CN108108318B - TTL changes MBUS communication terminal - Google Patents
TTL changes MBUS communication terminal Download PDFInfo
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- CN108108318B CN108108318B CN201810071181.5A CN201810071181A CN108108318B CN 108108318 B CN108108318 B CN 108108318B CN 201810071181 A CN201810071181 A CN 201810071181A CN 108108318 B CN108108318 B CN 108108318B
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- 238000004891 communication Methods 0.000 title claims abstract description 119
- 238000012544 monitoring process Methods 0.000 claims abstract description 54
- 239000003990 capacitor Substances 0.000 claims description 30
- 238000002955 isolation Methods 0.000 claims description 18
- 230000005540 biological transmission Effects 0.000 abstract description 7
- 238000000034 method Methods 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- -1 heating Substances 0.000 description 2
- 238000011835 investigation Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000013480 data collection Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 210000001503 joint Anatomy 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- 238000013024 troubleshooting Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/38—Information transfer, e.g. on bus
- G06F13/382—Information transfer, e.g. on bus using universal interface adapter
- G06F13/385—Information transfer, e.g. on bus using universal interface adapter for adaptation of a particular data processing system to different peripheral devices
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F13/00—Interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F13/38—Information transfer, e.g. on bus
- G06F13/42—Bus transfer protocol, e.g. handshake; Synchronisation
- G06F13/4282—Bus transfer protocol, e.g. handshake; Synchronisation on a serial bus, e.g. I2C bus, SPI bus
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
- H03K19/0175—Coupling arrangements; Interface arrangements
- H03K19/017509—Interface arrangements
- H03K19/017536—Interface arrangements using opto-electronic devices
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2213/00—Indexing scheme relating to interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F2213/0002—Serial port, e.g. RS232C
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2213/00—Indexing scheme relating to interconnection of, or transfer of information or other signals between, memories, input/output devices or central processing units
- G06F2213/38—Universal adapter
- G06F2213/3852—Converter between protocols
Abstract
The invention discloses a TTL-to-MBUS communication terminal, which comprises a TTL serial port communication circuit, a voltage transmitting circuit, a current receiving circuit, an MBUS and monitoring switching circuit, an MBUS monitoring circuit and an MBUS interface; the method realizes TTL-MBUS communication, realizes compatible host voltage transmission and slave current reception by using a voltage transmitting circuit and a current receiving circuit, and monitors MBUS master-slave communication data in real time by using an MBUS and monitoring switching circuit and an MBUS monitoring circuit.
Description
Technical Field
The invention relates to the field of MBUS communication, in particular to a communication terminal for converting TTL into MBUS.
Background
RS485: also known as TIA-485-A, ANSI/TIA/EIA-485 or TIA/EIA-485. Is a standard defining the electrical characteristics of drivers and receivers in a multi-point communication system, which standard is defined by the telecommunications industry association and the electronic industry association.
MBUS: the data bus is specially used for transmitting information to consumption measuring instrument and counter, and is widely used for measuring instruments such as water meter, steam meter and heat meter.
Monitoring: all communication data on the MBUS bus were collected.
Along with the vigorous development and perfection of the national intelligent power grid, the meter reading workload and hardware repeated construction are reduced. The national power grid company mainly promotes the four-meter-in-one project, utilizes the existing collection platform of the power system to realize the integrated remote copying of public utility data such as water, electricity, heating, gas and the like, and aims to create a novel energy utilization service mode and comprehensively support the construction of smart cities. Because the water, heating, gas and other measuring instruments widely adopt the MBUS bus with a host computer and a plurality of slaves for communication, the hardware of the existing power acquisition platform has no corresponding communication interface, and meanwhile, has no simple and effective tool for monitoring the data on the MBUS communication bus in real time, a series of problems are brought to the reconstruction, debugging and problem investigation of the on-site power acquisition platform; the existing tool can not monitor the data on the bus at the same time, or can only monitor the data sent by the host computer, or can only monitor the data sent by the slave computer, thereby bringing inconvenience to the field MBUS communication fault investigation.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a TTL-to-MBUS communication terminal which is compatible with host voltage sending and slave current receiving and monitors MBUS master-slave communication data in real time.
The technical scheme adopted by the invention is as follows: the communication terminal from TTL to MBUS comprises a TTL serial port communication circuit, a voltage transmitting circuit, a current receiving circuit, an MBUS and monitoring switching circuit, an MBUS monitoring circuit and an MBUS interface; the output end of the TTL serial port communication circuit is connected with the input end of the voltage transmitting circuit, the output end of the current receiving circuit and the output end of the MBUS monitoring circuit are connected with the input end of the TTL serial port communication circuit, and the output end of the voltage transmitting circuit, the input end of the current receiving circuit and the MBUS are connected with the monitoring switching circuit; the output end of the MBUS and monitoring switching circuit is connected with the input end of the MBUS monitoring circuit; the MBUS is connected with the monitoring switching circuit and the MBUS interface.
Further, the TTL-to-MBUS communication terminal further comprises an electrical isolation circuit, the output end of the TTL serial port communication circuit is connected with the input end of the voltage transmitting circuit through the electrical isolation circuit, and the output end of the current receiving circuit and the output end of the MBUS monitoring circuit are connected with the input end of the TTL serial port communication circuit through the electrical isolation circuit.
Further, the electrical isolation circuit is an optocoupler.
Further, the TTL serial port communication circuit is an RS485 communication circuit or an RS232 communication circuit or a USB communication circuit.
Further, the voltage transmitting circuit comprises a first NPN triode, a second NPN triode and a first PNP triode; the output end of the TTL serial port communication circuit is connected with the base electrode of a first NPN triode, the emitter electrode of the first NPN triode is connected with the collector electrode of the first PNP triode and the emitter electrode of the second NPN triode, and the emitter electrode of the first NPN triode is grounded; the collector of the first NPN triode is connected with the base of the first PNP triode, the base of the first NPN triode, the emitter of the first PNP triode and the collector of the second NPN triode are connected with a power supply, and the emitter of the second NPN triode and the MBUS are connected with a monitoring switching circuit.
Further, the current receiving circuit comprises a first resistor, a second resistor, a third resistor, a first diode, a first polarity capacitor and a first comparator, the MBUS is connected with one end of the monitoring switching circuit and the first resistor and the positive electrode of the first diode, the other end of the first resistor is connected with the in-phase input end of the first comparator, the negative electrode of the first diode is connected with one end of the second resistor, the other end of the second resistor is connected with the inverting input end of the first comparator, one end of the third resistor and the positive electrode of the first polarity capacitor, the ground end of the first comparator, the negative electrode of the first polarity capacitor and the other end of the third resistor are grounded, and the output end of the first comparator is connected with the input end of the TTL serial port communication circuit.
Further, the MBUS monitoring circuit includes a fourth resistor, a fifth resistor, a sixth resistor, a second diode, a second polar capacitor and a second comparator, the MBUS is connected with one end of the monitoring switching circuit and the fourth resistor, the positive pole of the second diode, the other end of the fourth resistor is connected with the non-inverting input end of the second comparator, the negative pole of the second diode is connected with one end of the fifth resistor, the other end of the fifth resistor is connected with the inverting input end of the second comparator, the positive pole of the second polar capacitor and one end of the sixth resistor, the ground end of the second comparator, the negative pole of the second polar capacitor and the other end of the sixth resistor are grounded, and the output end of the second comparator is connected with the input end of the TTL serial port communication circuit.
Further, the MBUS and monitor switching circuit includes a third NPN triode, a fourth NPN triode, a third triode capacitor and a double pole double throw relay, the TTL serial port communication circuit is connected with a base and a collector of the third NPN triode, the collector of the third NPN triode is connected with a power supply, the collector of the third NPN triode is connected with the base of the fourth NPN triode and a positive pole of the third triode capacitor, a negative pole of the third triode capacitor is connected with an emitter of the third NPN triode, the emitter of the third NPN triode is connected with an emitter of the fourth NPN triode, the emitter of the third NPN triode is grounded, the collector of the fourth NPN triode is connected with a first coil connecting end of the double pole double throw relay, a second coil connecting end of the double pole double throw relay is connected with the power supply, a first normally closed contact and a first normally open contact of the double pole double throw relay are grounded, and a first movable contact of the double throw relay is connected with an MBUS interface; the second normally closed contact of the double-pole double-throw relay is connected with the input end of the MBUS monitoring circuit, the second normally open contact of the double-pole double-throw relay is connected with the output end of the voltage transmitting circuit and the input end of the current receiving circuit, and the second movable contact of the double-pole double-throw relay is connected with the MBUS interface.
The beneficial effects of the invention are as follows:
the invention relates to a TTL-to-MBUS communication terminal, which comprises a TTL serial port communication circuit, a voltage transmitting circuit, a current receiving circuit, an MBUS and monitoring switching circuit, an MBUS monitoring circuit and an MBUS interface; the method realizes TTL-MBUS communication, realizes compatible host voltage transmission and slave current reception by using a voltage transmitting circuit and a current receiving circuit, and monitors MBUS master-slave communication data in real time by using an MBUS and monitoring switching circuit and an MBUS monitoring circuit.
Drawings
The following is a further description of embodiments of the invention, taken in conjunction with the accompanying drawings:
FIG. 1 is a block diagram illustrating a TTL to MBUS communication terminal according to an embodiment of the present invention;
FIG. 2 is a schematic circuit diagram of an embodiment of a TTL serial port communication circuit, a voltage transmitting circuit, a current receiving circuit, and an MBUS monitoring circuit of a communication terminal from TTL to MBUS according to the present invention;
fig. 3 is a schematic circuit diagram of an embodiment of an MBUS and snoop switch circuit of a TTL-to-MBUS communication terminal according to the present invention.
Detailed Description
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other.
The TTL-to-MBUS communication terminal is arranged between host equipment and slave equipment and comprises a TTL serial port communication circuit, a voltage transmitting circuit, a current receiving circuit, an MBUS and monitoring switching circuit, an MBUS monitoring circuit and an MBUS interface; the TTL serial port communication circuit is connected with the host equipment; the output end of the TTL serial port communication circuit is connected with the input end of the voltage transmitting circuit, the output end of the current receiving circuit and the output end of the MBUS monitoring circuit are connected with the input end of the TTL serial port communication circuit, and the output end of the voltage transmitting circuit, the input end of the current receiving circuit and the MBUS are connected with the monitoring switching circuit; the output end of the MBUS and monitoring switching circuit is connected with the input end of the MBUS monitoring circuit; the MBUS is connected with the monitoring switching circuit and the MBUS interface, and the MBUS interface is connected with the slave equipment.
The TTL-MBUS communication terminal realizes TTL-MBUS communication between master and slave devices, realizes compatible host voltage transmission and slave current reception by using a voltage transmission circuit and a current receiving circuit, and monitors MBUS master-slave communication data in real time by using an MBUS and monitoring switching circuit and an MBUS monitoring circuit; specifically, master-slave communication of an MBUS bus is monitored, a master-slave mode exists on the whole communication line based on MBUS protocol requirements, communication modes of master and slave devices are different, the master is sent in a voltage mode, and the slave is sent in a current mode.
As a further improvement of the technical scheme, the TTL serial communication circuit is an RS485 communication circuit or an RS232 communication circuit or a USB communication circuit. In the invention, the TTL serial port communication circuit adopts an RS485 communication circuit. Referring to fig. 1, fig. 1 is a block diagram of a specific embodiment of a TTL-to-MBUS communication terminal according to the present invention, where the TTL-to-MBUS communication terminal further includes a power circuit, and the power circuit takes power from a mains supply (220V/AC) and outputs two power supplies through a switching power supply. One path provides power (5 VDC) for the RS485 communication circuit, and the other path provides power (36 VDC) for the voltage transmitting circuit, the current receiving circuit, the MBUS monitoring circuit, the MBUS and the monitoring switching circuit. By utilizing the RS485 communication circuit, because the hardware of the existing power acquisition platform is provided with the RS485 interface, when in site reconstruction, the terminal of the invention is only required to be in butt joint with the RS485 interface of the power acquisition platform, so that the communication requirements of water, heating, air and other metering instruments can be met, and the four-meter-in-one hardware platform reconstruction is completed; the equipment with the MBUS interface can be read only through the RS485 communication interface and the terminal. The communication equipment extends the host MBUS interface through an RS485 interface (as shown in figure 1, in actual use, the RS485 interface is that an RS485 communication circuit is connected with the host equipment through an RS485 bus); the MBUS interface (as shown in fig. 1, in actual use, the MBUS interface is connected with the slave device through the MBUS bus) may mount 125 slave device nodes. Referring to fig. 1 and fig. 2, fig. 2 is a schematic circuit diagram of a specific embodiment of a TTL serial port communication circuit, a voltage transmitting circuit, a current receiving circuit and an MBUS monitoring circuit of the communication terminal from TTL to MBUS, where the TTL serial port communication circuit is an RS485 communication circuit 1, and has a function of transmitting and receiving data, and the RS485 communication circuit 1 uses a special RS485 chip U2 and its peripheral circuit, performs half-duplex communication, and the chip U2 obtains data of an RS485 bus through the receiving circuit or transmits the data to the RS485 bus through a transmitting circuit.
As a further improvement of the technical scheme, referring to fig. 1, the TTL-to-MBUS communication terminal further includes an electrical isolation circuit, an output end of the TTL serial port communication circuit is connected with an input end of the voltage transmitting circuit through the electrical isolation circuit, and an output end of the current receiving circuit and an output end of the MBUS monitoring circuit are connected with an input end of the TTL serial port communication circuit through the electrical isolation circuit. Referring to fig. 2, the electrical isolation circuit is an optocoupler, specifically, two optocouplers are provided to electrically isolate the RS485 communication circuit from the voltage transmitting circuit and the current receiving circuit, which are respectively an optocoupler U3 and an optocoupler U5. The RS485 communication circuit is mainly isolated from electrical connection with the voltage transmitting circuit and the current receiving circuit, a series of communication interference caused by electrical difference of external connection equipment is reduced, and the anti-interference capability of the whole terminal is improved. The mbus_rx is at a high level, the optocoupler U5 is not turned on, the 4 th pin of the optocoupler U5 is at a high impedance to the ground, the current flowing through the resistor R10 is extremely small, the 4 th pin of the optocoupler U5 is approximately equal to vcc_485, the pnp triode Q2 cannot be turned on, the 2 nd pin and the 3 rd pin of the RS485 chip U2 are at a low level, and the RS485 chip U2 is in a receiving mode. MBUS_RX is low level, and opto-coupler U5 switches on, and opto-coupler U5 4 th foot is low impedance to ground, and the electric current that flows through resistance R10 becomes big, and opto-coupler U5 4 th foot voltage is equal to GND_485 approximately, PNP triode Q2 begins switching on, and RS485 chip U2) 2 nd foot, 3 rd foot are high level, and RS485 chip U2 is the transmission mode.
As a further improvement of the technical solution, referring to fig. 1 and 2, the voltage transmitting circuit 2 includes a first NPN transistor N1, a second NPN transistor N2, and a first PNP transistor Q1; the output end of the TTL serial communication circuit 1 is connected with the base electrode of a first NPN triode N1 through an electric isolation circuit (namely an optocoupler), the emitter electrode of the first NPN triode N1 is connected with the collector electrode of a first PNP triode Q1 and the emitter electrode of a second NPN triode N2, and the emitter electrode of the first NPN triode N1 is grounded; the collector of the first NPN triode N1 is connected to the base of the first PNP triode Q1, the base of the first NPN triode N1, the base of the first PNP triode Q1, the emitter of the first PNP triode Q1, the collector of the second NPN triode N2 are connected to a power supply, the emitter of the second NPN triode N2 and the MBUS are connected to a monitor switching circuit, and referring to fig. 3, fig. 3 is a schematic circuit diagram of a specific embodiment of an MBUS and monitor switching circuit of a TTL to MBUS communication terminal according to the present invention, and the voltage transmitting circuit 2 is connected to the monitor switching circuit through main MBUS and MBUS.
Referring to fig. 1 and 2, the voltage transmitting circuit 2 converts the TTL data signal into a voltage that meets the bus requirements of the MBUS. When the signal "1" is sent, the mbus_tx is at a high level, and drives the first NPN transistor N1 to be turned on, the collector C voltage of the first NPN transistor N1 is at a low level, the voltage vcc_mbus is divided by the resistors R19 and R22, and then the voltage of the base B of the first PNP transistor Q1 is pulled down, at this time, the first PNP transistor Q1 is turned on, and the voltage of the collector C of the first PNP transistor Q1 is approximately equal to the voltage 32V (vcc_mbus). The first NPN triode N1 is fully conducted, the voltage of the emitter E is about 0.7V smaller than the voltage of the base B and is about 31.3V (VCC_MBUS-0.7);
when the signal "0" is sent, the mbus_tx is at a low level, the first NPN transistor N1 is turned off, the voltage of the collector C of the first NPN transistor N1 is at a high level, and the voltage of the base B of the first PNP transistor Q1 is pulled up, and at this time, the first PNP transistor Q1 is completely turned off. After the voltage (VCC_MBUS) is divided by the resistors R20 and R8, 16V (VCC_MBUS/2) is generated at the base B of the first NPN triode N1. The first NPN triode N1 is fully conducted, and the voltage of the emitter E of the first NPN triode N1 is about 15.3V ((VCC_MBUS)/2-0.7) which is about 0.7V smaller than the voltage of the base B.
As a further improvement of the technical solution, referring to fig. 1 and 2, the current receiving circuit 3 includes a first resistor R1, a second resistor R2, a third resistor R3, a first diode D1, a first polarity capacitor C1 and a first comparator U4A, referring to fig. 3, the MBUS is connected to the monitor switching circuit and one end of the first resistor R1, the positive electrode of the first diode D1 (i.e. connected through the main MBUS), the other end of the first resistor R1 is connected to the non-inverting input end of the first comparator U4A, the negative electrode of the first diode D1 is connected to one end of the second resistor R2, the other end of the second resistor R2 is connected to the inverting input end of the first comparator U4A, one end of the third resistor R3, the positive electrode of the first polarity capacitor C1, the ground terminal of the first comparator U4A, the negative electrode of the first polarity capacitor C1, the other end of the third resistor R3 are grounded, and the output end of the first comparator U4A is connected to the input end of the TTL serial communication circuit 1 through the electrical isolation circuit. In summary, the current receiving circuit 3 is implemented by a comparator detection method. In normal, the voltage V1 is divided into (V1-0.1) V at the 2 nd pin of the first comparator U4A through the first diode D1, the second resistor R2 and the third resistor R3. At this time, the voltage V1 at the 3 rd pin of the first comparator U4A is greater than the non-inverting terminal (i.e., the 2 nd pin) of the first comparator U4A according to the comparator principle, the 1 st pin of the first comparator U4A is in a high-impedance state, and the first comparator U4A outputs a high level. When data is sent from the MBUS device, the MBUS bus is worn by about 20mA at maximum. After passing through the sampling resistor R15, a voltage change of about 0.2V is generated, and the voltage V1 becomes V1-0.2V. At this time, the voltage at the 3 rd pin of the first comparator U4A is V1-0.2V, the voltage at the 2 nd pin of the first comparator U4A is V1-0.1V, the non-inverting terminal (3 rd pin) of the first comparator U4A is smaller than the inverting terminal (2 nd pin) according to the comparator principle, and the 1 st pin of the first comparator U4A outputs a low level.
As a further improvement of the technical solution, referring to fig. 1 and 2, the MBUS listening circuit 4 includes a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a second diode D2, a second diode capacitor C2, and a second comparator U7A, the MBUS is connected to the listening switching circuit and one end of the fourth resistor R4, the anode of the second diode D2, referring to fig. 3, the MBUS is connected to the listening switching circuit through listening MBUS and MBUS listening circuits; the other end of the fourth resistor R4 is connected with the non-inverting input end of the second comparator U7A, the negative electrode of the second diode D2 is connected with one end of the fifth resistor R5, the other end of the fifth resistor R5 is connected with the inverting input end of the second comparator U7A, the positive electrode of the second diode capacitor C2 and one end of the sixth resistor R6, the grounding end of the second comparator U7A, the negative electrode of the second diode capacitor C2 and the other end of the sixth resistor R6 are grounded, and the output end of the second comparator U7A is connected with the input end of the TTL serial port communication circuit 1 through an electric isolation circuit. The MBUS monitoring circuit 4 is used for detecting voltage and current data, and uploading the voltage and current data to the host equipment for processing analysis through the electric isolation circuit and the TTL serial communication circuit 1 so as to complete monitoring of the voltage and current data. The MBUS listening circuit 4 is of similar design to the current receiving circuit 3.
Referring to fig. 1 and 2, when the master MBUS transmits a data signal "1" or the slave MBUS does not consume a bus current on the MBUS bus, the MBUS bus voltage is V2, and is divided to (V2-0.1) V at the 2 nd pin of the second comparator U7A through the second diode D2, the fifth resistor R5, and the sixth resistor R6. At this time, the voltage at the 3 rd pin of the second comparator U7A is V2, and according to the comparator principle, the non-inverting terminal (3 rd pin) of the second comparator U7A is larger than the inverting terminal (2 nd pin), the 1 st pin of the second comparator U7A is in a high-impedance state, and the second comparator U7A outputs a high level. When the host MBUS sends a data signal '0', the MBUS bus voltage is V2/2, and the voltage is divided into (V2/2) V at the 3 rd pin of the second comparator U7A through the fourth resistor R4. At this time, due to the second diode D2, the voltage at the 2 nd pin of the second comparator U7A is V2, the non-inverting terminal (3 rd pin) of the second comparator U7A is smaller than the inverting terminal (2 nd pin) according to the comparator principle, the 1 st pin of the second comparator U7A is in a low resistance state, and the second comparator U7A outputs a low level. When the slave MBUS on the MBUS bus consumes 20mA of bus current, the voltage change of about 0.2V is generated after the current passes through the sampling resistor of the MBUS bus, and the voltage V2 is changed into V2-0.2V. At this time, the 3 rd pin voltage V2-0.2V of the second comparator U7A, the 2 nd pin voltage V2-0.1V of the second comparator U7A, according to the comparator principle, the non-inverting terminal (3 rd pin) of the second comparator U7A is smaller than the inverting terminal (2 nd pin), and the 1 st pin of the second comparator U7A outputs a low level.
As a further improvement of the technical scheme, referring to fig. 1, 2 and 3, the MBUS and monitor switching circuit includes a third NPN triode N3, a fourth NPN triode N4, a third NPN capacitor C3 and a double-pole double-throw relay U1, the TTL serial port communication circuit 1 (i.e., RS 485_rx) is connected with the base and the collector of the third NPN triode N3, the collector of the third NPN triode N3 is connected with the power supply, the collector of the third NPN triode N3 is connected with the base of the fourth NPN triode N4 and the positive electrode of the third NPN capacitor C3, the negative electrode of the third NPN triode N3 is connected with the emitter of the third NPN triode N4, the emitter of the third NPN triode N3 is grounded, the collector of the fourth NPN triode N4 is connected with the first coil connection end of the double-pole double-throw relay U1, the second coil connection end of the double-pole double-throw relay U1 is connected with the power supply, the negative electrode of the third NPN triode N3 is connected with the emitter of the third NPN triode N4, the first normally-off contact (i.e., the first contact of the mbu 1 is connected with the double-pole bus); the second normally-closed contact (i.e. monitoring MBUS) of the double-pole double-throw relay U1 is connected with the input end of the MBUS monitoring circuit 4, the second normally-open contact (i.e. main MBUS) of the double-pole double-throw relay U1 is connected with the output end of the voltage transmitting circuit 2 and the input end of the current receiving circuit, and the second movable contact (i.e. bus MBUS+) of the double-pole double-throw relay U1 is connected with the MBUS interface.
In this embodiment, referring to fig. 1 to 3, the mbus and listening switch circuit is triggered when the receiving circuit signal RS485_rx of the RS485 communication circuit changes from high level to low level. When RS485_RX is high level, drive NPN triode N3 to switch on through resistance R16, NPN triode N3's collector C's voltage is low level, and at this moment NPN triode N4 cuts off, and double-pole double-throw relay U1 does not act, and double-pole double-throw relay U1's 2 nd foot and 3 rd foot short circuit at this moment, 6 th foot and 7 th foot short circuit monitor bus data communication. After the RS485_RX is changed from high level to low level, the NPN triode N3 is completely cut off, the voltage of the collector C of the NPN triode N3 is high level, and the voltage (VCC_485) charges the third polar capacitor C3 through the resistor R12 and the diode D4; at this time, the NPN triode N4 is turned on, resulting in the action of the double-pole double-throw relay U1, shorting the 4 th and 3 rd pins of the double-pole double-throw relay U1, shorting the 6 th and 5 th pins, and performing main MBUS communication. At this time, if RS485_rx changes from low level to high level, although NPN triode N3 is completely turned off, third triode capacitor C3 is fully charged, and only resistor R14 and NPN triode N4 are used to discharge, and proper resistor R14 and third triode capacitor C3 are selected, so that third triode capacitor C3 can still maintain voltage around 1V within T (T > 10) seconds, and NPN triode N4 can be completely driven to turn on, so that terminal can always maintain communication in main MBUS.
Referring to fig. 1, when the receiving circuit of the RS485 communication circuit does not receive data, the MBUS and the monitor switching circuit are in a monitor state, monitor communication data of a master-slave machine on the MBUS bus in real time, and send the monitored data to the RS485 bus through the electrically isolated optocoupler and the sending circuit of the RS485 communication circuit.
When the receiving circuit of the RS485 communication circuit receives data, the MBUS and the monitoring switching circuit are in a main MBUS state, the received data are transmitted to the MBUS bus through the electric isolation optocoupler and the voltage transmitting circuit, and the return signal of the MBUS slave is transmitted to the RS485 bus through the electric current receiving circuit through the electric isolation optocoupler and the transmitting circuit of the RS485 communication circuit. Meanwhile, the MBUS and the monitoring switching circuit are kept in a main MBUS state for T seconds, and once the receiving circuit of the RS485 communication circuit receives data, the terminal continues to be kept in the state, the maintenance time is recalculated, and the receiving circuit of the RS485 communication circuit does not receive any signal until the maintenance time exceeds T seconds, and then the terminal is switched to a monitoring mode.
The terminal can be used as master MBUS equipment, and can directly communicate data with slave MBUS equipment through RS 485. The method is applied to occasions with MBUS communication requirements. The MBUS interface may be extended by the device. And the master-slave communication data of the MBUS can be monitored. And the method is compatible with host voltage transmission and slave current transmission, and can master MBUS bus data in real time, thereby providing convenience for on-site troubleshooting and communication data collection. The terminal has simple structure and does not need a specific communication protocol. The level conversion between RS485 and MBUS is only completed, no CPU is needed, programming is not needed, and the anti-interference capability is strong. The CPU main control chip is not needed, the data is transmitted transparently, the communication protocol requirements are not needed, and the use is simple, simple and reliable.
While the preferred embodiment of the present invention has been described in detail, the present invention is not limited to the embodiments, and those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are included in the scope of the present invention as defined in the appended claims.
Claims (8)
1. The communication terminal from TTL to MBUS is characterized by comprising a TTL serial port communication circuit, a voltage transmitting circuit, a current receiving circuit, an MBUS and monitoring switching circuit, an MBUS monitoring circuit and an MBUS interface; the output end of the TTL serial port communication circuit is connected with the input end of the voltage transmitting circuit, the output end of the current receiving circuit and the output end of the MBUS monitoring circuit are connected with the input end of the TTL serial port communication circuit, and the output end of the voltage transmitting circuit, the input end of the current receiving circuit and the MBUS are connected with the monitoring switching circuit; the output end of the MBUS and monitoring switching circuit is connected with the input end of the MBUS monitoring circuit; the MBUS is connected with the monitoring switching circuit and the MBUS interface.
2. The TTL-to-MBUS communication terminal according to claim 1, further comprising an electrical isolation circuit, wherein an output end of the TTL serial port communication circuit is connected to an input end of the voltage transmitting circuit through the electrical isolation circuit, and an output end of the current receiving circuit and an output end of the MBUS monitoring circuit are connected to an input end of the TTL serial port communication circuit through the electrical isolation circuit.
3. The TTL-to-MBUS communication terminal according to claim 2, characterized in that the electrical isolation circuit is an optocoupler.
4. A TTL to MBUS communication terminal according to any one of claims 1 to 3, characterized in that the TTL serial communication circuit is an RS485 communication circuit or an RS232 communication circuit or a USB communication circuit.
5. A TTL to MBUS communication terminal according to any one of claims 1 to 3, characterized in that the voltage transmitting circuit comprises a first NPN transistor, a second NPN transistor and a first PNP transistor; the output end of the TTL serial port communication circuit is connected with the base electrode of a first NPN triode, the emitter electrode of the first NPN triode is connected with the collector electrode of the first PNP triode and the emitter electrode of the second NPN triode, and the emitter electrode of the first NPN triode is grounded; the collector of the first NPN triode is connected with the base of the first PNP triode, the base of the first NPN triode, the emitter of the first PNP triode and the collector of the second NPN triode are connected with a power supply, and the emitter of the second NPN triode and the MBUS are connected with a monitoring switching circuit.
6. The TTL-to-MBUS communication terminal according to any one of claims 1 to 3, characterized in that the current receiving circuit includes a first resistor, a second resistor, a third resistor, a first diode, a first polarity capacitor and a first comparator, the MBUS is connected to the listening switching circuit and one end of the first resistor, the positive electrode of the first diode, the other end of the first resistor is connected to the non-inverting input end of the first comparator, the negative electrode of the first diode is connected to one end of the second resistor, the other end of the second resistor is connected to the inverting input end of the first comparator, one end of the third resistor, the positive electrode of the first polarity capacitor, the ground end of the first comparator, the negative electrode of the first polarity capacitor, the other end of the third resistor are grounded, and the output end of the first comparator is connected to the input end of the TTL serial port communication circuit.
7. A TTL to MBUS communication terminal according to any one of claims 1 to 3, characterized in that the MBUS listening circuit includes a fourth resistor, a fifth resistor, a sixth resistor, a second diode capacitor and a second comparator, the MBUS is connected to the listening switching circuit and one end of the fourth resistor, the positive electrode of the second diode, the other end of the fourth resistor is connected to the non-inverting input end of the second comparator, the negative electrode of the second diode is connected to one end of the fifth resistor, the other end of the fifth resistor is connected to the inverting input end of the second comparator, the positive electrode of the second diode capacitor, one end of the sixth resistor, the ground end of the second comparator, the negative electrode of the second diode capacitor, the other end of the sixth resistor is grounded, and the output end of the second comparator is connected to the input end of the TTL serial communication circuit.
8. The TTL-to-MBUS communication terminal according to any one of claims 1 to 3, characterized in that the MBUS-to-listening switching circuit includes a third NPN triode, a fourth NPN triode, a third triode capacitor and a double pole double throw relay, the TTL serial port communication circuit is connected to a base and a collector of the third NPN triode, a collector of the third NPN triode is connected to a power supply, a collector of the third NPN triode is connected to a base of the fourth NPN triode and a positive electrode of the third triode capacitor, a negative electrode of the third triode capacitor is connected to an emitter of the third NPN triode, the emitter of the third NPN triode is connected to an emitter of the fourth NPN triode, the emitter of the third NPN triode is grounded, the collector of the fourth NPN triode is connected to a first coil connection end of the double pole double throw relay, a second coil connection end of the double pole double throw relay is connected to the power supply, a first normally closed contact of the double throw relay is grounded, and a first normally closed contact of the double pole double throw relay is connected to the first normally closed contact of the double pole relay is grounded; the second normally closed contact of the double-pole double-throw relay is connected with the input end of the MBUS monitoring circuit, the second normally open contact of the double-pole double-throw relay is connected with the output end of the voltage transmitting circuit and the input end of the current receiving circuit, and the second movable contact of the double-pole double-throw relay is connected with the MBUS interface.
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| CN109194322B (en) * | 2018-08-20 | 2023-05-05 | 华立科技股份有限公司 | RS485 high-speed communication capacitive isolation circuit and performance test method thereof |
| CN110519141A (en) * | 2019-08-22 | 2019-11-29 | 深圳龙电电气股份有限公司 | A kind of slave communicating circuit and communication device |
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