 3. As shown in FIG.6, the single-polarity data modulation module and the single-polarity data demodulation module are both connected to the operating voltage output terminal of the master power supply system; they are both grounded to the ground one; and each of them includes another end connecting to the master control module respectively. The modulation signal input terminal of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface circuit, forming the first terminal; the modulation signal output terminal of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface circuit, forming one part of the signal bus; and the other end of the single-polarity data demodulation module leads to the exterior of the single-polarity communication interface circuit, forming the other part of the signal bus. In the single-polarity communication interface circuits shown in FIG.4, FIG.5 and FIG.6, the simplex and bidirectional data exchange between the master machine and the slave machine via the DC powering bus is realized simply. In the three solutions mentioned above, three parts, which are respectively the single-polarity data modulation module, the single-polarity data demodulation module, and the master machine's output load which is constructed of the parallel network of the slave machines, are connected in series between the communication voltage output terminal of the master power supply system and the ground, and different connection sequences of the three parts have composed the three different solutions mentioned above. The single-polarity data modulation module is used to load the data output by the master machine upon the signal bus which is connected to the slave machine in the form of voltage changes, and the single-polarity data demodulation module is used to extract the data information on the signal bus loaded by the slave machine in the form of current changes. In the technical solutions of the single-polarity communication interface circuit shown in FIG.4, FIG.5 or FIG.6, the single-polarity data modulation module can include a first driving module and a second electronic switch, as shown in FIG.7, the detailed connection are as follows: one end of the first driving module is connected to the operating voltage output terminal of the master power supply system, one end of the first driving module and one input terminal of the second electronic switch are both grounded to the ground one; the signal input terminal of the first driving module is connected with the master control module; the signal output terminal of the first driving module is connected with the control terminal of the second electronic switch; and the other end of the first driving module and the other input terminal of the second electronic switch jointly lead to the exterior of the single-polarity data modulation 6 module, forming the modulation signal input terminal of the single-polarity data modulation module; and the output terminal of the second electronic switch leads to the exterior of the single-polarity data modulation module, forming the modulation signal output terminal of the single-polarity data modulation module. The advantage of the single-polarity data modulation module mentioned above lies in: during the process that the master machine supplies charging power to the slave machine, the data sent to the slave machine by the master machine is expressed in the form of the state of power-on or power-off of the charging power, thus realizing the simultaneousness of charging power supply and data transmission with such a simple and practical technical solution. The master communication interface circuit shown in FIG.3 and FIG.19 can be a dual-polarity communication interface circuit which includes a dual-polarity data modulation module and a dual-polarity data demodulation module. The detailed connection can be described as the following three technical solutions: 1. As shown in FIG.8, the dual-polarity data modulation module and the dual-polarity data demodulation module are both connected to the operating voltage output terminal of the master power supply system and they are both grounded to the ground one; and both of them also have one end connecting to the master control module respectively. The modulation signal input terminal of the dual-polarity data modulation module leads to the exterior of the dual-polarity communication interface circuit, forming the first terminal; one of the two modulation signal output terminals of the dual-polarity data modulation module leads to the exterior of the dual-polarity communication interface circuit via the dual-polarity data demodulation module, forming one part of the signal bus, and the other one directly leads to the exterior of the dual-polarity communication interface circuit, forming the other part of the signal bus. 2. As shown in FIG.9, the dual-polarity data modulation module and the dual-polarity data demodulation module are both connected to the operating voltage output terminal of the master power supply system, and they are both grounded to the ground one; and both of them also have one end connecting to the master control module respectively. The modulation signal input terminal of the dual-polarity data modulation module leads to the exterior of the dual-polarity communication interface circuit via the dual-polarity data demodulation module, forming the first terminal; and the two modulation signal output terminals of the dual-polarity data modulation module lead to the exterior of the dual-polarity communication interface circuit respectively, forming the signal bus. 3. As show in FIG.11, the dual-polarity data modulation module 7 and the dual-polarity data demodulation module are both connected to the operating voltage output terminal of the master power supply system; they are both grounded to the ground one, and each of them includes one end connecting to the master control module respectively. The modulation signal input terminal of the dual-polarity data modulation module leads to the exterior of the dual-polarity communication interface circuit, forming the first terminal; the two modulation signal output terminals of the dual-polarity data modulation module respectively lead to the exterior of the dual-polarity communication interface circuit, forming the signal bus; and the other end of the dual-polarity data modulation module is connected to the dual-polarity data demodulation module. The dual-polarity communication interface circuit shown in FIG.8, FIG.9 and FIG. 11 is further improved based on the single-polarity communication interface circuit shown in FIG.4, FIG.5 and FIG.6. And with the dual-polarity communication interface circuit, it is realized that during the process that the master machine supplies charging power to the slave machine, the master machine transmits data to the slave machine in the form of the state of positive communication voltage and negative communication voltage relative to the ground. The advantage of such solution lies in: when switching between different transmitting data, for example, switching from the transmitting data 0 to the transmitting data 1, because the polarity of the output voltage of the master machine is opposite, a discharge path in the reverse direction for the residual energy stored in the equivalent inductance or the equivalent capacitor of the signal bus is provided, therefore the data transmitting speed of such dual-polarity communication interface circuit is more rapid, the signal amplitude range is larger, and the ability of anti-jamming is higher. In the dual-polarity communication interface circuit shown in FIG.8 and FIG.9, the dual-polarity data modulation module includes a third driving module, a fourth driving module, a sixth electronic switch, a seventh electronic switch, and a first inverter, as shown in FIG.10. The detailed connection are as follows: the two driving modules and the first inverter are all connected to the operating voltage output terminal of the master power supply system jointly, and they are also grounded to the ground one; the signal input terminal of the first inverter and the signal input terminal of the fourth driving module are jointly connected to the master control module; the signal output terminal of the first inverter is connected to the signal input terminal of the third driving module; the signal output terminal of the third driving module is connected to the control terminal of the sixth electronic switch; the signal output terminal of the fourth driving module is connected to the control terminal of the seventh electronic switch. One input terminal of the sixth electronic switch, one input terminal of the seventh electronic switch, the other end 8 of the third driving module, and the other end of the fourth driving module connect together, and lead to the exterior of the dual-polarity data modulation module jointly, forming the modulation signal input terminal of the dual-polarity data modulation module; the other input terminal of the sixth electronic switch and the other input terminal of the seventh electronic switch are both grounded to the ground one; and the output terminals of the two electronic switches respectively lead to the exterior of the dual-polarity data modulation module, forming the two modulation signal output terminals of the dual-polarity data modulation module. In the dual-polarity communication interface circuit shown in FIG.11, the dual-polarity data modulation module includes a fifth driving module, a sixth driving module, an eighth electronic switch, a ninth electronic switch, a second inverter, as shown in FIG.12, the detailed connection are as follows: the two driving modules and the second inverter are jointly connected to the operating voltage output terminal of the master power supply system, and they are also grounded to the ground one together; the signal input terminal of the second inverter and the signal input terminal of the sixth driving module are both connected to the master control module, the signal output terminal of the second inverter is connected to the signal input terminal of the fifth driving module; the signal output terminal of the fifth driving module is connected to the control terminal of the eighth electronic switch, the signal output terminal of the sixth driving module is connected to the control terminal of the ninth electronic switch. One input terminal of the eighth electronic switch, one input terminal of the ninth electronic switch, the other end of the fifth driving module, and the other end of the sixth driving module connect together, and they all lead to the exterior of the dual-polarity data modulation module, forming the modulation signal input terminal of the dual-polarity data modulation module; the other input terminal of the eighth electronic switch is connected with the other input terminal of the ninth electronic switch and is grounded to the ground one via the dual-polarity data demodulation module at the exterior of the dual-polarity data modulation module; and the output terminals of the two electronic switches respectively lead to the exterior of the dual-polarity data modulation module, forming the two modulation signal output terminals of the dual-polarity data modulation module. Except the solution of the master communication interface shown in FIG.19, the master communication interface which forms up the master machine show in FIG.18 has several other technical solutions as follows: 1. The master communication interface shown in FIG.18 is a single-polarity communication interface including a single-polarity data 9 modulation module, a single-polarity data demodulation module, and a third electronic switch, as shown in FIG.20, the detailed connection are as follows: the single-polarity data modulation module and the single-polarity data demodulation module are jointly connected to the operating voltage output terminal of the master power supply system, and they are jointly grounded to the ground one; and each of them further includes one end connecting to the master control module respectively. The modulation signal input terminal of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface and further connects to the transmitting voltage output terminal of the master power supply system, forming the transmitting voltage input terminal of the single-polarity communication interface; the modulation signal output terminal of the single-polarity data modulation module is connected to one input terminal of the third electronic switch; the other end of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface, forming one part of the signal bus. The single-polarity data demodulation module further includes one end which is connected to the receiving voltage output terminal of the master power supply system, forming the receiving voltage input terminal of the single-polarity communication interface; the other end of the single-polarity data demodulation module is connected to the other input terminal of the third electronic switch. The control terminal of the third electronic switch is connected with the master control module; and the output terminal of the third electronic switch leads to the exterior of the single-polarity communication interface, forming the other part of the signal bus. A simpler single-polarity communication interface is used in the technical solution shown in FIG.20 to realize the simplex bidirectional data exchange between the master machine and the slave machine on the direct current charging bus. Wherein the single-polarity data modulation module is directly connected to the transmitting voltage output terminal of the master power supply system, the single-polarity data demodulation module is directly connected to the receiving voltage output terminal of the master power supply system, while the third electronic switch is used to accomplish the switch of the voltage output to the signal bus under the control of the master control module. When the master machine transmits data to the slave machine, the master control module sends the control signal to the control terminal of the third electronic switch to express that the transmitting voltage should be output, which conducts the branch circuit in which the third electronic switch is connected to the single-polarity data modulation module, thus the voltage on the signal bus will be the transmitting voltage, and vice versa. What is more, the separation of the transmitting voltage and the receiving voltage has been realized in the present technical solution as well, which sets up the technical 10 foundation for the improvement of the communication accuracy. In the single-polarity communication interface shown in FIG.20, the single-polarity data modulation module includes a second driving module and a fourth electronic switch, as shown in FIG.21, the detailed connection are as follows: one end of the second driving module is connected to the operating voltage output terminal of the master power supply system; the signal input terminal of the second driving module is connected with the master control module; the signal output terminal of the second driving module is connected with the control terminal of the fourth electronic switch; one end of the second driving module and one input terminal of the fourth electronic switch jointly lead to the exterior of the single-polarity data modulation module, forming the modulation signal input terminal of the single-polarity data modulation module. The other end of the second driving module and the other input terminal of the fourth electronic switch are jointly grounded to the ground one, and lead to the exterior of the single-polarity data modulation module, forming one part of the signal bus. The output terminal of the fourth electronic switch leads to the exterior of the single-polarity data modulation module, forming the modulation signal output terminal of the single-polarity data modulation module. 2. The master communication interface shown in FIG.18 also can be a dual-polarity communication interface including a dual-polarity data modulation module, a dual-polarity data demodulation module and a fifth electronic switch, as shown in FIG.22. The detailed connection are as follows: the dual-polarity data modulation module and the dual-polarity data demodulation module are both connected to the operating voltage output terminal of the master power supply system; they are both grounded to the ground one; and each of them also has one end connecting to the master control module respectively. The modulation signal input terminal of the dual-polarity data modulation module leads to the exterior of the dual-polarity communication interface to connect to the transmitting voltage output terminal of the master power supply system, forming the transmitting voltage input terminal of the dual-polarity communication interface; one of the two modulation signal output terminals of the dual-polarity data modulation module is connected to one input terminal of the fifth electronic switch, and the other one leads to the exterior of the dual-polarity communication interface, forming one part of the signal bus; the dual-polarity data demodulation module also has one end connected to the receiving voltage output terminal of the master power supply system, forming the receiving voltage input terminal of the dual-polarity communication interface; the other end of the dual-polarity data demodulation module is connected to the other input terminal of the fifth

II

electronic switch. The control terminal of the fifth electronic switch is connected with the master control module; and the output terminal of the fifth electronic switch leads to the exterior of the dual-polarity communication interface, forming the other part of the signal bus. The above technical solution of the dual-polarity communication interface shown in FIG.22 has realized the function that the master machine transmits data to the slave machine in the form of providing the positive communication voltage or the negative communication voltage relating to the ground while supplying charging power to the slave machine at the same time. Wherein the dual-polarity data modulation module is directly connected to the transmitting voltage output terminal of the master power supply system, the dual-polarity data demodulation module is directly connected to the receiving voltage output terminal of the master power supply system, while the fifth electronic switch is used to accomplish the switch of voltage output to the signal bus under the control of the master control module. When the master machine transmits data to the slave machine, the master control module sends a control signal to the control terminal of the fifth electronic switch to express that the transmitting voltage should be output, which conducts the branch circuit in which the fifth electronic switch is connected to the dual-polarity data modulation module, thus the voltage on the signal bus will be the transmitting voltage, and vice versa. What is more, the separation of the transmitting voltage and the receiving voltage has been realized in the present technical solution as well, which sets up the technical foundation for the improvement of the communication accuracy. In the technical solution of the dual-polarity communication interface shown in FIG.22, the composition, the connection and the operating principle of the dual-polarity data modulation module are given in the technical solution of the dual-polarity data modulation module shown in FIG.10 as a reference. The communication voltage output terminal of the master power supply system according to at least one embodiment of the present invention can be further subdivided into a transmitting voltage output terminal and a receiving voltage output terminal, and it is preferred that the output voltage of the transmitting voltage output terminal is higher than the output voltage of the receiving voltage output terminal. The advantages lie in: when the master machine is in a state of non-communication and data transmitting, the master machine outputs higher transmitting voltage to the signal bus in order to supply power for charging the energy storage module inside the slave machine. While the master machine is to receive data sent by the slave machine, if the master machine still outputs higher transmitting voltage to the signal bus, the energy storage module in the salve machine will continue obtaining charging energy from the signal bus, which will result in current noise on the signal bus, thus the Signal-to-Noise ratio will decrease during the process that the master machine receives data. Contrarily, when the master machine receives data 12 from the slave machine, if the voltage output to the signal bus by the master machine is decreased to make the voltage on the signal bus lower than the voltage of the energy storage module at the internal of the slave machine, all the slave machines in the network will be powered by their own respective energy storage module to keep itself operating. So when the master machine receives data, the current noise generated from the process that the slave machines obtain charging energy from the signal bus can be avoided, therefore the Signal-to-Noise ratio during the process of data transmitting of the slave machine will be increased, and the reliability of data receiving of the master machine can be improved. In a second aspect the present invention provides a slave machine in a master-slave mode direct current carrier communication system which is comprised of a master machine, at least one slave machine, and signal bus used to connect the slave machine with the master machine, and the slave machine is connected in parallel between the signal bus extending from the master machine, wherein: the slave machine includes a slave communication interface, a rectifier bridge circuit, an energy storage module, a slave power supply system, a slave clock circuit, and a slave control module (as shown in FIG.13); the slave communication interface, the rectifier bridge circuit, the energy storage module, the slave power supply system, the slave clock circuit, and the slave control module are all grounded to the ground two; the power supply input terminal of the slave power supply system is connected with the energy storage module, the power supply output terminal of the slave power supply system is connected with the slave control module, the slave clock circuit and the slave communication interface respectively; the slave communication interface and the rectifier bridge circuit each include two ends which lead to the exterior of the slave machine and connect to the signal bus respectively; the other end of the slave communication interface connects to the slave control module; the other end of the rectifier bridge circuit is connected to the energy storage module; and the other end of the slave clock circuit is connected to the slave control module. The advantages of the technical solution of the slave machine mentioned above lie in: Firstly, the use of the rectifier bridge circuit has realized the polarity transform of the input power supply of the slave machine, which eliminates the 13 connection polarity demands in the traditional network communication system and realizes the double-wire non-polarity connection between the master machine and the slave machine, therefore the connection process of the master-slave mode network system can be simplified and the possibility of the slave machine damage when powered resulting from connection mistakes in the network can be avoided. Secondly, the slave communication interface and the rectifier bridge circuit are connected in parallel between the two wires of the signal bus, which, on the one hand, avoids the effect on the data transmission speed between the master machine and the slave machine causing by the rectifier bridge circuit, on the other hand, makes the slave machine be able to receive single-polarity modulation data as well as dual-polarity modulation data. Thirdly, the energy storage module in the slave machine is used to store the energy supplied by the master machine, which makes the slave machine passive, so the power supplied to the entire communication system can be supplied to the master machine only, thus decreasing the complexity of power supply of the system, and improving the maintainability of the system. At the same time, the use of the energy storage module also furthest keeps the stability of the slave power supply system during the data transmission between the slave machine and the master machine, therefore the stability of the entire communication system can be improved. As one embodiment of the slave communication interface according to the present invention, the slave communication interface includes a slave data modulation module and a slave data demodulation module which is comprised of two slave data demodulation circuits, as shown in FIG.14. The two slave data demodulation circuits are respectively connected to the two wires of the signal bus, they are respectively connected to the slave control module, both of them are connected to the power supply output terminal of the slave power supply system, and they are grounded to the ground two jointly. One end of the slave data modulation module is connected with the slave control module, one end is grounded to the ground two, and the other two ends are respectively connected to the two wires of the signal bus. The advantage of the technical solution lies in: by using two slave data demodulation circuits which are exactly the same, working independently, and connected to the signal bus respectively, the slave machine can not only receive the single-polarity modulation data output by the master machine, but also the dual-polarity modulation data output by the master machine, which makes the slave machine well adoptable and applicable in different systems with different communication requirements. The slave data modulation module of at least one embodiment of the present invention can include a first resistor, a second resistor, a third resister, a first NMOS transistor, and a second NMOS transistor, as shown in FIG.15. The drain and the substrate of the first NMOS 14 transistor, the drain and the substrate of the second NMOS transistor, and one end of the first resistor are jointly grounded to the ground two; the grid of the first NMOS transistor, the grid of the second NMOS transistor, and the other end of the first resistor connect together, and connect to the slave control module together; the source of the first NMOS transistor is connected to one part of the signal bus via the second resistor, and the source of the second NMOS transistor is connected to the other part of the signal bus via the third resistor. The slave data modulation module mentioned above realizes the function of loading the data to be sent to the signal bus in the form of current consumption changes, the advantage of which lies in: because the source and the drain of the first NMOS transistor and the source and the drain of the second NMOS transistor are respectively connected to the ground and the signal bus, the effect on the consistency of current consumption changes caused by individual differences of voltage drop of the rectifier bridge circuit will be reduced, making the current consumption changes transmitted by the slave machine to the master machine depend only on the voltage of the signal bus. The slave data demodulation circuit of at least one embodiment of the present invention includes a third inverter and a fourth resistor, as shown in FIG. 16. One end of the third inverter is connected to the power supply output terminal of the slave power supply system; the signal input terminal of the third inverter is connected to one part of the signal bus, and this terminal is also grounded to the ground two via the fourth resistor; the signal output terminal of the third inverter is connected to the slave control module; and the other end of the third inverter is grounded to the ground two directly. The structure of the slave data demodulation circuit is quite simple and easy to integrate. With the function of pull-down of the fourth resistor, the output of the slave data demodulation circuit is ensured to be always in a definite state no matter what kind of state the signal bus is in, such as the state of positive communication voltage, negative communication voltage, or zero voltage, thus improving the reliability of the communication system; and, at the same time, with the function of pull-down of the fourth resistor, the consumption of the energy stored in the energy storage module in the slave machine when the input of the third inverter is in an indefinite state is reduced, thus increasing the efficient utilization rate of the energy stored in the slave machine. In addition, when the data on the signal bus change, the fourth resistor also provides a discharging path for the residual charge on the bus, thus improving the communication speed. The slave data demodulation circuit in the present invention can include a fourth inverter and a third NMOS transistor, as shown in FIG.17. One end of the fourth inverter is connected with the power supply output terminal of the slave power supply system, one end of the 15 fourth inverter is grounded to the ground two; the source and the substrate of the third NMOS transistor is grounded to the ground two; its drain and the signal input terminal of the fourth inverter connect together, and are connected to one part of the signal bus; and the grid of the third NMOS transistor and the signal output terminal of the fourth inverter connect together, and are connected to the slave control module jointly. The pull-down fourth resistor is replaced by the third NMOS transistor which is connected in the way of negative feedback in the slave data demodulation circuit mentioned above, and the advantage is to avoid energy consumption caused by the fourth resistor and to improve the utilization efficiency of the energy provided by the master machine. In addition, the characteristic of dynamic resistance of an NMOS transistor is adopted in this solution, and when the input of the bus is at low level, the output of the fourth inverter will be at high level, and the third NMOS transistor will be in a state of conduction. Therefore, when the communication data sent on the bus makes the voltage of the bus switch from high level to low level, the third NMOS transistor can accelerate the discharging process of the residual charge on the bus, thus improving the communication speed of the communication system. The Schmitt inverter is a better choice of the third inverter and the fourth inverter in the two technical solutions of the slave data demodulation circuit mentioned above. The advantage lies in: whether state switching of the signal input to the inverter is slow or not, that is, whether the transition time of the level switching takes long or not, the output edge of the inverter will be relatively steep and the transition time of level switching of its output will be incredibly short, which reduces the time for state transition that the follow-up processing circuit of the slave data demodulation circuit takes and reduces the power consumption of the slave machine. In addition, the Schmitt inverter has good anti-noise performance, which can improve the stability of the function of data receiving of the slave machine. Brief Description of the Drawings FIG. 1 is a network connection diagram of the master-slave mode direct current carrier communication system according to the invention; FIG.2 is a composition diagram of the master machine which receives and transmits data under the same voltage according to the invention; FIG.3 shows an embodiment of the master communication interface which includes a master communication interface circuit according to the invention; FIG.4 shows the first embodiment of the single-polarity communication interface circuit according to the invention; FIG.5 shows the second embodiment of the single-polarity communication interface circuit according to the invention; 16 FIG.6 shows the third embodiment of the single-polarity communication interface circuit according to the invention; FIG.7 shows the first embodiment of the single-polarity data modulation module according to the invention; FIG.8 shows the first embodiment of the dual-polarity communication interface circuit according to the invention; FIG.9 shows the second embodiment of the dual-polarity communication interface circuit according to the invention; FIG.1O shows the first embodiment of the dual-polarity data modulation module according to the invention; FIG.11 shows the third embodiment of the dual-polarity communication interface circuit according to the invention; FIG.12 shows the second embodiment of the dual-polarity data modulation module according to the invention; FIG. 13 is a composition diagram of the slave machine according to the invention; FIG.14 is a composition diagram of the slave communication interface according to the invention; FIG.15 is a composition diagram of the slave data modulation module according to the invention; FIG.16 shows the first embodiment of the slave data demodulation circuit according to the invention; FIG.17 shows the second embodiment of the slave data demodulation circuit according to the invention; FIG.18 is a composition diagram of the master machine using different voltages to receive and transmit data according to the invention; FIG.19 shows an embodiment of the master communication interface which includes an electronic switch and a master communication interface circuit according to the invention; FIG.20 shows an embodiment of the master communication interface which is a single-polarity communication interface according to the invention; FIG.21 shows the second embodiment of the single-polarity data modulation module according to the invention; FIG.22 shows an embodiment of the master communication interface which is a dual-polarity communication interface according to the invention; 17 FIG. 23-1 shows the waveform of the single-polarity data sent to the slave machine by the single-polarity data modulation module in the master machine which uses the same voltage to receive and transmit data according to the invention; FIG.23-2 shows one waveform of the single-polarity data which are received and demodulated by the slave machine according to the invention; FIG.23-2 shows the other waveform of the single-polarity data which are received and demodulated by the slave machine according to the invention; FIG.24-1 shows the waveform of the dual-polarity data sent to the slave machine by the dual-polarity data modulation module in the master machine which uses the same voltage to receive and transmit data according to the invention; FIG.24-2 shows one waveform of the dual-polarity data which are received and demodulated by the slave machine according to the invention; FIG.24-3 shows the other waveform of the dual-polarity data which are received and demodulated by the slave machine according to the invention; FIG.25-1 shows the voltage waveform when the slave machine modulates and transmits data according to the invention; FIG.25-2 shows the current waveform when the slave machine modulates and transmits data according to the invention; FIG.26 shows the waveform when the single-polarity data modulation module in the master machine which uses different voltages to receive and transmit data transmits a single-polarity global instruction to the slave machine according to the invention; FIG.27 shows the waveform when the dual-polarity data modulation module in the master machine which uses different voltages to receive and transmit data transmits a dual-polarity single instruction to the slave machine according to the invention. Detailed Description of Embodiments The following further describes the embodiments of the present invention in more details with reference to accompanying drawings. As FIG.1 shows, the master-slave mode direct current carrier communication system according to the present invention is comprised of a master machine 100, one or more slave machines 200, and the signal bus 300 used to connect the master machine 100 and the slave machines 200. One or more slave machines 200 are respectively and independently 18 connected in parallel between the signal bus 300 extending from the master machine 100. With the cooperation of the master machine 100 and the slave machine 200, the simplex and bidirectional data exchange between the master machine and the slave machine during the process that the master machine supplies power for the slave machine is realized, and double-wire non-polarity connection between the master machine and the slave machine is also realized, therefore the design and connection of the master machine 100 and the slave machine 200 are simplified as well. As one aspect of the present invention, the master machine 100 can include a master clock circuit 140, a master power supply system 130, a master communication interface 150, and a master control module 120, as shown in FIG.2. The detailed connection can be described as follows: (1) The operating voltage output terminal 31 of the master power supply system 130 is connected with the master clock circuit 140, the master control module 120, and the master communication interface 150, supplying operating power to them. The communication voltage output terminal 32 of the master power supply system 130 is connected to the communication voltage input terminal 51 of the master communication interface 150, outputting the energy needed by the slave machine 200 to operate to the signal bus 300 via the master communication interface 150. The other end of the master power supply system 130 is grounded to the ground 40. (2) One end of the master clock circuit 140 is connected with the master control module 120, supplying the clock signal to the master control module 120 to operate; one end is connected with the operating voltage output terminal 31 of the master power supply system 130, receiving the operating power supplied by the master power supply system 130; and the other end is grounded to the ground 40. (3) The master communication interface 150 is connected with the master control module 120. The purpose of this connection lies in: on the one hand, the master communication interface 150 receives the control signal sent by the master control module 120, and further supplies operating power needed by the slave machine 200 or sends the data to be sent to the slave machine 200 to the slave machine via the signal bus 300; on the other hand, the master communication interface 150 extracts the data information on the signal bus 300 sent by the slave machine 200 and transmits the data information to the master control module 120 for further processing. The other end of the master communication interface 150 is connected to the operating voltage output terminal 31 of the master power supply system 130 to receive the operating voltage supplied by the master power supply system 130. The communication voltage input terminal 51 of the master communication interface 150 is connected to the communication voltage output terminal 32 of the 19 master power supply system 130, receiving the communication voltage supplied by the master power supply system 130. The master communication interface 150 also has one end connecting to the ground 40, and two ends leading to the exterior of the master machine, forming the signal bus 300 used to connect one or more slave machines 200. The master machine 100 supplies operating power for the slave machine 200 and exchanges data with the slave machine 200 via the signal bus 300. (4) The other end of the master control module 120 is grounded to the ground 40. The advantages of the design of the master machine shown in FIG.2 lie in: Firstly, the master power supply system 130 supplies operating power for every module at the internal of the master machine via its operating voltage output terminal 31, and supplies charging power for the slave machine 200 via its communication voltage output terminal 32, which makes the charging power for the slave machine 200 and the operating power for the master machine 100 itself be supplied independently, thus avoiding the possible effect on the communication between the master machine and the slave machine caused by the noise generated from the operation of the master machine. Secondly, the master machine 100 supplies direct current for the slave machine 200, avoiding the complicated transform which is from alternating current to direct current when alternating current is used to supply power, therefore a simple linear power supply system can be used in the slave machine 200, which improves the reliability and the integratability of the slave machine. As one embodiment of the master communication interface according to the present invention, the master communication interface 150 is a master communication interface circuit 153, as shown in FIG.3. The terminal 20 of the master communication interface circuit 153 is connected to the communication voltage output terminal 32 of the master power supply system 130, forming the communication voltage input terminal 51 of the master communication interface 150, receiving the communication voltage supplied by the master power supply system 130. As one embodiment of the master communication interface circuit 153 shown in FIG.3, the master communication interface circuit can be a single-polarity communication interface circuit which includes a single-polarity data modulation module 1011 and a single-polarity data demodulation module 102. The detailed connection can be carried out as the following three embodiments: 1. As shown in FIG.4, both the single-polarity data modulation 20 module 1011 and the single-polarity data demodulation module 102 are connected to the operating voltage output terminal 31 of the master power supply system 130, being powered by the master power supply system 130. They are both grounded to the ground 40; and each of the single-polarity data modulation module 1011 and the single-polarity data demodulation module 102 includes another end which connects to the master control module 120 respectively and exchanges data with the master control module 120. The modulation signal input terminal 12 of the single-polarity data modulation module 1011 leads to the exterior of the single-polarity communication interface circuit 1531, forming the terminal 20 of the single-polarity communication interface circuit 153 1. The modulation signal output terminal 11 of the single-polarity data modulation module 1011 leads to the exterior of the single-polarity communication interface circuit 1531 via the single-polarity data demodulation module 102, forming one part of the signal bus; and the ground leads to the exterior of the single-polarity communication interface circuit 153 1, forming the other part of the signal bus 300. 2. As shown in FIG.5, the single-polarity data modulation module 1011 and the single-polarity data demodulation module 102 are both connected to the operating voltage output terminal 31 of the master power supply system 130, being powered by the master power supply system 130. They are both grounded to the ground 40; and each of the single-polarity data modulation module 1011 and the single-polarity data demodulation module 102 includes another end connecting to the master control module 120 respectively and exchanging data with the master control module 120. The modulation signal input terminal 12 of the single-polarity data modulation module 1011 leads to the exterior of the single-polarity communication interface circuit 1532 via the single-polarity data demodulation module 102, forming the terminal 20 of the single-polarity communication interface circuit 1532; The ground and the modulation signal output terminal 11 of the single-polarity data modulation module 1011 respectively lead to the exterior of the single-polarity communication interface circuit 1532, forming the signal bus 300. 3. As shown in FIG.6, the single-polarity data modulation module 1011 and the single-polarity data demodulation module 102 are both connected to the operating voltage output terminal 31 of the master power supply system 130, being powered by the master power supply system 130. They are both grounded to the ground 40; and each of the single-polarity data modulation module 1011 and the single-polarity data demodulation module 102 includes another end connecting to the master control module 120 and exchanging data with the master control module 120 respectively. The modulation signal input terminal 12 of the 21 single-polarity data modulation module 1011 leads to the exterior of the single-polarity communication interface circuit 1533, forming the terminal 20 of the single-polarity communication interface circuit 1533. The modulation signal output terminal 11 of the single-polarity data modulation module 1011 leads to the exterior of the single-polarity communication interface circuit 1533, forming one part of the signal bus 300. The other end of the single-polarity data demodulation module 102 leads to the exterior of the single-polarity communication interface circuit 1533, forming the other part of the signal bus 300. The single-polarity communication interface circuits shown in FIG.4, FIG.5 and FIG.6 have realized the simplex bidirectional data exchange between the master machine and the slave machine via the direct current charging bus (which is the signal bus 300) with the simpler embodiments. In the three embodiments mentioned above, three parts, which are respectively the single-polarity data modulation module 1011, the single-polarity data demodulation module 102, and the output load of the master machine 100 which is constructed of the parallel network of the slave machines 200, are connected in series between the communication voltage output terminal 32 of the master power supply system 130 and the ground, as shown in FIG.1, and the different connection sequences of the three parts have composed the three different embodiments mentioned above. When the single-polarity data modulation module 1011 is not sending data to the slave machine 200, it is used to supply operating power in the mode of direct current for the slave machine 200 via the signal bus 300; when sending data to the slave machine 200, the single-polarity data modulation module 1011 is used to load the data output by the master machine 100 upon the signal bus 300 connected to the slave machine 200 in the form of voltage changes. The single-polarity data demodulation module 102 is used to extract the current change information on the signal bus 300 loaded upon by the slave machine 200 in the form of current changes of the output loading of the master machine. In the embodiment of the single-polarity communication interface circuit shown in FIG.4, FIG.5 or FIG.6, the single-polarity data modulation module 1011 can include an electronic switch 122 and a driving module IIl as shown in FIG.7. One end of the driving module 111 is connected to the operating voltage output terminal 31 of the master power supply system 130 to receive the operating voltage output by the master power supply system 130 and supply low driving voltage to the driving module 111. One end of the driving module 111 and one input terminal of the second electronic switch 122 are both grounded to the ground 40. The signal input terminal of the driving module 111 is connected with the master control module 120 to receive the low level control signal output by the master control module 120. The signal output terminal of the driving module 111 is connected with the control 22 terminal of the electronic switch 122 to transform the received low level control signal to the high level control signal to control which branch of the electronic switch 122 to conduct. The other end of the driving module 111 and the other input terminal of the electronic switch 122 jointly lead to the exterior of the single-polarity data modulation module 1011, forming the modulation signal input terminal 12. The modulation signal input terminal 12 is used to receive the higher communication voltage directly or indirectly supplied by the master power supply system 130 at the exterior of the single-polarity data modulation module 1011, and to supply high driving voltage to the driving module 111. The output terminal of the electronic switch 122 leads to the exterior of the single-polarity data modulation module 1011, forming the modulation signal output terminal 11. As shown in FIG.7, when the master machine does not transmit data to the slave machine, the branch circuit in which the electronic switch 122 connects to the modulation signal input terminal 12 conducts, and the modulation signal output terminal 11 will output direct current power to the slave machine 200; when the master machine transmits data to the slave machine, the electronic switch 122 will switch between the branch circuit in which the electronic switch 122 connects to the modulation signal input terminal 12 and the branch circuit in which the electronic switch 122 connects to the ground, and the modulation signal output terminal 11 will output modulated signal to the salve machine 200, as shown in FIG.23-las a reference. The connection between the single-polarity data modulation module 1011 and the single-polarity data demodulation module at the exterior of it can embody any connection mode of the single-polarity data demodulation module 1021, 1022 or 1023, that is: the modulation signal input terminal 12 of the single-polarity data modulation module 1011 is connected to the master power supply system 130 via the single-polarity data demodulation module 1021, as the embodiment shown in FIG.5; or, the modulation signal output terminal 11 of the single-polarity data modulation module 1011 forms one part of the two wires of the signal bus 300 via the single-polarity data demodulation module 1022, as the embodiment shown in FIG. 4; or, one end of the single-polarity data demodulation module 1023 is grounded to the ground 40 from the exterior of the single-polarity data modulation module 1011, and the other end leads to the exterior of the single-polarity communication interface circuit to form one part of the two wires of the signal bus 300, as the embodiment shown in FIG.6. The other connections of the single-polarity data demodulation module in FIG. 7 are nearly the same as the corresponding connections shown in FIG.4, FIG.5 and FIG.6. 23 In the embodiments of the single-polarity communication interface circuit, the master machine 100 sends the data "1" or "0" to the slave machine 200 in the form of the state of power-on or power-off of the charging power during the process that the master machine 100 supplies charging power to the slave machine 200. The operating principle can be described as follows: 1. When the master machine is not transmitting data to the slave machines 200 or is not receiving data from the slave machines 200, the control signal at low level output by the master control module 120 to the driving module I11 is transformed to the control signal at high level under the control of the driving module 111, and the control signal at high level is output to the control terminal of the electronic switch 122, which conducts the branch circuit in which the electronic switch 122 is connected to the modulation signal input terminal 12, as shown in FIG.7, and then the master machine 100 will output direct current power to the slave machines 200 via the signal bus 300. 2. When transmitting the data "1" to all the slave machines 200, the master control module 120 sends a control signal at low level expressing the data "1" to the driving module 111; via the driving module 111, the control signal at low level said above is transformed to a control signal at high level expressing the data "1" which is further transmitted to the control terminal of the electronic switch 122; further, the branch circuit in which the electronic switch 122 connects to the modulation signal input terminal 12 conducts, as shown in FIG.7. And then the modulation signal output terminal 11 of the single-polarity data modulation module 1011 will output the communication voltage. 3. When transmitting the data "0" to all the slave machines 200, the master control module 120 sends a control signal at low level expressing the data "0" to the driving module 111; via the driving module 111, the control signal at low level said above is transformed to a control signal at high level expressing the data "0" which is further transmitted to the control terminal of the electronic switch 122; further, the branch circuit in which the electronic switch 122 connects to the ground conducts. And then the modulation signal output terminal 11 of the single-polarity data modulation module 1011 will output the zero voltage. According to the operating principle of the single-polarity communication interface circuit, the modulation signals output by the single-polarity data modulation module 1011 can be represented in the waveform as shown in FIG.23-1. In FIG.23-1, VIN represents the value of the communication voltage output by the master machine 100 to the slave machines 200. The voltage on the signal bus 300 is changing between the communication voltage VIN and the zero. A dual-polarity communication interface circuit including a 24 dual-polarity data modulation module and a dual-polarity data demodulation module can also be chosen as an embodiment of the master communication interface circuit 153 shown in FIG.3. The detailed connection can be described as the following three embodiments: 1. As shown in FIG.8, the dual-polarity data modulation module 1051 and the dual-polarity data demodulation module 106 are both connected to the operating voltage output terminal 31 of the master power supply system 130, being powered by the master power supply system 130. The dual-polarity data modulation module 1051 and the dual-polarity data demodulation module 106 are both grounded to the ground 40. and each of the dual-polarity data modulation module 1051 and the dual-polarity data demodulation module 106 also have one end respectively connecting to the master control module 120 and exchanging data with the master control module 120. The modulation signal input terminal 19 of the dual-polarity data modulation module 1051 leads to the exterior of the dual-polarity communication interface circuit 1534, forming the terminal 20. One modulation signal output terminal 16 of the dual-polarity data modulation module 1051 leads to the exterior of the dual-polarity communication interface circuit 1534 via the dual-polarity data demodulation module 106, forming one part of the signal bus 300, and the other modulation signal output terminal 17 directly leads to the exterior of the dual-polarity communication interface circuit 1534, forming the other part of the signal bus 300. In the dual-polarity communication interface circuit 1534 of this present embodiment, the dual-polarity data demodulation module 106 is used to extract the current change information on the signal bus 300 resulting from the outputting load of the master machine which is caused by all the slave machines 200. 2. As shown in FIG.9, the dual-polarity data modulation module 1051 and the dual-polarity data demodulation module 106 are both connected to the operating voltage output terminal 31 of the master power supply system 130, being powered by the master power supply system 130. The dual-polarity data modulation module 1051 and the dual-polarity data demodulation module 106 are both grounded to the ground 40. And each of the dual-polarity data modulation module 1051 and the dual-polarity data demodulation module 106 also have one end connecting to the master control module 120 and exchanging data with the master control module 120 respectively. The modulation signal input terminal 19 of the dual-polarity data modulation module 1051 leads to the exterior of the dual-polarity communication interface circuit 1535 via the dual-polarity data demodulation module 106, forming the terminal 20. The two modulation signal output terminals 16 and 17 of the dual-polarity data modulation module 1051 lead to the exterior of the 25 dual-polarity communication interface circuit 1535 respectively, forming the signal bus 300. In the dual-polarity communication interface circuit 1535 of this present embodiment, the dual-polarity data demodulation module 106 is used to extract the current change information on the signal bus 300 resulting from the outputting load of the master machine caused by all the slave machines 200, and the information is expressed by the output of the master power supply system 130 to the dual-polarity data demodulation module 106. 3. As show in FIG.11, the dual-polarity data modulation module 1052 and the dual-polarity data demodulation module 106 are both connected to the operating voltage output terminal 31 of the master power supply system 130, being powered by the master power supply system 130. They are both grounded to the ground 40, and each of them include one end connecting to the master control module 120 and exchanging data with the master control module 120 respectively. The modulation signal input terminal 19 of the dual-polarity data modulation module 1052 leads to the exterior of the dual-polarity communication interface circuit 1536, forming the terminal 20. The two modulation signal output terminals 16 and 17 of the dual-polarity data modulation module 1052 respectively lead to the exterior of the dual-polarity communication interface circuit 1536, forming the signal bus 300. And the other end of the dual-polarity data modulation module 1052 is connected to the dual-polarity data demodulation module 106. In the dual-polarity communication interface circuit 1536 of this present embodiment, the dual-polarity data demodulation module 106 is used to extract the current change information on the signal bus 300 resulting from the outputting load of the master machine caused by all the slave machines 200. The information is output to the reference ground 40 of the master power supply system 130 via the dual-polarity data modulation module 1052, and is expressed by the output of the master power supply system 130 to the dual-polarity data demodulation module 106. The dual-polarity communication interface circuit shown in FIG.8, FIG.9 and FIG.11 is further improved based on the embodiments of the single-polarity communication interface circuit shown in FIG.4, FIG.5 and FIG.6. And with the dual-polarity data modulation module, it is realized that during the process when the master machine supplies charging power to the slave machine, the master machine transmits data to the slave machine in the form of the state of positive communication voltage and negative communication voltage relative to the reference ground 40. The advantage of such embodiments lies in: when switching between different transmitting data, for example, switching from the transmitting data "0" to the transmitting data "1", because the polarity of the output voltage of the master machine is 26 opposite, a discharge path in the reverse direction for the residual energy stored in the equivalent inductance or the equivalent capacitor of the signal bus is provided, therefore the data transmitting speed of such dual-polarity communication interface circuit is more rapid, the signal amplitude range is larger, and the ability of anti-jamming is higher. In the dual-polarity communication interface circuit shown in FIG.8 or FIG.9, the dual-polarity data modulation module 1051 includes a driving module 113, a driving module 114, an electronic switch 126, an electronic switch 127, and an inverter 301, as shown in FIG.10. The two driving modules 113 and 114 and the inverter 301 are all connected to the operating voltage output terminal 31 of the master power supply system 130 jointly, and they are also grounded to the ground 40. The signal input terminal of the inverter 301 and the signal input terminal of the driving module 114 are jointly connected to the master control module 120; the signal output terminal of the inverter 301 is connected to the signal input terminal of the driving module 113. The signal output terminal of the driving module 113 is connected to the control terminal of the electronic switch 126; the signal output terminal of the driving module 114 is connected to the control terminal of the electronic switch 127. One input terminal of the electronic switch 126, one input terminal of the electronic switch 127, the other end of the driving module 113, and the other end of the driving module 114 connect together, and lead to the exterior of the dual-polarity data modulation module 1051 jointly, forming the modulation signal input terminal 19 of the dual-polarity data modulation module 1051. The other input terminal of the electronic switch 126 and the other input terminal of the electronic switch 127 are both grounded to the ground 40. And the output terminals of the two electronic switches 126 and 127 respectively lead to the exterior of the dual-polarity data modulation module 1051, forming the two modulation signal output terminals 16 and 17 of the dual-polarity data modulation module 1051. As shown in FIG.10, the connection between the dual-polarity data modulation module 1051 and the dual-polarity data demodulation module at the exterior of it can embody any connection mode of the dual-polarity data demodulation module 1061, 1062 or 1063, that is: the modulation signal input terminal 19 of the dual-polarity data modulation module 105 1 is connected to the master power supply system 130 via the dual-polarity data demodulation module 1061, as the embodiment shown in FIG.9; or, the modulation signal output terminal 16 or 17 of the dual-polarity data modulation module 1051 leads to the exterior of the dual-polarity communication interface circuit via the dual-polarity data demodulation module, forming one part of the two wires of the signal bus 300, as the embodiment shown in FIG.8. The other connections of 27 the dual-polarity data demodulation module in FIG.10 are nearly the same as the corresponding connections shown in FIG.8 and FIG.9. In the dual-polarity communication interface circuit 1536 shown in FIG.ll, the dual-polarity data modulation module 1052 includes a driving module 115, a driving module 116, an electronic switch 128, an electronic switch 129, and an inverter 302, as shown in FIG.12. The two driving modules 115 and 116 and the inverter 302 are jointly connected to the operating voltage output terminal 31 of the master power supply system 130, and they are also grounded to the ground 40 together. The signal input terminal of the inverter 302 and the signal input terminal of the driving module 116 are both connected to the master control module 120, the signal output terminal of the inverter 302 is connected to the signal input terminal of the driving module 115. The signal output terminal of the driving module 115 is connected to the control terminal of the electronic switch 128; the signal output terminal of the driving module 116 is connected to the control terminal of the electronic switch 129. One input terminal of the electronic switch 128, one input terminal of the electronic switch 129, the other end of the driving module 115, and the other end of the driving module 116 connect together, and they all lead to the exterior of the dual-polarity data modulation module 1052, forming the modulation signal input terminal 19 of the dual-polarity data modulation module 1052. The other input terminal of the electronic switch 128 is connected with the other input terminal of the electronic switch 129 and is grounded to the ground 40 via the dual-polarity data demodulation module 106 at the exterior of the dual-polarity data modulation module 1052. And the output terminals of the two electronic switches 128 and 129 respectively lead to the exterior of the dual-polarity data modulation module 1052, forming the two modulation signal output terminals 16 and 17 of the dual-polarity data modulation module 1052. In the embodiments of the dual-polarity communication interface circuit shown in FIG.8, FIG.9 and FIG.11, during the process when the master machine 100 supplies charging power to the slave machine 200, the master machine 100 transmits data "1" or data "0" to the slave machine 200 in the form of the state of positive communication voltage and negative communication voltage relative to the reference power ground 40. Take the embodiment shown in FIG.10 as an example, the operating principle of the dual-polarity data modulation module can be described as follows: 1. When the master machine does not transmit data to the slave machines 200 or receive data from the slave machines 200, the low level control signal which is output by the master control module 120 to the driving module 114 and simultaneously to the driving module 113 via the inverter 301 is transformed to the high level control signal under the 28 control of the driving module 113 and 114, and the high level control signal is respectively output to the control terminal of the electronic switch 127 and the control terminal of the electronic switch 126, which conducts the branch circuit in which the electronic switch 127 connects to the modulation signal input terminal 19 and the branch circuit in which the electronic switch 126 connects to the ground 40, as shown in FIG.10 as a reference. Then the master machine 100 outputs direct current power to the slave machines 200 via the signal bus 300. 2. When transmitting the data "1" to all the slave machines 200, the master control module 120 sends a low level control signal expressing the data "1" to the driving module 114 and the inverter 301 simultaneously. Via the driving module 114, the low level control signal is transformed to a high level control signal expressing the data "1" which is further transmitted to the control terminal of the electronic switch 127. At the same time, via the inverter 301, the low level control signal expressing the data "1" output by the master control module 120 is transformed to a low level control signal expressing the data "0" which is further output to the driving module 113; the driving module 113 transforms the low level control signal expressing the data "0" to a high level control signal expressing the data "0" which is then output to the control terminal of the electronic switch 126. Then the branch circuit in which the electronic switch 127 connects to the modulation signal input terminal 19 conducts, and the branch circuit in which the electronic switch 126 connects to the ground 40 conducts, as shown in FIG.10 as s reference. Then the modulation signal output terminal 17 of the dual-polarity data modulation module 1051 will output the communication voltage while the modulation signal output terminal 16 of the dual-polarity data modulation module 1051 will output zero voltage, that is, the positive communication voltage mentioned above will be output. 3. When transmitting the data "0" to all the slave machines 200, the master control module 120 sends a low level control signal expressing the data "0" to the driving module 114 and the inverter 301 simultaneously. Via the driving module 114, the low level control signal is transformed to a high level control signal expressing the data "0" which is further transmitted to the control terminal of the electronic switch 127. At the same time, via the inverter 301, the low level control signal expressing the data "0" output by the master control module 120 is transformed to a low level control signal expressing the data "1" which is then output to the driving module 113; the driving module 113 transforms the low level control signal expressing the data "1" to a high level control signal expressing the data "1" which is then output to the control terminal of the electronic switch 126. Then the branch circuit in 29 which the electronic switch 127 connects to the ground 40 conducts, and the branch circuit in which the electronic switch 126 connects to the modulation signal input terminal 19 conducts. Then the modulation signal output terminal 17 of the dual-polarity data modulation module 1051 will output the zero voltage while the modulation signal output terminal 16 will output the communication voltage, thus the master machine 100 will output a voltage signal with the opposite polarity to the signal when transmitting the data "1" to the signal bus 300, that is, the negative communication voltage mentioned above will be output. The operating principle of the dual-polarity communication interface circuit 1536 shown in FIG.12 is nearly the same as the operating principle described above. According to the operating principle of the dual-polarity communication interface circuit, the modulation signal output by the dual-polarity data modulation module can be represented in the waveform shown in FIG.24-1. In FIG.24-1, VIN represents the value of the communication voltage output by the master machine 100 to the slave machines 200. The voltage on the signal bus 300 is changing between the positive communication voltage VIN and the negative communication voltage VIN A circuit module, which includes two power supplies that are a low voltage power supply and a high voltage power supply respectively, and which can transform the input signal at low level to the output signal at high level, such as the 74LS4245 or the IR53HD420, can be used as the driving module shown in FIG.7, FIG.10 or FIG.12. The circuit component which can transform the current change information input to it to the voltage change information to output, such as a resistors or an inductance, can be used as the single-polarity data demodulation module and the dual-polarity data demodulation module mentioned above. The descriptions to the embodiments of the master machine have been given above, As the other aspect of the present invention, the slave machine 200 includes a slave communication interface 210, a rectifier bridge circuit 260, an energy storage module 240, a slave power supply system 230, a slave clock circuit 250, and a slave control module 220, as shown in FIG. 13. The detailed connection can be described as follows: (1) The slave communication interface 210 is connected with the slave control module 220. On the one hand, the slave communication interface 210 is used to transmit the extracted data which are loaded upon the signal bus 300 by the master machine 100 to the salve control module 220 for further processing; on the other hand, the slave communication interface 210 is used to load the data information that the slave control module 220 needs to transmit to the master machine 30 100 upon the signal bus 300. One end of the slave communication interface 210 is connected to the power supply output terminal 35 of the slave power supply system 230 to receive the operating voltage and the reset signal sent by the slave power supply system 230. The slave communication interface 210 also has one end being grounded to the ground 50 and two ends connecting to the signal bus 300 respectively to extract signals from the bus 300 or to load data upon the bus 300. (2) One end of the rectifier bridge circuit 260 is connected to the energy storage module 240, one end is connected to the ground 50, and the other two ends are connected to the signal bus 300. The rectifier bridge circuit 260 is used to adjust the polarity of the power supplied by the master machine 100 to the slave machine 200 via the signal bus 300, to realize the non-polarity connection between the master machine 100 and the slave machine 200; and the rectifier bridge circuit 260 is also used to store the energy in the energy storage module 240 to meet the needs of the salve machine 200 for operating. One end of the energy storage module 240 is connected to the rectifier bridge circuit 260, receiving the energy output by the rectifier bridge circuit 260. One end of the energy storage module 240 is connected with the power supply input terminal 36 of the slave power supply system 230; and the energy storage module 240 is used to supply power stored in the energy storage module 240 to the slave power supply system 230, and the slave power supply system 230 will transform the power to the operating voltage needed by the slave machine 200, when the external power supply is interrupted during the process of receiving data. The other end of the energy storage module 240 is grounded to the ground 50. (4) The power supply input terminal 36 of the slave power supply system 230 is connected with the energy storage module 240, the power supply output terminal 35 of the slave power supply system is connected with the slave communication interface 210, the slave clock circuit 250, and the slave control module 220 jointly, and the other end of the slave power supply system 230 is grounded to the ground 50. The slave power supply system 230 is used to transform the energy stored in the energy storage module 240 to the operating voltage needed by the slave machine 200 to supply to the slave communication interface 210, the slave clock circuit 250, and the slave control module 220. (5) One end of the slave clock circuit 250 is connected to the power supply output terminal 35 of the slave power supply system, receiving the operating voltage output by the slave power supply system 230; one end is connected to the slave control module 220, supplying operating clock signal to the slave control module 220; and the other end of the slave clock circuit 250 is grounded to the ground 50. 31 (6) The other end of the slave control module 220 is grounded to the ground 50. The advantages of the embodiment of the slave machine shown in FIG.13 lie in: Firstly, the use of the rectifier bridge circuit 260 has realized the polarity transform of the input power supply of the slave machine, which eliminates the connection polarity demands in the traditional network communication system and realizes the double-wire non-polarity connection between the master machine 100 and the slave machine 200, therefore the connection process of the master-slave mode network system can be simplified and the possibility of the slave machine damage when powered resulting from connection mistakes in the network can be avoided. Secondly, the slave communication interface 210 and the rectifier bridge circuit 260 are connected in parallel between the two wires of the signal bus 300, which, on the one hand, avoids the effect on the data transmission speed between the master machine and the slave machine caused by the rectifier bridge circuit 260, on the other hand, makes the slave machine be able to receive the single-polarity modulation data as well as the dual-polarity modulation data. Thirdly, the energy storage module 240 in the slave machine 200 is used to store the energy supplied by the master machine 100, which makes the slave machine 200 passive, so the power supplied to the entire communication system can be supplied to the master machine 100 only, thus decreasing the complexity of power supply of the system, and improving the maintainability of the system. At the same time, the use of the energy storage module 240 also furthest keeps the stability of the slave power supply system 230 during the data transmission between the slave machine 200 and the master machine 100, therefore the stability of the entire communication system can be improved. As one embodiment of the slave communication interface 210 according to the present invention, the slave communication interface 210 includes a slave data modulation module 201 and a slave data demodulation module 202 which is comprised of two slave data demodulation circuits 212, as shown in FIG.14. The detailed connection is as follows: (1) The two slave data demodulation circuits 212 are respectively connected to the two wires of the signal bus 300, extracting the voltage change information on the signal bus 300 respectively. They are respectively connected to the slave control module 220, transmitting the data information to the slave control module 220 for further processing. Both of the two slave data demodulation circuits 212 are connected to the power supply output terminal 35 of the slave power supply system 230, receiving the operating power supplied by the slave power supply system 230 which renders that the voltage output to the slave control 32 module 220 is essentially the same as the operating voltage of the slave control module 220. The two slave data demodulation circuits 212 are also grounded to the ground 50 jointly. (2) One end of the slave data modulation module 201 is connected to the slave control module 220, one end is grounded to the ground 50, and the other two ends are connected to the signal bus 300 respectively. The slave data modulation module 201 is used to transform the data information output by the salve control module 220 and expressed in the form of high level or low level to the current consumption changes of the slave machine, and to load the current consumption changes upon the signal bus 300 to transmit to the master machine 100. The advantage of the embodiment of the slave communication interface 2 10 lies in: by using two slave data demodulation circuits 212 which are exactly the same, working independently, and connected to the signal bus 300 respectively, the slave machine 200 can not only receive the single-polarity modulation data output by the master machine 100, but also the dual-polarity modulation data output by the master machine 100, which makes the slave machine 200 well adoptable and applicable in different systems with different communication requirements. The slave data modulation module 201 in the present invention can include a resistor 215, a resistor 216, a resister 217, an NMOS transistor 218, and an NMOS transistor 219, as shown in FIG.15. The drain and the substrate of the NMOS transistor 218, the drain and the substrate of the NMOS transistor 219, and one end of the resistor 215 are jointly grounded to the ground 50. The grid of the NMOS transistor 218, the grid of the NMOS transistor 219, and the other end of the resistor 215 connect together, and connect to the slave control module 220 together. The source of the NMOS transistor 218 is connected to one part of the signal bus 300 via the resistor 216, and the source of the NMOS transistor 219 is connected to the other part of the signal bus 300 via the resistor 217. Wherein, the resistor 215 is used to provide pull-down drive for the grid of the NMOS transistor 218 and NMOS transistor 219, and the resistor 216 and the resistor 217 are used to realize the transformation from the voltage change information to the current change information. The slave data modulation module 201 mentioned above realizes the function of loading the data to be sent upon the signal bus 300 in the form of current consumption changes, and the operating principle lies in: (1) When sending the data "1", the slave control module 220 outputs a control signal at high level, then the grid voltage of the NMOS transistor 218 and the NMOS transistor 219 will be high, and the NMOS transistor 218 and the NMOS transistor 219 will be on. At this moment, the current on the signal 33 bus 300 caused by the salve machine 200 is represented as the bus voltage divided by the sum of the resistances of the resistor 216 and the resistor 217, and the aforementioned current is much higher than the normal operating current of the slave machine 200. For example, if the electronic detonator is chosen as the slave machine 200, the current will be in milliampere level, while the normal operating current of the electronic detonator is in microampere level, which is convenient for the data demodulation module in the master machine to extract and identify the data information sent by the slave machine. (2) When sending the data "0", the slave control module 220 outputs a control signal at low level, the grid voltage of the NMOS transistor 218 and the NMOS transistor 219 will be low, and the NMOS transistor 218 and the NMOS transistor 219 will be cut off, then the current on the signal bus 300 caused by the slave machine 200 is represented as the normal operating current of the present slave machine 200. Based on the aforementioned operating principle, FIG.25-1 shows the voltage control signal output by the slave control module 220 which is the data information to be transmitted to the master communication interface. Via the slave data modulation module 201, the voltage control signal is transformed to the current consumption information which is then sent to the signal bus 300, as shown in FIG.25-2 as a reference. In FIG.25-1, Vcc represents the operating voltage of the slave machine 200. In FIG. 25-2, IH represents the consumed current when the slave machine 200 sends the data "1" to the master machine 100, and IL represents the consumed current when the slave machine 200 sends the data "0" to the master machine 100, that is, the normal operating current of the slave machine 200. The slave data demodulation circuit 212 in the present invention can include an inverter 303 and a resistor 206, as shown in FIG. 16. The inverter 303 is used to extract the data information of the signal bus 300, one end of the inverter 303 is connected to the power supply output terminal 35 of the slave power supply system 230, and one end is grounded to the ground 50. The signal input terminal of the inverter 303 is connected to one part of the signal bus 300, and this terminal is also grounded to the ground 50 via the resistor 206; the signal output terminal of the inverter 303 is connected to the slave control module 220. Wherein, the resistor 206 is used to provide pull-down drive for the signal input terminal of the inverter 303, which prevents the signal input terminal of the inverter 303 from an indefinite state when the signal bus 300 is disconnected accidentally, thus improving the reliability of the communication system; meanwhile, because of the function of pull-down of the resistor 206, the energy consumption of the energy storage module 240 when the signal input terminal of the inverter 303 is in an indefinite state is decreased, therefore improving the efficient 34 utilization rate of the energy stored in the slave machine. Furthermore, when the data of the bus 300 change, the resistor 206 also provides a discharging channel for the residual charge on the bus 300, thus improves the communication speed. The slave data demodulation circuit 212 in the present invention can also include an inverter 304 and an NMOS transistor 207, as shown in FIG.17. One end of the inverter 304 is connected with the power supply output terminal 35 of the slave power supply system 230, and one end is grounded to the ground 50. The NMOS transistor 207 provides negative feedback to the signal input terminal of the inverter 304. The source and the substrate of the NMOS transistor 207 is grounded to the ground 50; its drain and the signal input terminal of the inverter 304 connect together, and they are connected to one part of the signal bus 300; and the grid of the NMOS transistor 207 and the signal output terminal of the inverter 304 connect together, and are connected to the slave control module 220 jointly. The pull-down resistor 206 is replaced by the NMOS transistor 207 which is connected in the way of negative feedback in the slave data demodulation circuit 212 mentioned above. The advantage is to avoid the consumption of the energy supplied by the master machine 100 caused by the resistor 206, and to improve the utilization efficiency of the energy provided by the master machine. In addition, with the characteristic of dynamic resistance of an NMOS transistor, when the input of the bus 300 is at low level, the output of the inverter 304 will be at high level, and the NMOS transistor 207 will be in the state of conduction; while the input of the bus 300 is at high level, the output of the inverter 304 will be at low level, and the NMOS transistor 207 will be in the state of cutoff. When the voltage on the bus changes from high level to low level, the output voltage of the invertor 304 will change from low level to high level accordingly, and the grid voltage of the NMOS transistor 207 will change from low level to high level accordingly. During the process, the NMOS transistor 207 enters the saturation-conduction region from the cut-off region through the variable resistance region, and gradually releases the residual charge of the bus. While the bus 300 is disconnected by accident, the input terminal of the inverter 304 will be in a definite state at low level due to the existence of the NMOS transistor 207. For the single-polarity modulation data output by the single-polarity communication interface circuit, taking the modulation data expressed in the waveform shown in FIG.23-1 as an example, the output of the two slave data demodulation circuits 212 can be respectively represented as the waveforms shown in FIG.23-2 and FIG.23-3. In FIG.23-2 and FIG.23-3, Vcc represents the operating voltage of the slave machine 200. The slave data demodulation module 35 202 demodulates the single-polarity modulation data shown in FIG.23-1 into two paths of signals, one of which shown in FIG.23-2 represents the impulse signal changing between the operating voltage Vcc and the zero voltage correspondingly to the change of the modulation signal input to the slave data demodulation circuit 212, while the other of which shown in FIG.23-3 represents the zero voltage signal. For the dual-polarity modulation data output by the dual-polarity communication interface circuit, taking the modulation data expressed in the waveform shown in FIG.24-1 as an example, the output of the two slave data demodulation circuits 212 can be respectively represented as the waveforms shown in FIG.24-2 and FIG.24-3. In FIG.24-2 and FIG.24-3, VcC represents the operating voltage of the slave machine 200. The slave data demodulation module 202 demodulates the dual-polarity data shown in FIG.24-1 into two paths of signals, one of which shown in FIG.24-2 represents the impulse signal changing between the operating voltage Vcc and the zero voltage oppositely to the change of the input modulation signal, while the other of which shown in FIG.24-3 represents the impulse signal changing between the operating voltage VcC and the zero voltage correspondingly to the change of the input modulation signal. The inverter 303 and the inverter 304 in the two embodiments of the slave data demodulation circuit 212 mentioned above are preferred to be a Schmitt inverter, thereby whether state switching of the signal input to the inverter is slow or not, that is, whether the transition time for the level switching is long or not, the output edge of the inverter will be relatively steep and the transition time for the level switching will be extremely short, which shortens the state-transition time of follow-up processing circuits of the slave data demodulation circuit 212 and reduces the power consumption of the slave machine 200. In addition, the Schmitt inverter has good anti-noise performance, which can improve the stability of the function of data receiving of the slave machines 200. The cooperation of the master machine 100 and the slave machine 200 in the master-slave mode direct current carrier communication system mentioned above has realized a two-wire non-polarity master-slave mode direct current carrier communication system in which the simplex and bidirectional data transmission is realized during the process that the master machine supplies power to the slave machines. In the aforementioned embodiments of the master machine 100, the master power supply system 130 supplies only one path of communication voltage VIN to the master communication interface 150, so when the master machine 100 sends data to the slave machine 200 or the master machine 100 receives data from the slave machines 200, the voltage of the signal bus 300 will 36 maintain the communication voltage VIN all the time. Actually, based on the embodiment of the master machine shown in FIG.2, the present invention can be further improved as follows: the communication voltage output terminal 32 of the master power supply system 130 is further divided into a transmitting voltage output terminal 34 and a receiving voltage output terminal 33; and the communication voltage input terminal 51 of the master communication interface 151 is further divided into a transmitting voltage input terminal 52 and a receiving voltage input terminal 53, as shown in FIG.18. The transmitting voltage output terminal 34 of the master power supply system 130 is connected to the transmitting voltage input terminal 52 of the master communication interface 151; the receiving voltage output terminal 33 of the master power supply system 130 is connected to the receiving voltage input terminal 53 of the master communication interface 151. In this embodiment, the master machine 100 transmits or receives data under different voltages, thereby improving the Signal-to-Noise ratio during the process that the master machine 100 receives data from the slave machines 200, therefore the communication accuracy of the master-slave mode direct current carrier communication system including the master machine in this embodiment is improved. As an embodiment according to the technical solution shown in FIG.18, the master machine 100 includes a master clock circuit 140, a master power supply system 130, a master communication interface 1511 and a master control module 120. The master communication interface 1511 can further be comprised of an electronic switch 121 and a master communication interface circuit 153, as shown in FIG.19. Two input terminals of the electronic switch 121 lead to the exterior of the master communication interface 1511, forming the transmitting voltage input terminal 52 and the receiving voltage input terminal 53 respectively; the output terminal of the electronic switch 121 is connected to the terminal 20 of the master communication interface circuit 153; the control terminal of the electronic switch 121 is connected to the master control module 120, and the master control module 120 controls the electronic switch 121 to choose which voltage should be output to the master communication interface circuit 153. The master communication interface circuit 153 still includes one end being grounded to the ground 40, and another end connecting to the operating voltage output terminal 31 of the master power supply system 130 to receive the operating voltage supplied by the master power supply system 130. The master communication interface circuit 153 still has two ends leading to the exterior of the master communication interface 1511 respectively to form the signal bus 300. The other end of the master communication interface circuit 153 is connected to the master control 37 module 120. The electronic switch 121 mentioned in the above embodiment accomplishes the switching between the transmitting voltage and the receiving voltage under the control of the master control module 120: when the master machine 100 transmits data to the slave machine 200, or the master machine 100 supplies operating power to the slave machine 200, the master control module 120 sends a control signal expressing that the transmitting voltage should be output to the control terminal of the electronic switch 121, which conducts the branch circuit in which the electronic switch 121 connects to the transmitting voltage output terminal 34, then the terminal 20 of the master communication interface circuit 153 connects to the transmitting voltage output terminal 34 of the master power supply system 130, thus the voltage of the signal bus 300 will be the transmitting voltage. Contrarily, when the master machine 100 receives data from the slave machine 200, the master control module 120 sends a control signal expressing that the receiving voltage should be output to the control terminal of the electronic switch 121, which conducts the branch circuit in which the electronic switch 121 is connected to the receiving voltage output terminal 33, then the terminal 20 of the master communication interface circuit 153 is connected to the receiving voltage output terminal 33 of the master power supply system 130, thus the voltage of the signal bus 300 will be the receiving voltage. The single-polarity communication interface circuit shown in FIG.4, FIG.5 or FIG.6, or the dual-polarity communication interface circuit shown in FIG.8, FIG.9 or FIG.Il can be chosen to be the master communication interface circuit 153 in the embodiment shown in FIG. 19. As another embodiment of the technical solution shown in FIG. 18, the master machine 100 includes a master clock circuit 140, a master power supply system 130, a master communication interface 1512 and a master control module 120. Wherein, the single-polarity communication interface shown in FIG.20 which is comprised of a single-polarity data modulation module 1012, a single-polarity data demodulation module 102 and an electronic switch 123, and the dual-polarity communication interface shown in FIG.22 which is comprised of a dual-polarity data modulation module 105 1, a dual-polarity data demodulation module 106 and an electronic switch 125 can be chosen as the master communication interface 1512 according to the embodiment. The detailed connection can be described as follows: (1) One end of the single-polarity/dual-polarity data modulation module is grounded to the ground 40; one end is connected with the the single-polarity/dual-polarity data demodulation module, and jointly connect to the operating voltage output terminal 3 1 of the master power 38 supply system 130 to receive the steady operating voltage output by the master power supply system 130. The single-polarity/dual-polarity data modulation module still has one end connecting with the master control module 120 to receive the data information output by the master control module 120. The modulation signal input terminal of the single-polarity/dual-polarity data modulation module is connect with the transmitting voltage output terminal 34 of the master power supply system 130, forming the transmitting voltage input terminal 52 of the master communication interface 15 12 to receive the transmitting voltage output by the master power supply system 130. The other two ends of the single polarity/dual-polarity data modulation module: one end leads to the exterior of the master communication interface 1512, forming one part of the signal bus 300; the other end is connected to one input terminal of the electronic switch, forming the transmitting voltage branch circuit of the electronic switch, when the master machine is to transmit data to the slave machine 200, the electronic switch will choose the transmitting voltage of this branch circuit to output to the signal bus 300 under the control of the master control module 120. (2) One end of the single-polarity/dual-polarity data demodulation module is connected to the ground 40; one end is connected with the master control module 120, transmitting the received data information to the master control module 120 for processing; one end is connected with the operating voltage output terminal 31 of the master power supply system 130 to receive the operating voltage output by the master power supply system 130; one end is connected with the receiving voltage output terminal 33 of the master power supply system 130, forming the receiving voltage input terminal 53 of the master communication interface 1512; the other end is connected with the other input terminal of the electronic switch, forming the receiving voltage branch circuit of the electronic switch, and when the master machine is to receive data from the slave machine, the electronic switch will choose the receiving voltage of this branch circuit to output to the signal bus 300 under the control of the master control module 120. (3) The two input terminals of the electronic switch: one terminal is connected with the single-polarity/dual-polarity data modulation module, the other terminal is connected with the single-polarity/dual-polarity data demodulation module, and the choice of the voltage output to the signal bus 300 is controlled by the master control module 120. The output terminal of the electronic switch leads to the exterior of the master communication interface 1512, forming the other part of the signal bus 300; and the control terminal of the electronic switch is connected with the master control module 120. In the embodiments of the master communication interface 1512 39 shown in FIG.20 and FIG.22, the single-polarity/dual-polarity data modulation module is directly connected to the transmitting voltage output terminal 34 of the master power supply system 130, the single-polarity/dual-polarity data demodulation module is directly connected to the receiving voltage output terminal 33 of the master power supply system 130; the electronic switch realizes the switching of the voltage output to the signal bus 300 under the control of the master control module 120. When the master machine 100 transmits data to the slave machine 200, the master control module 120 sends a control signal expressing that the transmitting voltage should be output to the control terminal of the electronic switch, which conducts the branch circuit in which the electronic switch connects to the single-polarity/dual-polarity data modulation module, thus the voltage on the signal bus 300 will be represented as the transmitting voltage. Contrarily, when the master machine 100 receives data from the slave machine 200, the master control module 120 sends a control signal expressing that the receiving voltage should be output to the control terminal of the electronic switch, which conducts the branch circuit that the electronic switch connects to the single-polarity/dual-polarity data demodulation module, thus the voltage on the signal bus 300 will be represented as the receiving voltage. In the embodiment of the single-polarity communication interface shown in FIG.20, the single-polarity data modulation module 1012 includes a driving module 112 and an electronic switch 124, as shown in FIG.21, The detailed connection is as follows: (1) One end of the driving module 112 is connected to the operating voltage output terminal 31 of the master power supply system 130 to receive the operating voltage output by the master power supply system 130 and to supply low driving voltage to the driving module 112. The signal input terminal of the driving module 112 is connected with the master control module 120 to receive the low level control signal output by the master control module 120. The signal output terminal of the driving module 112 is connected with the control terminal of the electronic switch 124, transforming the received low level control signal to the high level control signal to output in order to control the electronic switch 124 choosing which branch circuit to conduct. One end of the driving module 112 and one input terminal of the electronic switch 124 jointly lead to the exterior of the single-polarity data modulation module 1012, forming the modulation signal input terminal 12. The other end of the driving module 112 and the other input terminal of the electronic switch 124 are jointly grounded to the ground 40, and lead to the exterior of the single-polarity data modulation module 1012, forming one part of the signal bus 300. (2) The control terminal of the electronic switch 124 is connected 40 to the signal output terminal of the driving module 112 to receive the control signal at high level output by the driving module 112. The output terminal of the electronic switch 124 leads to the exterior of the single-polarity data modulation module 1012, forming the modulation signal output terminal 11 and connecting to one input terminal of the electronic switch 123. One of the two input terminals of the electronic switch 124 is grounded to the ground 40 together with the driving module 112, and also leads to the exterior of the single-polarity data modulation module 1012 to form one part of the two wires of the signal bus 300; the other input terminal of the electronic switch 124 leads to the exterior of the single-polarity data modulation module 1012 together with the driving module 112, forming the modulation signal input terminal 12 which is used to receive the higher communication voltage supplied by the master power supply system 130 to the single-polarity data modulation module 1012 and to supply high driving voltage for the driving module 112. The operating principle of the single-polarity data modulation module 1012 mentioned above is nearly the same as the operating principle of the single-polarity data modulation module 1011 shown in FIG.7. In addition, in the embodiment of the dual-polarity communication interface shown in FIG.22, the composition, the connection and the operating principle of the dual-polarity data modulation module 1051 are nearly the same as the embodiment shown in FIG.10. The master machine 100 according to the present invention can send single-polarity modulation data or dual-polarity modulation data to the slave machine 200 via the signal bus 300, and the instructions that the master machine 100 sends to the slave machine 200 can be global instructions or single instructions. The global instructions are sent to all the slave machines in the communication system. Generally, when receiving a global instruction, every slave machine will perform the corresponding operations respectively without returning any information to the master machine. While single instructions are sent to a certain slave machine in the communication system. Generally, when receiving a single instruction, the slave machine will perform the corresponding operations and then return the operating results to the master machine. The FIG.26 shows the voltage waveform on the signal bus 300 when the master machine 100 shown in FIG.18 is sending a single-polarity global instruction to the slave machines 200. After sending the global instruction to slave machines 200 under the transmitting voltage VTXD, the master machine 100 returns to the state of charging the slave machines 200. If the master machine 100 sends a 41 single instruction to a slave machine 200 under the transmitting voltage VTXD, the master machine 100 will enter the state of supplying energy for the slave machine 200 after the single instruction transmitting is completed, and maintain the state for a predetermined time T to supply the consumed energy in the energy storage module 240 at the internal of the slave machine caused by the slave machine when receiving low level data. Because what the master machine has sent is a single instruction for a certain slave machine, after completing supplying power to the energy storage module 240 in the slave machine, the master machine 100 will switch the voltage on the signal bus 300 to the receiving voltage VRXD to wait for the data retuned by the slave machine 200, and only after the date are received completely, the master machine can return to the state of charging the slave machines. The variable VTXD shown in FIG.26 represents the voltage output by the transmitting voltage output terminal 34 of the master power supply system 130, and the variable VRXD represents the voltage output by the receiving voltage output terminal 33 of the master power supply system 130. FIG.27 shows the voltage waveform on the signal bus 300 when the master machine 100 shown in FIG.18 is sending a dual-polarity single instruction to the slave machine 200. The principle is nearly the same as the principle that the master machine sends a single-polarity single instruction mentioned above, the master machine 100 sends a single instruction to the slave machine 200 under the voltage VrXD, and after the predetermined charging time T, the master machine 100 switches the voltage on the signal bus 300 to the receiving voltage VRXD to wait for the data information returned by the slave machine 200, and after the date are received completely, the master machine will return to the state of charging the slave machines. If the master machine 100 sends a global instruction to all the slave machines 200, after completing the instruction transmitting, the master machine will directly return to the state of charging the slave machines without receiving the data from the slave machines. The communication voltage output terminal 32 of the master power supply system according to the present invention can be further divided into a transmitting voltage output terminal 34 and a receiving voltage output terminal 33, and it is a preferred choice that the voltage output by the transmitting voltage output terminal 34 is higher than the voltage output by the receiving voltage output terminal 33, the advantages of which lie in: When the master machine 100 is in a state of non-communication and data transmitting, the master machine 100 will output higher transmitting voltage to the signal bus 300 in order to supply charging power for the energy storage module 240 at the internal of the slave machine 200. While the master machine 100 is to receive data sent by the slave machine 200, if the master 42 machine 100 still outputs higher transmitting voltage to the signal bus 300, the energy storage module 240 in the salve machine 200 will continue obtaining charging energy from the signal bus 300, then current noise will be generated on the signal bus 300, and it will decrease the Signal-to-Noise ratio during the process that the master machine is receiving data. Contrarily, when the master machine 100 is receiving data from the slave machine 200, if the voltage output to the signal bus 300 by the master machine 100 is decreased to make the voltage on the bus 300 lower than the voltage of the energy storage module 240 in the slave machine 200, all the slave machines 200 in the network will be powered by their own respective energy storage module 240 to keep itself operating. So when the master machine receives data, the current noise generated from the process that the slave machines 200 obtain charging energy from the signal bus 300 can be avoided, therefore the Signal-to-Noise ratio during the process of data transmitting of the slave machine will be increased, and the reliability of data receiving of the master machine can be improved. The master machine shown in FIG. 18 and its detailed embodiments can be cooperated with the slave machine according to the present invention to realize the technical purpose of the present invention. After the slave machine receives the data sent by the master machine according to the invention, the slave data demodulation module 202 at the internal of the slave machine will demodulate the data and output the demodulated data to the slave control module 220 for further processing. If the data is single-polarity data, the waveforms of the output demodulated data are nearly the same as the waveforms shown in FIG.23-2 and FIG.23-3; and if the data is dual-polarity data, the waveforms of the output demodulated date are nearly the same as the waveforms shown in FIG.24-2 and FIG.24-3. The master-slave mode direct current carrier communication system according to the present invention can be used in the electronic detonator initiation network. Concretely say, the master machine 100 according to the present invention can be represented as the electronic initiation device, and the slave machine 200 can be represented as the electronic detonator. When the technical solution of the present invention is used in a communication system with high fatalness such as the electronic detonator initiation network, it is a preferred choice that the communication voltage is lower than the operating voltage output by the master power supply system 130, which is beneficial to improve the security during the communication process of the system according to the present invention. 43

Claims

1. A master machine in a master-slave mode direct current carrier communication system which is comprised of a master machine, at least one slave machine, and signal bus used to connect the slave machine with the master machine, and the slave machine is connected in parallel between the signal bus extending from the master machine, wherein: the master machine includes a master clock circuit, a master power supply system, a master communication interface, and a master control module, the master clock circuit, the master power supply system, the master communication interface, and the master control module are all grounded to the ground one respectively; the operating voltage output terminal of the master power supply system is connected with the master communication interface, the master clock circuit, and the master control module; the other end of the master power supply system is the communication voltage output terminal leading to the communication voltage input terminal of the master communication interface; the master communication interface further includes two ends leading to the exterior of the master machine respectively, forming the signal bus; other ends of the master communication interface connect to the master control module; and the other end of the master clock circuit is connected with the master control module.

2. The master machine according to claim 1, wherein: the master communication interface is a master communication interface circuit, a first terminal of the master communication interface circuit is connected to the communication voltage output terminal, forming the communication voltage input terminal of the master communication interface.

3. The master machine according to claim 1, wherein: the communication voltage output terminal is subdivided into a transmitting voltage output terminal and a receiving voltage output terminal; the communication voltage input terminal is subdivided into a 44 transmitting voltage input terminal and a receiving voltage input terminal; the transmitting voltage output terminal of the master power supply system is connected to the transmitting voltage input terminal of the master communication interface; and the receiving voltage output terminal of the master power supply system is connected to the receiving voltage input terminal of the master communication interface.

4. The master machine according to claim 3, wherein: the master communication interface is comprised of a first electronic switch and the master communication interface circuit; two input terminals of the first electronic switch lead to the exterior of the present master communication interface, forming the transmitting voltage input terminal and the receiving voltage input terminal respectively; the output terminal of the first electronic switch is connected to the first terminal of the master communication interface circuit; the control terminal of the first electronic switch is connected to the master control module; and the master communication interface circuit still includes another end which is connected to the operating voltage output terminal of the master power supply system, one end of the master communication interface circuit is grounded to the ground one, two ends of the master communication interface circuit lead to the exterior of the master communication interface respectively to form the signal bus, and the other end of the master communication interface circuit is connected to the master control module.

5. The master machine according to claim 2 or claim 4, wherein: the master communication interface circuit is a single-polarity communication interface circuit which includes a single-polarity data modulation module and a single-polarity data demodulation module, both the single-polarity data modulation module and the single-polarity data demodulation module are connected to the operating voltage output terminal of the master power supply system; they are both grounded to the ground one; and each of them includes another end which connects to the master control module respectively; the modulation signal input terminal of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface circuit, forming the first terminal of the master communication interface circuit; the modulation signal output terminal 45 of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface circuit via the single-polarity data demodulation module, forming one part of the signal bus; and the ground leads to the exterior of the single-polarity communication interface circuit, forming the other part of the signal bus.

6. The master machine according to claim 2 or claim 4, wherein: the master communication interface circuit is a single-polarity communication interface circuit which includes a single-polarity data modulation module and a single-polarity data demodulation module, the single-polarity data modulation module and the single-polarity data demodulation module are both connected to the operating voltage output terminal of the master power supply system; they are both grounded to the ground one; and each of them includes another end connecting to the master control module respectively; and the modulation signal input terminal of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface circuit via the single-polarity data demodulation module, forming the first terminal; and the ground and the modulation signal output terminal of the single-polarity data modulation module respectively lead to the exterior of the single-polarity communication interface circuit, forming the signal bus.

7. The master machine according to claim 2 or claim 4, wherein: the master communication interface circuit is a single-polarity communication interface circuit including a single-polarity data modulation module and a single-polarity data demodulation module, the single-polarity data modulation module and the single-polarity data demodulation module are both connected to the operating voltage output terminal of the master power supply system; they are both grounded to the ground one; and each of them includes another end connecting to the master control module respectively; and the modulation signal input terminal of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface circuit, forming the first terminal; the modulation signal output terminal of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface circuit, forming one part of the signal bus; and the other end of the single-polarity data demodulation module leads to the exterior of the single-polarity communication interface circuit, forming the other part 46 of the signal bus.

8. The master machine according to claim 5, claim 6 or claim 7, wherein: the single-polarity data modulation module includes a first driving module and a second electronic switch, one end of the first driving module is connected to the operating voltage output terminal of the master power supply system, one end of the first driving module and one input terminal of the second electronic switch are both grounded to the ground one; the signal input terminal of the first driving module is connected with the master control module; the signal output terminal of the first driving module is connected with the control terminal of the second electronic switch; and the other end of the first driving module and the other input terminal of the second electronic switch jointly lead to the exterior of the single-polarity data modulation module, forming the modulation signal input terminal of the single-polarity data modulation module; and the output terminal of the second electronic switch leads to the exterior of the single-polarity data modulation module, forming the modulation signal output terminal of the single-polarity data modulation module.

9. The master machine according to claim 3, wherein: the master communication interface is a single-polarity communication interface including a single-polarity data modulation module, a single-polarity data demodulation module, and a third electronic switch, the single-polarity data modulation module and the single-polarity data demodulation module are jointly connected to the operating voltage output terminal of the master power supply system, and they are jointly grounded to the ground one; and each of them further includes one end connecting to the master control module respectively; the modulation signal input terminal of the single-polarity data modulation module leads to the exterior of the single-polarity communication interface and further connects to the transmitting voltage output terminal of the master power supply system, forming the transmitting voltage input terminal of the single-polarity communication interface; the modulation signal output terminal of the single-polarity data modulation module is connected to one input terminal of the third electronic switch; the other end of the 47 single-polarity data modulation module leads to the exterior of the single-polarity communication interface, forming one part of the signal bus; the single-polarity data demodulation module further includes one end which is connected to the receiving voltage output terminal of the master power supply system, forming the receiving voltage input terminal of the single-polarity communication interface; the other end of the single-polarity data demodulation module is connected to the other input terminal of the third electronic switch; and the control terminal of the third electronic switch is connected with the master control module; and the output terminal of the third electronic switch leads to the exterior of the single-polarity communication interface, forming the other part of the signal bus.

10. The master machine according to claim 9, wherein: the single-polarity data modulation module includes a second driving module and a fourth electronic switch, one end of the second driving module is connected to the operating voltage output terminal of the master power supply system; the signal input terminal of the second driving module is connected with the master control module; the signal output terminal of the second driving module is connected with the control terminal of the fourth electronic switch; one end of the second driving module and one input terminal of the fourth electronic switch jointly lead to the exterior of the single-polarity data modulation module, forming the modulation signal input terminal of the single-polarity data modulation module; the other end of the second driving module and the other input terminal of the fourth electronic switch are jointly grounded to the ground one, and lead to the exterior of the single-polarity data modulation module, forming one part of the signal bus; and the output terminal of the fourth electronic switch leads to the exterior of the single-polarity data modulation module, forming the modulation signal output terminal of the single-polarity data modulation module.

11. The master machine according to claim 2 or claim 4, wherein: the master communication interface circuit is a dual-polarity communication interface circuit which includes a dual-polarity data modulation module and a dual-polarity data demodulation module, the dual-polarity data modulation module and the dual-polarity 48 data demodulation module are both connected to the operating voltage output terminal of the master power supply system and they are both grounded to the ground one; and each of them also have one end connecting to the master control module respectively; and the modulation signal input terminal of the dual-polarity data modulation module leads to the exterior of the dual-polarity communication interface circuit, forming the first terminal; one of the two modulation signal output terminals of the dual-polarity data modulation module leads to the exterior of the dual-polarity communication interface circuit via the dual-polarity data demodulation module, forming one part of the signal bus, and the other one directly leads to the exterior of the dual-polarity communication interface circuit, forming the other part of the signal bus.

12. The master machine according to claim 2 or claim 4, wherein: the master communication interface circuit is a dual-polarity communication interface circuit including a dual-polarity data modulation module and a dual-polarity data demodulation module, the dual-polarity data modulation module and the dual-polarity data demodulation module are both connected to the operating voltage output terminal of the master power supply system, and they are both grounded to the ground one; and both of them also have one end connecting to the master control module respectively; and the modulation signal input terminal of the dual-polarity data modulation module leads to the exterior of the dual-polarity communication interface circuit via the dual-polarity data demodulation module, forming the first terminal; and the two modulation signal output terminals of the dual-polarity data modulation module both lead to the exterior of the dual-polarity communication interface circuit respectively, forming the signal bus.

13. The master machine according to claim 3, wherein: the master communication interface is a dual-polarity communication interface including a dual-polarity data modulation module, a dual-polarity data demodulation module and a fifth electronic switch, the dual-polarity data modulation module and the dual-polarity data demodulation module are both connected to the operating voltage output terminal of the master power supply system; they are both grounded to the ground one; and each of them also has one end 49 connecting to the master control module respectively; the modulation signal input terminal of the dual-polarity data modulation module leads to the exterior of the dual-polarity communication interface to connect to the transmitting voltage output terminal of the master power supply system, forming the transmitting voltage input terminal of the dual-polarity communication interface; one of the two modulation signal output terminals of the dual-polarity data modulation module is connected to one input terminal of the fifth electronic switch, and the other one leads to the exterior of the dual-polarity communication interface, forming one part of the signal bus; the dual-polarity data demodulation module also has one end connected to the receiving voltage output terminal of the master power supply system, forming the receiving voltage input terminal of the dual-polarity communication interface; the other end of the dual-polarity data demodulation module is connected to the other input terminal of the fifth electronic switch; and the control terminal of the fifth electronic switch is connected with the master control module; and the output terminal of the fifth electronic switch leads to the exterior of the dual-polarity communication interface, forming the other part of the signal bus.

14. The master machine according to claim 11, 12 or 13, wherein: the dual-polarity data modulation module includes a third driving module, a fourth driving module, a sixth electronic switch, a seventh electronic switch, and a first inverter, the two driving modules and the first inverter are all connected to the operating voltage output terminal of the master power supply system jointly, and they are also grounded to the ground one; the signal input terminal of the first inverter and the signal input terminal of the fourth driving module are jointly connected to the master control module; the signal output terminal of the first inverter is connected to the signal input terminal of the third driving module; the signal output terminal of the third driving module is connected to the control terminal of the sixth electronic switch; the signal output terminal of the fourth driving module is connected to the control terminal of the seventh electronic switch; and one input terminal of the sixth electronic switch, one input terminal of the seventh electronic switch, the other end of the third driving module, and the other end of the fourth driving module connect together, and lead to the exterior of the dual-polarity data modulation module 50 jointly, forming the modulation signal input terminal of the dual-polarity data modulation module; the other input terminal of the sixth electronic switch and the other input terminal of the seventh electronic switch are both grounded to the ground one; and the output terminals of the two electronic switches respectively lead to the exterior of the dual-polarity data modulation module, forming the two modulation signal output terminals of the dual-polarity data modulation module.

15. The master machine according to claim 2 or claim 4, wherein: the master communication interface circuit is a dual-polarity communication interface circuit which includes a dual-polarity data modulation module and a dual-polarity data demodulation module, the dual-polarity data modulation module and the dual-polarity data demodulation module are both connected to the operating voltage output terminal of the master power supply system; they are both grounded to the ground one, and each of them includes one end connecting to the master control module respectively; and the modulation signal input terminal of the dual-polarity data modulation module leads to the exterior of the dual-polarity communication interface circuit, forming the first terminal; the two modulation signal output terminals of the dual-polarity data modulation module respectively lead to the exterior of the dual-polarity communication interface circuit, forming the signal bus; and the other end of the dual-polarity data modulation module is connected to the dual-polarity data demodulation module.

16. The master machine according to claim 15, wherein: the dual-polarity data modulation module includes a fifth driving module, a sixth driving module, an eighth electronic switch, a ninth electronic switch, and a second inverter, the two driving modules and the second inverter are jointly connected to the operating voltage output terminal of the master power supply system, and they are also grounded to the ground one together; the signal input terminal of the second inverter and the signal input terminal of the sixth driving module are both connected to the master control module, the signal output terminal of the second inverter is connected to the signal input terminal of the fifth driving module; the signal output terminal of the fifth driving module is connected to the control terminal of the eighth electronic switch, the signal output terminal of the sixth driving module is connected to the control terminal of the ninth electronic switch; and 51 one input terminal of the eighth electronic switch, one input terminal of the ninth electronic switch, the other end of the fifth driving module, and the other end of the sixth driving module connect together, and they all lead to the exterior of the dual-polarity data modulation module, forming the modulation signal input terminal of the dual-polarity data modulation module; the other input terminal of the eighth electronic switch is connected with the other input terminal of the ninth electronic switch and is grounded to the ground one via the dual-polarity data demodulation module at the exterior of the dual-polarity data modulation module; and the output terminals of the two electronic switches respectively lead to the exterior of the dual-polarity data modulation module, forming the two modulation signal output terminals of the dual-polarity data modulation module.

17. The master machine according to claim 3 to claim 16, wherein: the voltage output by the transmitting voltage output terminal is higher than the voltage output by the receiving voltage output terminal.

18. A slave machine in a master-slave mode direct current carrier communication system which is comprised of a master machine, at least one slave machine, and signal bus used to connect the slave machine with the master machine, and the slave machine is connected in parallel between the signal bus extending from the master machine, wherein: the slave machine includes a slave communication interface, a rectifier bridge circuit, an energy storage module, a slave power supply system, a slave clock circuit, and a slave control module, the slave communication interface, the rectifier bridge circuit, the energy storage module, the slave power supply system, the slave clock circuit, and the slave control module are all grounded to the ground two; the power supply input terminal of the slave power supply system is connected with the energy storage module, the power supply output terminal of the slave power supply system is connected with the slave control module, the slave clock circuit and the slave communication interface respectively; the slave communication interface and the rectifier bridge circuit each include two ends which lead to the exterior of the slave machine and connect to the signal bus respectively; the other end of the slave communication interface connects to the slave control module; the other end of the rectifier bridge circuit is connected to the energy storage module; and 52 the other end of the slave clock circuit is connected to the slave control module.

19. The slave machine according to claim 18, wherein: the slave communication interface includes a slave data modulation module and a slave data demodulation module which is comprised of two slave data demodulation circuits, the two slave data demodulation circuits are respectively connected to the two parts of the signal bus, they are respectively connected to the slave control module, both of them are connected to the power supply output terminal of the slave power supply system, and they are grounded to the ground two jointly; and one end of the slave data modulation module is connected with the slave control module, one end is grounded to the ground two, and the other two ends are respectively connected to the two parts of the signal bus.

20. The slave machine according to claim 19, wherein: the slave data modulation module includes a first resistor, a second resistor, a third resister, a first NMOS transistor, and a second NMOS transistor, the drain and the substrate of the first NMOS transistor, the drain and the substrate of the second NMOS transistor, and one end of the first resistor are jointly grounded to the ground two; the grid of the first NMOS transistor, the grid of the second NMOS transistor, and the other end of the first resistor connect together, and connect to the slave control module together; the source of the first NMOS transistor is connected to one part of the signal bus via the second resistor, and the source of the second NMOS transistor is connected to the other part of the signal bus via the third resistor.

21. The slave machine according to claim 19, wherein: the slave data demodulation circuit includes a third inverter and a fourth resistor, one end of the third inverter is connected to the power supply output terminal of the slave power supply system; the signal input terminal of the third inverter is connected to one part of the signal bus, and this terminal is also grounded to the ground two via the fourth resistor; the signal output terminal of the third inverter is connected to 53 the slave control module; and the other end of the third inverter is grounded to the ground two directly.

22. The slave machine according to claim 19, wherein: the slave data demodulation circuit includes a fourth inverter and a third NMOS transistor, one end of the fourth inverter is connected with the power supply output terminal of the slave power supply system, one end of the fourth inverter is grounded to the ground two; and the source and the substrate of the third NMOS transistor is grounded to the ground two; its drain and the signal input terminal of the fourth inverter connect together, and are connected to one part of the signal bus; and the grid of the third NMOS transistor and the signal output terminal of the fourth inverter connect together, and are connected to the slave control module jointly.

23. A master machine in a master-slave mode direct current carrier communication system substantially as hereinbefore described with reference to the accompanying drawings.

24. A slave machine in a master-slave mode direct current carrier communication system substantially as hereinbefore described with reference to the accompanying drawings. 54