Modbus poll framing error
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Freemodbus It's a free protocol stack, Only the slave station is supported.
![modbus poll framing error modbus poll framing error](https://res.cloudinary.com/campbellsci/image/upload/w_600,h_600,c_limit,f_auto/8496.png)
Modbus It's a master-slave communication structure, There is only one master station in a system, Others are slave stations. Modbus Protocol is one of the most common fieldbus protocols, Its design and use are simple, Reliable operation, In the PLC 、 Instruments and Apparatuses 、 It is widely used in sensors, among, be based on RS485 Physical interface Modbus The bus is used most. In industrial application, It's going on RS485 When it comes to circuit design, In order to ensure electrical safety and anti-interference, Signal isolation is often done, Optocoupler isolation is a common form. Key word :RS485 Isolation Freemodbus Optocoupler sequential
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#MODBUS POLL FRAMING ERROR SERIAL#
The serial port sends and receives signals and RS485 The transceiver enable signal of the chip is isolated by optocoupler, In the course of testing, we found that there were occasional TimeOut The problem of, After searching and analyzing, It is found that it is caused by the delay of optocoupler signal, The solution is given, And the problems are analyzed in detail. Freemodbus Is a free and practical protocol stack, Kong Binghuo ( WeChat official account : Kong Binghuo ) Using it to realize a slave station. Abstract : be based on RS485 Physical interface Modbus Bus is widely used in industrial control.