CN213906694U - Bus communication circuit and device - Google Patents
Bus communication circuit and device Download PDFInfo
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- CN213906694U CN213906694U CN202023205038.2U CN202023205038U CN213906694U CN 213906694 U CN213906694 U CN 213906694U CN 202023205038 U CN202023205038 U CN 202023205038U CN 213906694 U CN213906694 U CN 213906694U
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Abstract
The utility model discloses a bus communication circuit, which comprises a master station signal sending module, a communication protection module, a signal conversion resistor, a master station signal receiving module and a program-controlled reference voltage adjusting module; the input end of the master station signal transmitting module is connected with the signal transmitting end of the master station, the output end of the master station signal transmitting module is connected with the communication protection module, the program-controlled reference voltage adjusting module and the master station signal receiving module through signal conversion resistors respectively, the program-controlled reference voltage adjusting module is further connected with the master station signal receiving module, and the output end of the master station signal receiving module is connected with the signal receiving end of the master station. The utility model discloses a programme-controlled adjustment reference voltage of algorithm for M-BUS BUS communication circuit can adapt the slave station equipment of more differentiation. The reference voltage in the communication circuit is automatically adjusted through a program control algorithm, and the maximum noise tolerance and the anti-interference capability of the communication circuit can be ensured.
Description
Technical Field
The utility model relates to a circuit electron field especially relates to bus communication circuit and device.
Background
The existing M-BUS communication mode of a remote meter reading system is a master-slave type half-duplex transmission BUS, and double-end communication is realized by adopting a calling/answering mode, namely, after a master station sends out an inquiry, a slave station transmits data to the master station. The master station can send bus voltage to the slave station to supply power to the slave station, and sends logic signals of '1' or '0' to the slave station through voltage amplitude change of the bus voltage to realize data transmission. The slave can then send a "1" or "0" logic signal to the master by adding a pulsed current to the normal slave current. In other words, the master station can supply power to the slave station while sending signals to the slave station through the bus, so that the battery arranged in the terminal instrument of the slave station is only used as a standby power supply, and the working requirements of the slave station for regular maintenance, battery replacement and the like are reduced.
However, in the terminal instruments used in the existing remote meter reading, the pulse currents generated by different instruments are different due to different specification models, and the modules for realizing the pulse current identification in the bus communication cannot accurately identify the logic signals when the pulse currents change. And because the bus length is longer, the noise signal that external environment produced is higher, also is easy to take place data transmission under the influence of noise signal unusually. That is, the conventional bus communication method is low in applicability when it is confronted with noise interference from slave meters of different specifications or different environments.
SUMMERY OF THE UTILITY MODEL
A primary object of the present invention is to provide a bus communication circuit and device, which can solve the problem of insufficient interference rejection and adaptive adjustment capability of the existing bus communication system.
In order to achieve the above object, the present invention provides a bus communication circuit, which includes a master station signal transmitting module, a communication protection module, a signal converting resistor, a master station signal receiving module and a program-controlled reference voltage adjusting module;
the input end of the master station signal sending module is connected with a signal sending end of a master station, the output end of the master station signal sending module is connected with the first end of the communication protection module through the signal conversion resistor, the second end of the communication protection module is connected with a slave station, the first end of the communication protection module is further connected with the first input end of the master station signal receiving module and the input end of the program-controlled reference voltage adjusting module, the output end of the program-controlled reference voltage adjusting module is connected with the second input end of the master station signal receiving module, and the output end of the master station signal receiving module is connected with a signal receiving end of the master station;
the master station signal transmitting module is used for adjusting a first output voltage according to a data signal sent by a master station;
the communication protection module is used for transmitting the first output voltage to the slave station so that the slave station converts the first output voltage to obtain a data signal transmitted by the master station, and is also used for adjusting a first output current according to the data signal transmitted by the slave station;
the signal conversion resistor is used for carrying out voltage reduction adjustment on the first output voltage according to the first output current so as to obtain a first signal voltage or a second signal voltage;
the program-controlled reference voltage adjusting module is used for adjusting the output reference voltage to be between a first signal voltage and a second signal voltage;
and the master station signal receiving module is used for receiving the first signal voltage or the second signal voltage and comparing the first signal voltage or the second signal voltage with a reference voltage to obtain a data signal sent by a slave station and sending the data signal to the master station.
Optionally, the programmable reference voltage adjustment module includes a first diode and a plurality of resistance unit circuits connected in parallel with each other;
the anode of the first diode is connected with the first end of the communication protection module, the cathode of the first diode is respectively connected with the first end of each resistance unit circuit, and the second end of each resistance unit circuit is connected with the second input end of the master station signal receiving module;
the program-controlled reference voltage adjusting module is used for adjusting the equivalent resistance of the program-controlled reference voltage adjusting module by controlling the on-off of the plurality of resistance unit circuits.
Optionally, each of the resistance unit circuits includes an adjusting resistor, a first switching tube, a first resistor, a second resistor, a first capacitor, and a first control unit;
a negative electrode of the first diode is connected with a first end of the first capacitor, a first end of the first resistor and a first end of the first switch tube, a control end of the first switch tube is connected with a second end of the first capacitor, a second end of the first resistor and a first end of the second resistor, a second end of the second resistor is connected with a control end of the first control unit, a controlled end of the first control unit is connected with a master station, and a second end of the first switch tube is connected with a second input end of the master station signal receiving module;
the first control unit is used for controlling the on and off of the first switch tube according to a control signal sent by the main station.
Optionally, the first control unit is a first optocoupler or a second switch tube.
Optionally, the adjustment resistances in each of the resistance unit circuits are different from each other.
Optionally, the master station signal receiving module includes a first comparator, a third resistor, a fourth resistor, a second capacitor, and a second optocoupler;
a first input end of the first comparator is connected with a first end of the communication protection module through the third resistor, a second input end of the first comparator is respectively connected with a second end of each resistor unit circuit, a second end of the first comparator is grounded through a fourth resistor, the second capacitor is connected with the fourth resistor in parallel, an output end of the first comparator is connected with a controlled end of the second optocoupler, and a control end of the second optocoupler is connected with a signal receiving end of the master station;
and the second optical coupler is used for sending corresponding high and low level signals to a signal receiving end of the main station according to the high and low level signals output by the first comparator.
Optionally, the master station signal transmitting module includes a third optocoupler, a voltage stabilizing chip, a first voltage stabilizing diode, and a second voltage stabilizing diode;
the controlled end of the third optical coupler is connected with the signal sending end of the master station, the output anode and the output cathode of the third optical coupler are respectively connected with the cathode and the anode of the second voltage stabilizing diode, the input end of the voltage stabilizing chip is connected with the bus voltage, the grounding end of the voltage stabilizing chip is connected with the cathode of the first voltage stabilizing diode, the anode of the first voltage stabilizing diode is connected with the cathode of the second voltage stabilizing diode, the anode of the second voltage stabilizing diode is grounded, and the output end of the voltage stabilizing chip is the output end of the master station signal sending module.
Optionally, the communication protection module includes a second diode, a transient diode, a third capacitor, and a thermistor;
the anode of the second diode is the first end of the communication protection module, the anode of the second diode is grounded through the third capacitor, the cathode of the second diode is connected with the anode of the slave station through the thermistor, the cathode of the slave station is grounded, and the cathode of the second diode is also grounded through the transient diode.
Optionally, the communication protection module is further configured to receive the first output voltage to supply power to a slave station.
In addition, in order to achieve the above object, the present invention also provides a bus communication device, which includes a master, a slave, and a bus communication circuit connected to the master and the slave, respectively, wherein the bus communication circuit is configured as the bus communication circuit described above.
The utility model discloses a set up programme-controlled reference voltage adjustment module, when the signal interference that causes in the face of different slave station equipment terminals or different external environment, can adjust the reference voltage that master signal receiving module obtained. By adjusting the reference voltage to be at the optimal value between the first signal voltage and the second signal voltage, the bus communication circuit can be adapted to various slave station devices, and the applicability of the bus communication circuit is improved. By adjusting the reference voltage to be close to the optimal value of the first signal voltage and the second signal voltage, the communication circuit can be ensured to obtain the maximum noise tolerance and the maximum interference resistance.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a schematic block diagram of a bus communication circuit according to an embodiment of the present invention;
FIG. 2 is a schematic circuit diagram of the embodiment of FIG. 1;
FIG. 3 is a schematic circuit diagram of an embodiment of a first control unit in the embodiment of FIG. 2;
fig. 4 is a schematic circuit diagram of another embodiment of the first control unit in the embodiment of fig. 2.
The objects, features and advantages of the present invention will be further described with reference to the accompanying drawings.
The reference numbers illustrate:
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.
It should be noted that all the directional indicators (such as upper, lower, left, right, front and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit ly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions in the embodiments may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
The utility model provides a bus communication circuit is applied to bus communication device, and this bus communication device can realize a host computer and a plurality of data communication from between the machine.
Referring to fig. 1, in an embodiment, the bus communication circuit includes a master station signal transmitting module 10, a communication protection module 20, a signal conversion resistor R, a master station signal receiving module 30, and a programmable reference voltage adjusting module 40. The input end of the master station signal transmitting module 10 is connected with the signal transmitting end of the master station, the output end of the master station signal transmitting module 10 is connected with the first end of the communication protection module 20 through a signal conversion resistor R, the second end of the communication protection module 20 is connected with the slave station, the first end of the communication protection module 20 is further connected with the first input end of the master station signal receiving module 30 and the input end of the program-controlled reference voltage adjusting module 40, the output end of the program-controlled reference voltage adjusting module 40 is connected with the second input end of the master station signal receiving module 30, and the output end of the master station signal receiving module 30 is connected with the signal receiving end of the master station.
The master station may transmit a corresponding data signal, for example a logic signal "1" or "0", to an input of the master station signal transmission module 10. The master station signal transmitting module 10 adjusts the output first output voltage accordingly according to the data signal. That is, the first output voltage output by the master station signal transmitting module 10 when receiving the logic signal "1" is different from the first output voltage output when receiving the logic signal "0", and has a larger voltage amplitude difference, so that the back end can recognize two different first output voltages.
The communication protection module 20 may implement receiving and transmitting of data signals, when the communication protection module 20 receives the first output voltage, the first output voltage may be transmitted to the slave station, and the slave station may determine the corresponding data signal according to the voltage amplitude of the first output voltage, so as to implement a data transmission process from the master station to the slave station.
The communication protection module 20 may also receive a data signal from a station and adjust the first output current in accordance with the data signal. The first output voltage is an output voltage of an output end of the master station signal transmitting module 10, and the first output current is a current on a current loop formed by the master station signal transmitting module 10, the signal conversion resistor R, and the communication protection module 20. For example, the data signal transmitted from the slave station may be a logic signal "0" or "1", and the slave station may keep the first output current constant while transmitting the signal "1"; when the signal "0" is transmitted, the consumption of a pulse current is added to the original first output current, and the signal data transmitted from the slave station can be determined by detecting the current amplitude of the first output current.
When the slave station does not generate the pulse current, the amplitude of the voltage reduction of the first output voltage after passing through the signal conversion resistor R is the product of the resistance value of the signal conversion resistor R and the current value of the normal first output current. When the slave station generates the pulse current, the voltage drop on the signal conversion resistor R is increased, and the increased voltage amplitude is the product of the current value of the pulse current and the resistance value of the signal conversion resistor R. That is, when the pulse current is generated in the current loop, the voltage drop generated across the signal conversion resistor R increases, so that the voltage value at the end of the signal conversion resistor R away from the master station signal transmission module 10 is further reduced relative to the voltage value when the pulse current is not generated.
The master station signal receiving module 30 can receive two different first output voltages, namely a first signal voltage and a second signal voltage, which are respectively reduced by the signal conversion resistor R. When the slave station generates a pulse current, the first output voltage is the voltage received by the master station signal receiving module 30 after the voltage drop of the signal conversion resistor R; the second signal voltage is a voltage received by the master station signal receiving module 30 after the first output voltage is dropped by the signal conversion resistor R when the slave station does not generate the pulse current. It can be understood that when a pulse current is generated in the current loop, the voltage drop across the signal conversion resistor R increases, and the voltage of the first signal voltage after passing through the signal conversion resistor R decreases more greatly, i.e. the first signal voltage is lower than the second signal voltage.
The output reference voltage is adjusted by the program-controlled reference voltage adjusting module 40, so that the second signal voltage received by the master station signal receiving module 30 is higher than the reference voltage when no pulse current is generated; when the pulse current is generated, the first signal voltage received by the master station signal receiving module 30 is lower than the reference voltage, that is, the reference voltage is adjusted to be between the first signal voltage and the second signal voltage. The actual signal voltage is compared with the reference voltage, so that the second signal voltage when the actual signal voltage is larger than the reference voltage and the first signal voltage when the actual signal voltage is smaller than the reference voltage can be determined, and whether pulse current is generated in a current loop or not is further determined, and a data signal sent by a slave station is obtained. The master station signal receiving module 30 may send the data signal sent by the slave station to the signal receiving end of the master station after determining the data signal, so as to implement a data transmission process from the slave station to the master station.
It should be noted that, for slave meters with different specifications, the amplitudes of the generated pulse currents are different, so that the voltage amplitude of the stepped-down first output voltage will change, that is, the first signal voltage and the second signal voltage change with the specification change of the slave meters. At this time, if both the first signal voltage and the second signal voltage are greater than or less than the reference voltage, the master station signal receiving module 30 cannot determine whether a pulse current is generated according to the comparison between the signal voltage and the reference voltage, so that the data signal sent by the slave station cannot be determined. And through the program-controlled reference voltage adjusting module 40, when facing different slave station terminal devices, the output reference voltage is adjusted, so that the magnitude of the reference voltage is between the first signal voltage and the second signal voltage, and the slave station can determine to send the data signal through the actual signal voltage. That is, for different slave station device terminals, the reference voltage is tested and adjusted by the program-controlled reference voltage adjusting module 40, and the reference voltages corresponding to the different slave station device terminals can be obtained, so that the bus communication circuit can be adapted to the different slave station devices, and the applicability of the bus communication circuit is improved.
As shown in fig. 1, in the bus communication circuit, the number of the slave stations may be set to one or more, each slave station is connected to one end of a signal conversion resistor R through a communication protection module 20 corresponding to the slave station, and the other end of the signal conversion resistor R is connected to a master station signal transmission module 10.
Similarly, when the reference voltage is set between the first signal voltage and the second signal voltage, if the voltage difference between the reference voltage and the first signal voltage is small, when the voltage of the first signal voltage is increased due to the superposition of the noise signal of the external environment, the first signal voltage on which the interference signal is superposed is easily larger than the reference voltage, thereby affecting the determination of the master station signal receiving module 30 on the data signal. That is, the reference voltage needs to be not only set between the first signal voltage and the second signal voltage, but also have a certain voltage difference with both the first signal voltage and the second signal voltage to provide a noise margin. It can be understood that, by setting the reference voltage as the average value of the first signal voltage and the second signal voltage, the maximum theoretical noise tolerance value, which is half of the difference between the voltages of the first signal voltage and the second signal voltage, can be obtained, thereby improving the interference resistance of the bus communication circuit.
In this embodiment, by providing the programmed reference voltage adjusting module 40, the reference voltage obtained by the master station signal receiving module 30 can be adjusted when signal interference caused by different slave station device terminals or different external environments is faced. By adjusting the reference voltage to be between the first signal voltage and the second signal voltage, the bus communication circuit can be adapted to various slave station devices, and the applicability of the bus communication circuit is improved. By adjusting the reference voltage to be close to the average value of the first signal voltage and the second signal voltage, a larger theoretical noise tolerance value can be obtained, and the anti-interference capability of the bus communication circuit is improved.
Referring to fig. 1 and 2 together, the programmable reference voltage adjustment module 40 may include a first diode D1 and a plurality of resistor unit circuits 41 connected in parallel. An anode of the first diode D1 is connected to the first end of the communication protection module 20, a cathode of the first diode D1 is connected to the first end of each resistor unit circuit 41, and a second end of each resistor unit circuit 41 is connected to the second input end of the master station signal receiving module 30.
The programmable reference voltage adjusting module 40 can control the on/off of the plurality of resistance unit circuits 41 to adjust the equivalent resistance of the programmable reference voltage adjusting module 40. The overall equivalent resistance of the program-controlled reference voltage adjustment module 40 is the resistance value of each turned-on resistance unit circuit 41 after the equivalent resistance is connected in parallel. The second end-to-ground input impedance of the master station signal receiving module 30 and the equivalent resistor of the program-controlled reference voltage adjusting module 40 form a voltage dividing circuit, the equivalent resistor of the program-controlled reference voltage adjusting module 40 is a pull-up resistor, the ground input impedance of the second end of the master station signal receiving module 30 is a pull-down resistor, and the reference voltage obtained by the second end of the master station signal receiving module 30 is a voltage value obtained by dividing the first output voltage by the voltage dividing circuit.
It can be understood that, for the voltage dividing circuit, when the resistance value of the pull-down resistor is not changed, the pull-up resistor is increased, and the divided output voltage is reduced. That is, the reference voltage can be reduced by increasing the overall equivalent resistance of the program-controlled reference voltage adjustment module 40; and the increase of the reference voltage can be realized by reducing the overall equivalent resistance of the program-controlled reference voltage adjusting module 40. The programmable reference voltage adjusting module 40 can generate a plurality of different equivalent resistances by controlling the on/off of the plurality of resistance unit circuits 41. After the generated equivalent resistances are arranged from small to large, the voltage value range of the reference voltage can be determined by testing whether the reference voltage obtained under the condition of each equivalent resistance is between the first signal voltage and the second signal voltage. Taking 3 resistor unit circuits 41 as an example, when the equivalent resistances of the resistor unit circuits 41 are different from each other, a total of 8 combinations exist. By rounding off the equivalent infinite resistances when all of the 3 resistance unit circuits 41 are off, there are 7 equivalent resistance combinations. After the 7 combinations are arranged according to the size sequence, an effective combination can be obtained by traversing and testing each equivalent resistance combination. For example, in the 1 st and 2 nd combinations in which the equivalent resistance is small among the 7 combinations, the generated reference voltage is not located between the first signal voltage and the second signal voltage, and the generated reference voltage in the 3 rd to 7 th combinations is located between the first signal voltage and the second signal voltage. It may be determined that the reference voltage corresponding to the combination 3-7 enables signal data transmission of the slave device terminal. Further, the reference voltage corresponding to the 5 th combination in the 3 rd to 7 th combinations can be selected to be closer to the average value of the first signal voltage and the second signal voltage, so that the master station signal receiving module 30 has a certain noise tolerance capability when comparing the actual signal voltage with the reference voltage.
Each of the resistor unit circuits 41 includes an adjusting resistor Ri, a first switch Q1, a first resistor R1, a second resistor R2, a first capacitor C1, and a first control unit 42. A cathode of the first diode D1 is connected to a first end of the first capacitor C1, a first end of the first resistor R1, and a first end of the first switch Q1, a control end of the first switch Q1 is connected to a second end of the first capacitor C1, a second end of the first resistor R1, and a first end of the second resistor R2, a second end of the second resistor R2 is connected to a control end of the first control unit 42, a controlled end of the first control unit 42 is connected to the master station, and a second end of the first switch Q1 is connected to a second input end of the master station signal receiving module 30.
The master station can control the on/off of each resistance unit circuit 41 by sending control signals. The first switch Q1 may be a PNP transistor or a P-channel MOS transistor, and fig. 2 shows a schematic circuit diagram of the resistor unit circuit 41 when the first switch Q1 is a PNP transistor. The master station may send an on signal or an off signal to the first control unit 42, and when receiving the on signal, the first control unit 42 may ground the control terminal of the first switch Q1 to turn on the first switch Q1; the first control unit 42 may disable the control terminal of the first switch Q1 when receiving the disable signal, so as to disable the first switch Q1. As shown in fig. 2, in the programmable reference voltage adjusting module 40 composed of 3 resistance unit circuits 41, the master station can control the first control unit 42 in each resistance unit circuit 41 through the CTR1, CTR2 and CTR3 ports, respectively.
The first capacitor C1 and the first resistor R1 can prevent the control end of the first switch tube Q1 from shaking due to external signals, and avoid the malfunction of the first switch tube Q1.
It is understood that the first diode D1 is a charging diode, the first capacitor C1 is an energy storage capacitor, and the pulse current is usually 11mA to 20 mA. When no pulse current is generated, the voltage across the first resistor R1 is the second signal voltage, and the first capacitor C1 is charged. When the pulse current is generated to decrease the second signal voltage to the first signal voltage, the first capacitor C1 may keep the voltage across the first resistor R1 at the second signal voltage by discharging. The first resistor R1 and the second resistor R2 form a voltage divider circuit, wherein the resistance of the first resistor R1 is much larger than that of the second resistor R2, so that when the second resistor R2 is grounded, the level of the control end of the first switch tube Q1 is low, and the first switch tube Q1 is turned on. When the second resistor R2 is not grounded, the control terminal of the first switch Q1 is at a high level, and the first switch Q1 is turned off.
It is understood that the signal conversion resistor R may be a winding resistor, and the resistance parameter of the winding resistor may be 100 Ω -3W. The first resistor R1 may be set to be at least ten times larger than the second resistor R2, and the second resistor R2 may be set to be at least 10K Ω, so that the level of the control terminal on the first switch tube Q1 is lower than the conduction level value after the voltage division by the second resistor R2, and the first switch tube Q1 is ensured to be in saturated conduction. The first diode D1 may be a schottky diode with a small reverse current and a low forward conduction voltage drop, such as BAT54 schottky diode with a forward conduction voltage drop of about 0.2V and a reverse leakage current of less than 0.1 μ a. The first switch tube Q1 may be a PNP transistor, such as a germanium tube with a voltage drop of 0.1V-0.2V when the low current is saturated and conducted. The first capacitor C1 in each resistance cell circuit 41 can avoid the influence of the disturbance malfunction. The fourth resistor R4 and the second capacitor C2 in the master station signal receiving module 30, when selected, require a larger time constant τ RC to enable the capacitors to store more energy.
When the first switching tube Q1 is turned on, the resistance unit circuit 41 is turned on. When some of the plurality of resistance cell circuits 41 are in the on state, the overall equivalent resistance of the plurality of resistance cell circuits 41 is a resistance value in which the adjustment resistances Ri of the on resistance cell circuits 41 are connected in parallel with each other.
Note that, in order to obtain different equivalent resistance combinations, the adjustment resistances Ri in the resistance cell circuits 41 may be set to be different from each other. When the number of the resistance unit circuits 41 is n in the case where the resistance values of the adjustment resistors Ri are different from each other, the number of combinations of all the equivalent resistors obtained is 2nThe number of combinations of effective equivalent resistances obtained by removing the infinite equivalent resistances when all the resistance unit circuits 41 are turned off is 2n-1。
It is understood that when the number of the resistance unit circuits 41 is large, 2n1 is larger, miningIt takes a lot of time to measure in a traversal manner whether the reference voltage corresponding to the equivalent resistance of each combination meets the requirement. The efficiency of determining the effective combination can be improved through the segmentation test after determining the equivalent resistance of each combination and arranging the equivalent resistance according to the magnitude sequence. For example, two adjacent equivalent resistance combinations x and y are selected, where the equivalent resistance of x is lower than the equivalent resistance of y. If the reference voltages obtained under the x combination and the y combination are both greater than the first signal voltage and the second signal voltage, the reference voltage is further increased when the equivalent resistance is further decreased. Because the reference voltage under the y combination is higher than the first signal voltage and the second signal voltage, the larger reference voltage does not satisfy the requirement, and other combinations with equivalent resistance smaller than the y combination in the equivalent resistance combination do not need to be tested, so that the testing time is saved, and the testing efficiency is improved.
Referring to fig. 3, when the bus communication circuit has an isolation requirement, the first control unit 42 may be a first optocoupler N1, and when the master station sends a turn-on signal to the first optocoupler N1, the first optocoupler N1 may ground the second end of the second resistor R2; and when the master station sends a cut-off signal to the first optical coupler N1, the first optical coupler N1 can empty the second end of the second resistor R2.
Referring to fig. 4, when the bus communication circuit does not need to isolate the control part from the communication part, the first control unit 42 may be a second switch Q2, and when the master station sends a turn-on signal to the second switch Q2, the second switch Q2 may connect the second terminal of the second resistor R2 to ground; when the master station sends a turn-off signal to the second switch Q2, the second switch Q2 may empty the second terminal of the second resistor R2. The second switch Q2 may be a transistor or a MOS transistor, and fig. 4 only shows a schematic circuit diagram of the first control unit 42 when the second switch is a transistor.
The master station signal receiving module 30 may include a first comparator a1, a third resistor R3, a fourth resistor R4, a second capacitor C2, and a second optocoupler N2. A first input end of the first comparator a1 is connected with a first end of the communication protection module 20 through a third resistor R3, a second input end of the first comparator a1 is connected with a second end of each resistor unit circuit 41, a second end of the first comparator a1 is grounded through a fourth resistor R4, a second capacitor C2 is connected with a fourth resistor R4 in parallel, an output end of the first comparator a1 is connected with a controlled end of a second optocoupler N2, and a control end of the second optocoupler N2 is connected with a signal receiving end of the master station.
The first input terminal of the first comparator a1 may receive the first signal voltage or the second signal voltage, and the second input terminal may receive the reference voltage. After the first end of the first comparator a1 receives the actual signal voltage, the actual signal voltage is determined to be the first signal voltage or the second signal voltage by comparing the actual signal voltage with the reference voltage. When the actual signal voltage is greater than the reference voltage, the actual signal voltage is the second signal voltage; when the actual signal voltage is smaller than the reference voltage, the actual signal voltage is the first signal voltage.
When the first comparator a1 receives the first signal voltage, a low level signal may be output; and when receiving the second signal voltage, a high level signal can be output. When receiving a low-level signal, the second optocoupler N2 may send a corresponding low-level signal to a signal receiving end of the master station; when receiving a high level signal, the second optocoupler N2 may send a corresponding high level signal to a signal receiving end of the master station, and the transmission of the logic signal may be achieved through the high and low level signal.
It can be understood that, in the above embodiment, the second optocoupler N2 can isolate the master station from the bus communication circuit, and the reference voltage and the actual signal voltage at the input end of the first comparator a1 are both voltages of about 30V, and the influence of the higher voltage in the communication part on the low-voltage signal of the master station can be avoided by setting the optocoupler isolation. According to whether the isolation requirement exists, the optical coupling isolation part can be added or cancelled adaptively so as to be suitable for different application scenes. For example, when safety regulation isolation of strong and weak current is required, optical coupling isolation is required. The output terminal of the first comparator a1 is directly connected with the signal receiving terminal of the master station to reduce the cost of the device.
The master station signal transmitting module 10 may include a third optocoupler N3, a voltage regulator chip U1, a first voltage regulator diode ZD1, and a second voltage regulator diode ZD 2. The controlled end of the third optocoupler N3 is connected with the signal sending end of the master station, the output anode and the output cathode of the third optocoupler N3 are respectively connected with the cathode and the anode of the second zener diode ZD2, the input end of the zener chip U1 is connected with the bus voltage, the grounding end of the zener chip U1 is connected with the cathode of the first zener diode ZD1, the anode of the first zener diode ZD1 is connected with the cathode of the second zener diode ZD2, the anode of the second zener diode ZD2 is grounded, and the output end of the zener chip U1 is the output end of the master station signal sending module 10.
When the output anode and the output cathode of the third optocoupler N3 are not conducted, the grounding end of the voltage stabilizing chip U1 is grounded through the two voltage stabilizing diodes. At this time, the ground terminal of the voltage regulation chip U1 is grounded to the ground voltage which is the sum of the breakdown voltages of the two voltage regulation diodes. The signal transmitting end of the master station may transmit a high-low level signal as a logic signal "0" or "1". When the third optical coupler N3 receives a low level signal, the third optical coupler N3 may short-circuit the second zener diode ZD 2. At this time, the ground terminal of the zener chip U1 is grounded to the ground voltage, which is the breakdown voltage of a zener diode. For example, when the breakdown voltages of the two zener diodes are 13V and the bus voltage is 31V, if the third optocoupler N3 receives a high level signal, the output terminal of the zener chip U1 has a voltage of 31V to ground; and if the third optocoupler N3 receives a low level signal, the second zener diode ZD2 is short-circuited, and the voltage of the output terminal of the zener chip U1 to the ground is 18V. The logic signal sent by the signal sending end of the main station can be determined by detecting the output voltage of the voltage stabilizing chip U1, so that the transmission process of the signal is realized.
It can be understood that in fig. 2, the TX end is a signal transmitting end of the master station, and the RX end is a signal receiving end of the master station. The first optical coupler N1 may be a common optical coupler. The second optical coupler N2 and the third optical coupler N3 can be common optical couplers, and high-speed optical couplers can be selected according to the actual communication baud rate.
The communication protection module 20 may include a second diode D2, a transient diode TVS, a third capacitor C3, and a thermistor PTC. The anode of the second diode D2 is the first end of the communication protection module 20, the anode of the second diode D2 is grounded through a third capacitor C3, the cathode of the second diode D2 is connected with the anode of the slave station through a thermistor PTC, the cathode of the slave station is grounded, and the cathode of the second diode D2 is also grounded through a transient diode TVS.
The transient diode TVS can absorb spike pulse signals such as static electricity, lightning strike and the like generated between interfaces of the master station and the slave station to protect a communication circuit. When the current on the current loop is overlarge, the resistance value of the PTC is increased along with the increase of the temperature, and finally the circuit is disconnected so as to protect the power supply of the main station and avoid the damage of the power supply of the main station caused by external short circuit and overload. It will be appreciated that the current loop can be switched on again when the temperature of the thermistor PTC decreases. The third capacitor C3 has a filtering function and can filter the ac interference signal.
It should be noted that, when the slave station receives the first output voltage, the voltage changes with the distance and the bus current, and the slave station may determine the corresponding logic signal "0" or "1" by detecting whether the voltage and the dynamic reference voltage differ by a preset voltage threshold. For example, the slave station may implement dynamic level identification through the interface chip TSS 721A. The dynamic reference voltage of the interface chip is obtained by charging a capacitor in the chip by the voltage received from the station access position, and under the condition that the baud rate is more than 300, a higher output voltage exists in every 11 bits of the transmitted bit stream, so that the dynamic reference voltage can be ensured to be stabilized near the higher output voltage. When the interface chip receives the actual output voltage, whether the difference between the actual output voltage and the dynamic reference voltage exceeds 10V or not is judged, and then the corresponding logic signal '0' or '1' can be determined to be received.
It is understood that, in the above embodiment, the first signal voltage or the second signal voltage transmitted by the master station signal transmitting module 10 is higher than the working voltage of the slave station device, and the quiescent standby current of the slave is the first output current, then the stepped-down first output voltage obtained by the communication protection module 20 may also be used as the working voltage of the slave station to supply power to the slave station after being regulated by the two zener diodes.
As shown in fig. 2, in an embodiment, the calculation formula of the reference voltage received by the second terminal of the first comparator a1 may be:
wherein Umark is the first output voltage, Imark is the first output current, R is the resistance value of the signal conversion resistor R, Ud1 is the conduction voltage drop of the first diode D1, Uq1 is the conduction voltage drop of the first switch tube Q1, Rb is the equivalent dc impedance of the fourth resistor R4, the second capacitor C2 and the equivalent resistance after the ground input impedance of the first comparator a1 are connected in parallel, and the R combination is the equivalent resistance after the adjustment resistors Ri in all the conductive resistance unit circuits 41 are connected in parallel.
The utility model also provides a bus communication device, this bus communication device include the host computer, from the computer and with respectively with the host computer with from the bus communication circuit that the computer is connected, above-mentioned embodiment can be referred to this bus communication circuit's structure, no longer gives unnecessary details here. It should be understood that, since the bus communication device of the present embodiment adopts the technical solution of the bus communication circuit, the bus communication device has all the advantages of the bus communication circuit.
The above is only the optional embodiment of the present invention, and not therefore the scope of the present invention is limited, all the equivalent structures or equivalent flow changes made by the contents of the specification and the drawings, or directly or indirectly applied to other related technical fields, are included in the same way in the protection scope of the present invention.
Claims (10)
1. A bus communication circuit is characterized by comprising a master station signal sending module, a communication protection module, a signal conversion resistor, a master station signal receiving module and a program-controlled reference voltage adjusting module;
the input end of the master station signal sending module is connected with a signal sending end of a master station, the output end of the master station signal sending module is connected with the first end of the communication protection module through the signal conversion resistor, the second end of the communication protection module is connected with a slave station, the first end of the communication protection module is further connected with the first input end of the master station signal receiving module and the input end of the program-controlled reference voltage adjusting module, the output end of the program-controlled reference voltage adjusting module is connected with the second input end of the master station signal receiving module, and the output end of the master station signal receiving module is connected with a signal receiving end of the master station;
the master station signal transmitting module is used for adjusting a first output voltage according to a data signal sent by a master station;
the communication protection module is used for transmitting the first output voltage to the slave station so that the slave station converts the first output voltage to obtain a data signal transmitted by the master station, and is also used for adjusting a first output current according to the data signal transmitted by the slave station;
the signal conversion resistor is used for carrying out voltage reduction adjustment on the first output voltage according to the first output current so as to obtain a first signal voltage or a second signal voltage;
the program-controlled reference voltage adjusting module is used for adjusting the output reference voltage to be between a first signal voltage and a second signal voltage;
and the master station signal receiving module is used for receiving the first signal voltage or the second signal voltage and comparing the first signal voltage or the second signal voltage with a reference voltage to obtain a data signal sent by a slave station and sending the data signal to the master station.
2. The bus communication circuit as claimed in claim 1, wherein the programmable reference voltage adjustment module comprises a first diode and a plurality of resistor unit circuits connected in parallel with each other;
the anode of the first diode is connected with the first end of the communication protection module, the cathode of the first diode is respectively connected with the first end of each resistance unit circuit, and the second end of each resistance unit circuit is connected with the second input end of the master station signal receiving module;
the program-controlled reference voltage adjusting module is used for adjusting the equivalent resistance of the program-controlled reference voltage adjusting module by controlling the on-off of the plurality of resistance unit circuits.
3. The bus communication circuit as claimed in claim 2, wherein each of said resistance unit circuits comprises an adjusting resistor, a first switch tube, a first resistor, a second resistor, a first capacitor and a first control unit;
a negative electrode of the first diode is connected with a first end of the first capacitor, a first end of the first resistor and a first end of the first switch tube, a control end of the first switch tube is connected with a second end of the first capacitor, a second end of the first resistor and a first end of the second resistor, a second end of the second resistor is connected with a control end of the first control unit, a controlled end of the first control unit is connected with a master station, and a second end of the first switch tube is connected with a second input end of the master station signal receiving module;
the first control unit is used for controlling the on and off of the first switch tube according to a control signal sent by the main station.
4. The bus communication circuit as claimed in claim 3, wherein said first control unit is a first optocoupler or a second switch tube.
5. The bus communication circuit as claimed in claim 3, wherein the trimming resistances in each of said resistance cell circuits are different from each other.
6. The bus communication circuit of claim 2, wherein the master station signal receiving module comprises a first comparator, a third resistor, a fourth resistor, a second capacitor, and a second optocoupler;
a first input end of the first comparator is connected with a first end of the communication protection module through the third resistor, a second input end of the first comparator is respectively connected with a second end of each resistor unit circuit, a second end of the first comparator is grounded through a fourth resistor, the second capacitor is connected with the fourth resistor in parallel, an output end of the first comparator is connected with a controlled end of the second optocoupler, and a control end of the second optocoupler is connected with a signal receiving end of the master station;
and the second optical coupler is used for sending corresponding high and low level signals to a signal receiving end of the main station according to the high and low level signals output by the first comparator.
7. The bus communication circuit according to any one of claims 1 to 6, wherein the master station signal transmitting module comprises a third optocoupler, a voltage regulator chip, a first voltage regulator diode and a second voltage regulator diode;
the controlled end of the third optical coupler is connected with the signal sending end of the master station, the output anode and the output cathode of the third optical coupler are respectively connected with the cathode and the anode of the second voltage stabilizing diode, the input end of the voltage stabilizing chip is connected with the bus voltage, the grounding end of the voltage stabilizing chip is connected with the cathode of the first voltage stabilizing diode, the anode of the first voltage stabilizing diode is connected with the cathode of the second voltage stabilizing diode, the anode of the second voltage stabilizing diode is grounded, and the output end of the voltage stabilizing chip is the output end of the master station signal sending module.
8. The bus communication circuit according to any one of claims 1 to 6, wherein the communication protection module comprises a second diode, a transient diode, a third capacitor and a thermistor;
the anode of the second diode is the first end of the communication protection module, the anode of the second diode is grounded through the third capacitor, the cathode of the second diode is connected with the anode of the slave station through the thermistor, the cathode of the slave station is grounded, and the cathode of the second diode is also grounded through the transient diode.
9. The bus communication circuit of claim 8, wherein the communication protection module is further to receive the first output voltage to power a slave station.
10. A bus communication apparatus comprising a master, a slave, and a bus communication circuit connected to the master and the slave, respectively, the bus communication circuit being configured as the bus communication circuit according to any one of claims 1 to 9.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2022134379A1 (en) * | 2020-12-25 | 2022-06-30 | 威胜集团有限公司 | Bus communication circuit and device |
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| WO2022134379A1 (en) * | 2020-12-25 | 2022-06-30 | 威胜集团有限公司 | Bus communication circuit and device |
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