CN209860933U - Multi-node control circuit based on 485 communication - Google Patents
Multi-node control circuit based on 485 communication Download PDFInfo
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- CN209860933U CN209860933U CN201921114577.XU CN201921114577U CN209860933U CN 209860933 U CN209860933 U CN 209860933U CN 201921114577 U CN201921114577 U CN 201921114577U CN 209860933 U CN209860933 U CN 209860933U
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Abstract
The utility model discloses a multinode control circuit based on 485 communications, follow RS485 interface module including a main RS485 interface module and a plurality of, main RS485 interface module is connected with first follow RS485 interface module through the shielding paired line, first follow RS485 interface module through shielding paired line and second follow RS485 interface module, analogize in proper order, the n-1 follows RS485 interface module shielding paired line and the n is connected from RS485 interface module. When the power supply module in the slave RS485 interface module is damaged, the slave RS485 interface module directly connects the incoming line end with the emergence end through switching of the relay contact, so that the slave RS485 interface module is separated from the communication bus, and at the moment, the signal received by the RS485 interface module with the damaged power supply module is not processed by the RS485 interface circuit in the slave RS485 interface module.
Description
Technical Field
The utility model relates to a serial ports communication circuit technical field especially relates to a multinode control circuit based on 485 communications.
Background
The RS-485 serial bus adopts balanced transmission and differential reception, so that the RS-485 serial bus has the capability of inhibiting common-mode interference, and the RS-485 serial bus is widely adopted when the communication distance is required to be dozens of meters to thousands of meters. A master-slave communication mode is generally adopted in the RS485 communication network, that is, one master has a plurality of slaves, and the topology structure is as shown in fig. 1. When the RS485 interface is used, for a specific transmission line, the maximum cable length allowed by data signal transmission from the RS485 interface to a load is inversely proportional to the baud rate of the signal transmission, and the length data is mainly affected by factors such as signal distortion and noise. Theoretically, when the communication rate is 100Kbps or less, the longest transmission distance of the RS485 can reach 1200 meters, but the transmission distance in practical applications is different due to the transmission characteristics of the chip and the cable. In addition, when a node fails in the existing topology, the communication bus is greatly affected.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem how to provide a not only can prolong total transmission distance, when can preventing certain node from breaking down again, cause the multinode control circuit of the 485 communications of influence to the communication bus.
In order to solve the technical problem, the utility model discloses the technical scheme who takes is: the utility model provides a multinode control circuit based on 485 communication which characterized in that: the RS485 interface module comprises a master RS485 interface module and a plurality of slave RS485 interface modules, wherein the master RS485 interface module is connected with a first slave RS485 interface module through a shielding twisted pair, the first slave RS485 interface module is connected with a second slave RS485 interface module through a shielding twisted pair, the analogy is carried out in sequence, an n-1 th slave RS485 interface module shields the twisted pair and is connected with an nth slave RS485 interface module, n is a natural number larger than 2, and when the slave RS485 interface module is normal, the slave RS485 interface module communicates with the adjacent slave RS485 interface module through an RS485 interface circuit in the module.
The further technical scheme is as follows: the main RS485 interface module and the slave RS485 interface module comprise two power supply modules, two relays, two 485 chips and an optical coupling chip, and the power supply modules respectively provide working power supplies for the relays, the 485 chips and the optical coupling chip; two terminals of a signal input wire inlet end P1 are respectively connected with an input differential signal A, B, two terminals of P1 are respectively connected with a common end of a double-pole double-throw switch in a relay K1, and two normally closed contact terminals of the double-pole double-throw switch in the relay K1 are respectively connected with two normally closed contact terminals of the double-pole double-throw switch in a relay K2; the two normally open contact terminals of a double-pole double-throw switch in the relay K1 are divided into three paths respectively, wherein the first path of one normally open contact terminal is connected with a pin 6 of a MAX485SEA type chip U2, the second path is grounded through a voltage stabilizing diode D1, the third path is connected with a +5V power supply through a resistor R3, the first path of the other normally open contact terminal is connected with a pin 7 of a MAX485SEA type chip U2, the second path is grounded through a voltage stabilizing diode D2, and the third path is grounded through a resistor R5; the U2 only operates in a receive mode; the 8 pins of the U2 are divided into two paths, the first path is connected with a +5V power supply, and the second path is grounded through a capacitor C1; pins 2, 3 and 5 of the U2 are grounded; 4 feet of the U2 are suspended; the 1 pin of the U2 is divided into three paths, the first path is connected with the cathode of a light emitting diode in an optocoupler U3, the second path is connected with a +5V power supply through a resistor R2, and the third path is connected with the 4 pin of a MAX485SEA type chip U4; two terminals of a signal output terminal P5 are differential signal output terminals, two differential signal output terminals of the P5 are respectively connected with a common end of a double-pole double-throw switch in a relay K2, two normally open contact terminals of the double-pole double-throw switch in the relay K2 are respectively divided into three paths, a first path of one normally open contact terminal is connected with a pin 6 of a MAX485SEA type chip U4, a second path of the normally open contact terminal is grounded through a voltage stabilizing diode D3, a third path of the normally open contact terminal is connected with a +5V power supply through a resistor R6, a first path of the other normally open contact terminal is connected with a pin 7 of a MAX485SEA type chip U4, a second path of the normally open contact terminal is grounded through a voltage stabilizing diode D4; the U4 only operates in a transmit mode; the 8 pins of the U4 are divided into two paths, the first path is connected with a +5V power supply, and the second path is grounded through a capacitor C3; the pins 2 and 3 of the U4 are connected with a +5V power supply; the 1 pin of the U4 is suspended, and the 5 pin of the U4 is grounded;
the positive pole of a light emitting diode in the optocoupler U3 is connected with a +5V power supply through a resistor R4, the emitting electrode of a phototriode in the optocoupler U3 is grounded, the collecting electrode of the phototriode in the optocoupler U3 is divided into two paths, the first path is the signal output end of the RS485 interface module and provides TTL level signals for a microprocessor, and the second path is connected with the +5V power supply through a resistor R1.
The further technical scheme is as follows: the first power supply module comprises an AC/DC conversion chip P2, the input end of the P2 is connected with an alternating current 220V power supply, the positive output end of the AC/DC conversion chip P2 is divided into three paths after passing through an inductor L1, the first path is the +5V power supply output end of the first power supply module, the second path is grounded through a capacitor C4, and the third path is grounded through a capacitor C6.
The further technical scheme is as follows: the second power supply module comprises an AC/DC conversion chip P3, the input end of the P3 is connected with an alternating current 220V power supply, the positive output end of the AC/DC conversion chip P3 is divided into three paths after passing through an inductor L2, the first path is the +5V power supply output end of the second power supply module, the second path is grounded through a capacitor C5, and the third path is grounded through a capacitor C7.
The further technical scheme is as follows: and a signal output end in the slave RS485 interface module, which is connected with the optical coupler, is connected with a TTL level serial port input end of a singlechip U1.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: this application among the control circuit, when the node appear thunderbolt or other reasons cause power module P3 trouble not have the output, relay K1, K2 coil lose electricity, and its normally closed contact is closed, and normally open contact is opened, and the RS485 differential signal with wiring end P1 input is direct through wiring end P5 output, falls this node bypass from communication bus, can guarantee that communication bus reliably connects. After the RS485 differential signal is converted by the control circuit through U2 (receiving) and U4 (sending), the longest transmission distance of the RS485 can be theoretically achieved by the effective transmission distance between every two communication nodes, the number of the communication nodes is not limited, and therefore the total communication distance can not be limited.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
FIG. 1 is a prior art diagram of an RS485 serial bus topology;
fig. 2 is a topology structure diagram of relay communication in the embodiment of the present invention;
fig. 3 is a schematic circuit diagram of an RS485 interface module (communication node) in the embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the 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 work belong to the protection scope of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be implemented in other ways different from the specific details set forth herein, and one skilled in the art may similarly generalize the present invention without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
As shown in fig. 2, the embodiment of the utility model discloses a multinode control circuit based on 485 communication, including a main RS485 interface module and a plurality of follow RS485 interface module, main RS485 interface module is connected with first follow RS485 interface module through the shielding twisted pair, first follow RS485 interface module is through shielding twisted pair and second follow RS485 interface module, analogize in proper order, the n-1 follows RS485 interface module shielding twisted pair and the nth follows RS485 interface module and is connected, and n is for being greater than 2 natural number, and when normal, follow RS485 interface module and pass through the RS485 interface circuit in the module and adjacent communicate from RS485 interface module; when the power supply module in the slave RS485 interface module is damaged, the slave RS485 interface module directly connects the incoming line end with the emergence end through switching of the relay contact, so that the slave RS485 interface module is separated from the communication bus, and at the moment, the signal received by the RS485 interface module with the damaged power supply module is not processed by the RS485 interface circuit in the slave RS485 interface module.
Further, as shown in fig. 3, the master RS485 interface module and the slave RS485 interface module include two power modules, two relays, two 485 chips, and an optocoupler chip, and the power modules respectively provide working power supplies for the relays, the 485 chips, and the optocoupler chip; two terminals of a signal input wire inlet end P1 are respectively connected with an input differential signal A, B, two terminals of P1 are respectively connected with a common end of a double-pole double-throw switch in a relay K1, and two normally closed contact terminals of the double-pole double-throw switch in the relay K1 are respectively connected with two normally closed contact terminals of the double-pole double-throw switch in a relay K2; the two normally open contact terminals of a double-pole double-throw switch in the relay K1 are divided into three paths respectively, wherein the first path of one normally open contact terminal is connected with a pin 6 of a MAX485SEA type chip U2, the second path is grounded through a voltage stabilizing diode D1, the third path is connected with a +5V power supply through a resistor R3, the first path of the other normally open contact terminal is connected with a pin 7 of a MAX485SEA type chip U2, the second path is grounded through a voltage stabilizing diode D2, and the third path is grounded through a resistor R5; the U2 only operates in a receive mode; the 8 pins of the U2 are divided into two paths, the first path is connected with a +5V power supply, and the second path is grounded through a capacitor C1; pins 2, 3 and 5 of the U2 are grounded; 4 feet of the U2 are suspended; the 1 pin of the U2 is divided into three paths, the first path is connected with the cathode of a light emitting diode in an optocoupler U3, the second path is connected with a +5V power supply through a resistor R2, and the third path is connected with the 4 pin of a MAX485SEA type chip U4; two terminals of a signal output terminal P5 are differential signal output terminals, two differential signal output terminals of the P5 are respectively connected with a common end of a double-pole double-throw switch in a relay K2, two normally open contact terminals of the double-pole double-throw switch in the relay K2 are respectively divided into three paths, a first path of one normally open contact terminal is connected with a pin 6 of a MAX485SEA type chip U4, a second path of the normally open contact terminal is grounded through a voltage stabilizing diode D3, a third path of the normally open contact terminal is connected with a +5V power supply through a resistor R6, a first path of the other normally open contact terminal is connected with a pin 7 of a MAX485SEA type chip U4, a second path of the normally open contact terminal is grounded through a voltage stabilizing diode D4; the U4 only operates in a transmit mode; the 8 pins of the U4 are divided into two paths, the first path is connected with a +5V power supply, and the second path is grounded through a capacitor C3; the pins 2 and 3 of the U4 are connected with a +5V power supply; the 1 pin of the U4 is suspended, and the 5 pin of the U4 is grounded;
the positive pole of a light emitting diode in the optocoupler U3 is connected with a +5V power supply through a resistor R4, the emitting electrode of a phototriode in the optocoupler U3 is grounded, the collecting electrode of the phototriode in the optocoupler U3 is divided into two paths, the first path is the signal output end of the RS485 interface module and provides TTL level signals for a microprocessor, and the second path is connected with the +5V power supply through a resistor R1.
Further, as shown in fig. 3, the first power module includes an AC/DC conversion chip P2, an input terminal of the P2 is connected to an AC 220V power supply, a positive output terminal of the AC/DC conversion chip P2 is divided into three paths after passing through an inductor L1, the first path is a +5V power output terminal of the first power module, the second path is grounded through a capacitor C4, and the third path is grounded through a capacitor C6.
Further, as shown in fig. 3, the second power module includes an AC/DC conversion chip P3, an input terminal of the P3 is connected to an AC 220V power supply, a positive output terminal of the AC/DC conversion chip P3 is divided into three paths after passing through an inductor L2, the first path is a +5V power output terminal of the second power module, the second path is grounded through a capacitor C5, and the third path is grounded through a capacitor C7.
In fig. 3, P2 and P3 are power modules, which convert the input ac 220V voltage into a stable dc 5V voltage; u1 is a single chip with serial port; u3 is an optical coupler and plays a role in signal isolation; u2 and U4 are MAX485 chips, U2 works in a receiving mode only, and U4 works in a sending mode only; k1 and K2 are relays for switching signals; p1 is RS485 signal input terminal, P5 is RS485 signal output terminal.
When the power is normally supplied, the coils of the relays K1 and K2 are electrified, the normally open contacts are closed, the P1 terminal is communicated with the U2, and the P5 terminal is communicated with the U4 (double-pole double-throw switches in K1 and K2 respectively communicate the upper contacts with the U2 and the U4 in the figure 3). An RS485 differential signal input by P1 is converted into a TTL level signal through U2, and the level signal is input to a serial port receiving end of a singlechip U1 through an optical coupler and used for data processing; the TTL level signal converted by the U2 is simultaneously input to a TTL level receiving end of the U4, and the TTL level signal is converted into an RS485 differential signal by the U4 and is output through a P5 terminal.
When no output occurs in the power module P3 due to lightning strike or other reasons, the coils of the relays K1 and K2 lose power, the normally closed contacts are closed, the normally open contacts are opened, an RS485 differential signal input by the P1 terminal is directly output through the P5 terminal, the node is bypassed from the communication bus, and meanwhile, the reliable connection of the communication bus is ensured.
According to the design, after the RS485 differential signal is converted through U2 (receiving) and U4 (sending), the longest transmission distance of the RS485 can be theoretically achieved through the effective transmission distance between every two communication nodes, the number of the communication nodes is not limited, and therefore the total communication distance can not be limited.
Claims (5)
1. The utility model provides a multinode control circuit based on 485 communication which characterized in that: the RS485 interface module comprises a master RS485 interface module and a plurality of slave RS485 interface modules, wherein the master RS485 interface module is connected with a first slave RS485 interface module through a shielding twisted pair, the first slave RS485 interface module is connected with a second slave RS485 interface module through a shielding twisted pair, the analogy is carried out in sequence, an n-1 th slave RS485 interface module shields the twisted pair and is connected with an nth slave RS485 interface module, n is a natural number larger than 2, and when the slave RS485 interface module is normal, the slave RS485 interface module communicates with the adjacent slave RS485 interface module through an RS485 interface circuit in the module.
2. The 485-communication-based multi-node control circuit of claim 1, wherein: the main RS485 interface module and the slave RS485 interface module comprise two power supply modules, two relays, two 485 chips and an optical coupling chip, and the power supply modules respectively provide working power supplies for the relays, the 485 chips and the optical coupling chip; two terminals of a signal input wire inlet end P1 are respectively connected with an input differential signal A, B, two terminals of P1 are respectively connected with a common end of a double-pole double-throw switch in a relay K1, and two normally closed contact terminals of the double-pole double-throw switch in the relay K1 are respectively connected with two normally closed contact terminals of the double-pole double-throw switch in a relay K2; the two normally open contact terminals of a double-pole double-throw switch in the relay K1 are divided into three paths respectively, wherein the first path of one normally open contact terminal is connected with a pin 6 of a MAX485SEA type chip U2, the second path is grounded through a voltage stabilizing diode D1, the third path is connected with a +5V power supply through a resistor R3, the first path of the other normally open contact terminal is connected with a pin 7 of a MAX485SEA type chip U2, the second path is grounded through a voltage stabilizing diode D2, and the third path is grounded through a resistor R5; the U2 only operates in a receive mode; the 8 pins of the U2 are divided into two paths, the first path is connected with a +5V power supply, and the second path is grounded through a capacitor C1; pins 2, 3 and 5 of the U2 are grounded; 4 feet of the U2 are suspended; the device comprises a U2, a relay K2, a MAX485SEA type chip U4, a relay K2, a MAX485SEA type chip U4, a resistor R2, a resistor R6323 and a resistor D6324, wherein 1 pin of the U2 is divided into three paths, the first path is connected with the cathode of a light emitting diode in the optocoupler U3, the second path is connected with a +5V power supply through the resistor R2, and the third path is connected with a 4 pin of the MAX485SEA type chip U4; the U4 only operates in a transmit mode; the 8 pins of the U4 are divided into two paths, the first path is connected with a +5V power supply, and the second path is grounded through a capacitor C3; the pins 2 and 3 of the U4 are connected with a +5V power supply; the 1 pin of the U4 is suspended, and the 5 pin of the U4 is grounded;
the positive pole of a light emitting diode in the optocoupler U3 is connected with a +5V power supply through a resistor R4, the emitting electrode of a phototriode in the optocoupler U3 is grounded, the collecting electrode of the phototriode in the optocoupler U3 is divided into two paths, the first path is the signal output end of the RS485 interface module and provides TTL level signals for a microprocessor, and the second path is connected with the +5V power supply through a resistor R1.
3. The 485-communication-based multi-node control circuit of claim 2, wherein: the first power supply module comprises an AC/DC conversion chip P2, the input end of the P2 is connected with an alternating current 220V power supply, the positive output end of the AC/DC conversion chip P2 is divided into three paths after passing through an inductor L1, the first path is the +5V power supply output end of the first power supply module, the second path is grounded through a capacitor C4, and the third path is grounded through a capacitor C6.
4. The 485-communication-based multi-node control circuit of claim 2, wherein: the second power supply module comprises an AC/DC conversion chip P3, the input end of the P3 is connected with an alternating current 220V power supply, the positive output end of the AC/DC conversion chip P3 is divided into three paths after passing through an inductor L2, the first path is the +5V power supply output end of the second power supply module, the second path is grounded through a capacitor C5, and the third path is grounded through a capacitor C7.
5. The 485-communication-based multi-node control circuit of claim 2, wherein: and a signal output end in the slave RS485 interface module, which is connected with the optical coupler, is connected with a TTL level serial port input end of a singlechip U1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921114577.XU CN209860933U (en) | 2019-07-16 | 2019-07-16 | Multi-node control circuit based on 485 communication |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921114577.XU CN209860933U (en) | 2019-07-16 | 2019-07-16 | Multi-node control circuit based on 485 communication |
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| Publication Number | Publication Date |
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| CN209860933U true CN209860933U (en) | 2019-12-27 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201921114577.XU Active CN209860933U (en) | 2019-07-16 | 2019-07-16 | Multi-node control circuit based on 485 communication |
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| CN (1) | CN209860933U (en) |
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- 2019-07-16 CN CN201921114577.XU patent/CN209860933U/en active Active
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