CN109088753B - Circuit and method for automatically detecting RS485 communication fault - Google Patents
Circuit and method for automatically detecting RS485 communication fault Download PDFInfo
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- CN109088753B CN109088753B CN201810840495.7A CN201810840495A CN109088753B CN 109088753 B CN109088753 B CN 109088753B CN 201810840495 A CN201810840495 A CN 201810840495A CN 109088753 B CN109088753 B CN 109088753B
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Abstract
The invention provides a circuit for automatically detecting RS485 communication faults, which comprises a master device and a slave device, wherein the master device comprises a first detection circuit, a second detection circuit and a first detection circuit; the circuit of the master device comprises a first microprocessor, a first RS485 transceiver circuit and a second RS485 transceiver circuit; the first RS485 receiving and transmitting circuit is connected with the first microprocessor and is provided with external RS485 communication ports A1 and B1; the second RS485 receiving and transmitting circuit is connected with the first microprocessor and is provided with external RS485 communication ports A2 and B2; two external RS485 communication ports A1 and B1, A2 and B2 of the main equipment have independent data transceiving functions; the circuit of the slave device comprises a second microprocessor, a third RS485 receiving and transmitting circuit, an RS485 receiving circuit and a switching circuit; the external RS485 communication ports A3 and B3 of the third RS485 transceiver circuit are connected with the switching circuit; the external RS485 communication ports A4 and B4 of the RS485 receiving circuit are connected with the switching circuit; the second microprocessor controls the switching circuit; the invention can detect the fault in the RS485 circuit of the access control system in a short time.
Description
Technical Field
The invention relates to the technical field of RS485 bus communication, in particular to a method for detecting RS485 communication faults.
Background
An RS485 bus is adopted between a network controller and a local controller in an access control system for networking, and the communication problem of the whole RS485 network can be caused by the line hardware faults (disconnection, poor contact and the like) of the RS485 bus and the software faults (receiving buffer overflow, protocol data error and the like) of the controller in actual use. The problem needs to be positioned and solved in time in the use of the access control system so as to ensure the stable operation of the whole system. In general, communication problems need to be checked one by one in a manual field, much time is needed, and the problems are difficult to be positioned and solved at the first time.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a circuit for automatically detecting an RS485 communication fault and a method for automatically detecting the RS485 communication fault so as to solve the problem that the communication fault in a short time in an access control system is difficult to locate. The technical scheme adopted by the invention is as follows:
a circuit for automatically detecting RS485 communication faults comprises a master device and a slave device; the method is characterized in that:
the circuit of the master device comprises a first microprocessor and at least one RS485 transceiver circuit; the RS485 receiving and transmitting circuit of the main equipment is connected with the first microprocessor and is provided with an external RS485 communication port; the external RS485 communication port of the main equipment has the data receiving and transmitting function;
the circuit of the slave device comprises a second microprocessor, a third RS485 receiving and transmitting circuit, an RS485 receiving circuit and a switching circuit; the third RS485 receiving and transmitting circuit is connected with the second microprocessor, the second microprocessor controls data receiving and transmitting of the third RS485 receiving and transmitting circuit, and external RS485 communication ports A3 and B3 of the third RS485 receiving and transmitting circuit are connected with the switching circuit; the external RS485 communication ports A3 and B3 of the third RS485 transceiver circuit have a data transceiving function;
the RS485 receiving circuit is connected with the second microprocessor, and the second microprocessor receives data of the RS485 receiving circuit; the external RS485 communication ports A4 and B4 of the RS485 receiving circuit are connected with the switching circuit; the RS485 receiving circuit has the functions of receiving data of external RS485 communication ports A4 and B4 and sending the data to the second microprocessor;
the switching circuit is connected with the second microprocessor, the second microprocessor controls the switching circuit, and external communication ports A5 and B5 of the switching circuit are selected to be connected into the third RS485 transceiver circuit or the RS485 receiver circuit, so that the slave equipment is in different running states;
the RS485 communication port of the master device outside is connected with the RS485 bus, and the external communication ports A5 and B5 of each slave device are sequentially connected to the RS485 bus.
Preferably, the circuit of the master device comprises a first RS485 transceiver circuit and a second RS485 transceiver circuit; the first RS485 receiving and transmitting circuit is connected with the first microprocessor and is provided with external RS485 communication ports A1 and B1; the second RS485 receiving and transmitting circuit is connected with the first microprocessor and is provided with external RS485 communication ports A2 and B2; two external RS485 communication ports A1 and B1, A2 and B2 of the main equipment have independent data transceiving functions;
two sets of RS485 communication ports A1 and B1, A2 and B2 which are arranged outside the main equipment are connected into an annular RS485 bus; the outward communication ports A5 and B5 of the slave devices are sequentially connected to the ring-shaped RS485 bus.
Further, the second microprocessor of the slave device is also connected with a storage unit for storing the software fault in the RS485 communication.
Further, when the switching circuit selects the external RS485 communication ports A3, B3 of the third RS485 transceiver circuit to connect with the external communication ports a5, B5 of the switching circuit, the slave device is in the "communication state", and when the switching circuit selects the external RS485 communication ports a4, B4 of the RS485 receiver circuit to connect with the external communication ports a5, B5 of the switching circuit, the slave device is in the "detection state", and the slave device is in the "detection state" by default; when the slave device in the detection state receives the data packet P2, the slave device is switched to the communication state, and uploads the data packet P3 through the external RS485 communication ports A3 and B3 of the third RS485 transceiver circuit; when the slave device in the "communication state" receives the packet P4, the packet P5 is uploaded; each time the slave device is switched from the communication state to the detection state, the system initialization operation is carried out; when the slave device is in the "communication state", it automatically switches to the "detection state" when a specific packet is not received within the period T.
Further, the data packet P5 contains a software failure in RS485 communication.
Further, the specific packet is referred to as a packet P4.
A method for automatically detecting RS485 communication faults comprises the following steps:
step S1, the master device stops sending data, waits for N seconds, N > T, all the slave devices are switched to a detection state, and the slave devices perform system initialization operation;
step S2, the master device sends a packet P2 to the first slave device, and the first slave device switches to "communication state" after receiving the packet P2, and uploads a packet P3 through the external communication ports a5 and B5;
step S3, if the master device does not receive the data packet P3, recording that a hardware fault point exists between the master device and the first slave device, ending fault detection, and updating a fault code table;
if the master device receives the data packet P3, the master device continues to send the data packet P4, and uploads the data packet P5 after receiving the data packet P4 from the first slave device; the data packet P5 contains software failure in RS485 communication read from the storage unit;
after receiving the data packet P5, the master device analyzes the data packet P5 to determine a software fault and updates a fault code table;
step S4, completing the detection of the first slave device, and detecting the next slave device according to the steps S1-S3;
in the above process, when the switching circuit selects the external RS485 communication ports A3, B3 of the third RS485 transceiver circuit to connect with the external communication ports a5, B5 of the switching circuit, the slave device is in the "communication state", and when the switching circuit selects the external RS485 communication ports a4, B4 of the RS485 receiver circuit to connect with the external communication ports a5, B5 of the switching circuit, the slave device is in the "detection state", and the slave device is in the "detection state" by default; when the slave device is in the "communication state", it automatically switches to the "detection state" when a specific packet is not received within the period T.
The invention has the advantages that: the circuit and the method provided by the invention can detect software faults and hardware faults in the RS485 circuit of the access control system in a short time, solve the communication faults of the RS485 circuit in time and ensure the normal operation of data communication of the access control system.
Drawings
Fig. 1 is an electrical schematic diagram of the master device of the present invention.
Fig. 2 is an electrical schematic diagram of the slave device of the present invention.
Fig. 3 is a network diagram of RS485 communication equipment of the access control system of the present invention.
Fig. 4 is a flow chart of the automatic fault detection of the present invention.
Detailed Description
The invention is further illustrated by the following specific figures and examples.
The circuit for automatically detecting the RS485 communication fault comprises a main device and a slave device;
the circuit of the master device is shown in fig. 1 and comprises a first microprocessor, a first RS485 transceiver circuit and a second RS485 transceiver circuit; the first RS485 receiving and transmitting circuit is connected with the first microprocessor and is provided with external RS485 communication ports A1 and B1; the second RS485 receiving and transmitting circuit is connected with the first microprocessor and is provided with external RS485 communication ports A2 and B2; two external RS485 communication ports A1 and B1, A2 and B2 of the main equipment have independent data transceiving functions;
the circuit of the slave device is shown in fig. 2 and comprises a second microprocessor, a third RS485 transceiver circuit, an RS485 receiver circuit and a switching circuit; the third RS485 receiving and transmitting circuit is connected with the second microprocessor, the second microprocessor controls data receiving and transmitting of the third RS485 receiving and transmitting circuit, and external RS485 communication ports A3 and B3 of the third RS485 receiving and transmitting circuit are connected with the switching circuit; the external RS485 communication ports A3 and B3 of the third RS485 transceiver circuit have a data transceiving function;
the RS485 receiving circuit is connected with the second microprocessor, and the second microprocessor only receives data of the RS485 receiving circuit; the external RS485 communication ports A4 and B4 of the RS485 receiving circuit are connected with the switching circuit; the RS485 receiving circuit only has the functions of receiving the data of the external RS485 communication ports A4 and B4 and sending the data to the second microprocessor;
the switching circuit is connected with the second microprocessor, the second microprocessor controls the switching circuit, and external communication ports A5 and B5 of the switching circuit are selected to be connected into the third RS485 transceiver circuit or the RS485 receiver circuit, so that the slave equipment is in different running states;
when the switching circuit selects the external RS485 communication ports A3 and B3 of the third RS485 transceiver circuit to be connected with the external communication ports A5 and B5 of the switching circuit, the slave device is in a communication state, and when the switching circuit selects the external RS485 communication ports A4 and B4 of the RS485 receiving circuit to be connected with the external communication ports A5 and B5 of the switching circuit, the slave device is in a detection state, and the slave device is in the detection state by default; when the slave device in the detection state receives the data packet P2, the slave device is switched to the communication state, and uploads the data packet P3 through the external RS485 communication ports A3 and B3 of the third RS485 transceiver circuit; when the slave device in the "communication state" receives the packet P4, the packet P5 is uploaded; the slave equipment is switched from the communication state to the detection state every time, system initialization operation is carried out, and RS485 communication faults caused by software faults are solved; when the slave device is in a communication state, when a specific data packet (P4 data packet) is not received in a period T, the slave device is automatically switched to a detection state;
the second microprocessor of the slave device is connected with a storage unit, such as FLASH, and is used for storing software faults in RS485 communication;
the RS485 communication circuit of the access control system is generally composed of a master device and 16 slave devices, as shown in fig. 3; two sets of RS485 communication ports A1 and B1, A2 and B2 which are arranged outside the main equipment are connected into an annular RS485 bus; the external communication ports A5 and B5 of each slave device are sequentially connected to the annular RS485 bus; the connection mode is a better connection mode, and when one group of the external RS485 communication ports on the main equipment fails, the other group of the external RS485 communication ports can still work;
in another embodiment, only one RS485 transceiver circuit may be provided in the master device, an RS485 bus is connected to an external RS485 communication port of the master device (that is, an external RS485 communication port of the RS485 transceiver circuit), and the external communication ports a5 and B5 of the slave devices are sequentially connected to the RS485 bus. This connection is simple but lacks redundancy.
The method for automatically detecting the RS485 communication fault is shown in FIG. 4, and comprises the following steps:
step S1, the master device stops sending data, waits for N seconds, N > T, all the slave devices are switched to a detection state, and the slave devices perform system initialization operation;
step S2, the master device sends a packet P2 to the first slave device, and the first slave device switches to "communication state" after receiving the packet P2, and uploads a packet P3 through the external communication ports a5 and B5;
step S3, if the master device does not receive the data packet P3, recording that a hardware fault point exists between the master device and the first slave device, ending fault detection, and updating a fault code table;
if the master device receives the data packet P3, the master device continues to send the data packet P4, and uploads the data packet P5 after receiving the data packet P4 from the first slave device; the data packet P5 contains software failure in RS485 communication read from the storage unit;
after receiving the data packet P5, the master device analyzes the data packet P5 to determine a software fault and updates a fault code table;
in step S4, the first slave device is detected, and the next slave device is detected in steps S1 to S3.
The method can timely record common software and hardware faults in the RS485 communication network of the access control system into the fault code table, inform maintenance personnel to timely solve the communication faults of the RS485, and ensure the stable operation of the access control system.
Finally, it should be noted that the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to examples, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (1)
1. A circuit for automatically detecting RS485 communication faults comprises a master device and a slave device; the method is characterized in that:
the circuit of the master device comprises a first microprocessor and at least one RS485 transceiver circuit; the RS485 receiving and transmitting circuit of the main equipment is connected with the first microprocessor and is provided with an external RS485 communication port; the external RS485 communication port of the main equipment has the data receiving and transmitting function;
the circuit of the slave device comprises a second microprocessor, a third RS485 receiving and transmitting circuit, an RS485 receiving circuit and a switching circuit; the third RS485 receiving and transmitting circuit is connected with the second microprocessor, the second microprocessor controls data receiving and transmitting of the third RS485 receiving and transmitting circuit, and external RS485 communication ports A3 and B3 of the third RS485 receiving and transmitting circuit are connected with the switching circuit; the external RS485 communication ports A3 and B3 of the third RS485 transceiver circuit have a data transceiving function;
the RS485 receiving circuit is connected with the second microprocessor, and the second microprocessor receives data of the RS485 receiving circuit; the external RS485 communication ports A4 and B4 of the RS485 receiving circuit are connected with the switching circuit; the RS485 receiving circuit has the functions of receiving data of external RS485 communication ports A4 and B4 and sending the data to the second microprocessor;
the switching circuit is connected with the second microprocessor, the second microprocessor controls the switching circuit, and external communication ports A5 and B5 of the switching circuit are selected to be connected into the third RS485 transceiver circuit or the RS485 receiver circuit, so that the slave equipment is in different running states;
the RS485 communication port of the master device, which is arranged outside, is connected with an RS485 bus, and the external communication ports A5 and B5 of each slave device are sequentially connected to the RS485 bus;
the circuit of the main equipment comprises a first RS485 receiving and transmitting circuit and a second RS485 receiving and transmitting circuit; the first RS485 receiving and transmitting circuit is connected with the first microprocessor and is provided with external RS485 communication ports A1 and B1; the second RS485 receiving and transmitting circuit is connected with the first microprocessor and is provided with external RS485 communication ports A2 and B2; two external RS485 communication ports A1 and B1, A2 and B2 of the main equipment have independent data transceiving functions;
two sets of RS485 communication ports A1 and B1, A2 and B2 which are arranged outside the main equipment are connected into an annular RS485 bus; the external communication ports A5 and B5 of each slave device are sequentially connected to the annular RS485 bus;
the second microprocessor of the slave device is also connected with a storage unit and is used for storing software faults in RS485 communication;
when the switching circuit selects the external RS485 communication ports A3 and B3 of the third RS485 transceiver circuit to be connected with the external communication ports A5 and B5 of the switching circuit, the slave device is in a communication state, and when the switching circuit selects the external RS485 communication ports A4 and B4 of the RS485 receiving circuit to be connected with the external communication ports A5 and B5 of the switching circuit, the slave device is in a detection state, and the slave device is in the detection state by default; when the slave device in the detection state receives the data packet P2, the slave device is switched to the communication state, and uploads the data packet P3 through the external RS485 communication ports A3 and B3 of the third RS485 transceiver circuit; when the slave device in the "communication state" receives the packet P4, the packet P5 is uploaded; each time the slave device is switched from the communication state to the detection state, the system initialization operation is carried out; when the slave device is in a communication state, the slave device is automatically switched to a detection state when the data packet P4 is not received in the period T;
the data packet P5 contains software failure in RS485 communication;
the circuit for automatically detecting the RS485 communication fault adopts the following method for automatically detecting the RS485 communication fault, and comprises the following steps:
step S1, the master device stops sending data, waits for N seconds, N > T, all the slave devices are switched to a detection state, and the slave devices perform system initialization operation;
step S2, the master device sends a packet P2 to the first slave device, and the first slave device switches to "communication state" after receiving the packet P2, and uploads a packet P3 through the external communication ports a5 and B5;
step S3, if the master device does not receive the data packet P3, recording that a hardware fault point exists between the master device and the first slave device, ending fault detection, and updating a fault code table;
if the master device receives the data packet P3, the master device continues to send the data packet P4, and uploads the data packet P5 after receiving the data packet P4 from the first slave device; the data packet P5 contains software failure in RS485 communication read from the storage unit;
after receiving the data packet P5, the master device analyzes the data packet P5 to determine a software fault and updates a fault code table;
step S4, completing the detection of the first slave device, and detecting the next slave device according to the steps S1-S3;
in the above process, when the switching circuit selects the external RS485 communication ports A3, B3 of the third RS485 transceiver circuit to connect with the external communication ports a5, B5 of the switching circuit, the slave device is in the "communication state", and when the switching circuit selects the external RS485 communication ports a4, B4 of the RS485 receiver circuit to connect with the external communication ports a5, B5 of the switching circuit, the slave device is in the "detection state", and the slave device is in the "detection state" by default; when the slave device is in the "communication state", it automatically switches to the "detection state" when the packet P4 is not received within the period T.
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| CN109993958B (en) * | 2019-05-08 | 2021-06-11 | 深圳市共济科技股份有限公司 | Data acquisition system and method of RS485 bus |
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| WO2011011915A1 (en) * | 2009-07-29 | 2011-02-03 | 华为技术有限公司 | Data communication method, communication equipment and communication system |
| CN103326911A (en) * | 2013-07-03 | 2013-09-25 | 富盛科技股份有限公司 | Self healing ring RS485 bus structure with short circuit and circuit break prevention |
| CN105656656A (en) * | 2014-11-26 | 2016-06-08 | 上海协同科技股份有限公司 | RS485 communication circuit and fault detection method of nodes applying the circuit |
| CN107294827A (en) * | 2017-05-27 | 2017-10-24 | 烽火通信科技股份有限公司 | The RS485 communication systems and method for avoiding master-slave equipment from conflicting |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7676839B2 (en) * | 2004-03-15 | 2010-03-09 | Xceedid | Systems and methods for access control |
| CN104104542B (en) * | 2014-07-16 | 2017-11-03 | 深圳市海亿达能源科技股份有限公司 | RS 485-based real-time intelligent obstacle removing method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011011915A1 (en) * | 2009-07-29 | 2011-02-03 | 华为技术有限公司 | Data communication method, communication equipment and communication system |
| CN103326911A (en) * | 2013-07-03 | 2013-09-25 | 富盛科技股份有限公司 | Self healing ring RS485 bus structure with short circuit and circuit break prevention |
| CN105656656A (en) * | 2014-11-26 | 2016-06-08 | 上海协同科技股份有限公司 | RS485 communication circuit and fault detection method of nodes applying the circuit |
| CN107294827A (en) * | 2017-05-27 | 2017-10-24 | 烽火通信科技股份有限公司 | The RS485 communication systems and method for avoiding master-slave equipment from conflicting |
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