Modbus rtu

[callizehra]

Hello, I want to read data from the engine with modbus rtu but I read zero data from the engine and also see data 5 and 4 in the error message of the rir block. i am using unitronics v700.

modbus.vlp

[kratmel]

It looks like you use panel as master and engine as slave.

Master named ID1   and  you try to read data from slave ID1 --- it is not correct.

Please change this nodes to different ID and try to read needed data.

You can change ID on engine to 2 or if it imposible - change master PLC ID to another one.

 

[callizehra]

Thanks for your reply, I have made the necessary changes but it still gives a communication error.

[kratmel]

Please post your modbus setup. Motor and drive nameplate and how modbus wires is connected to V700.  Sometimes A & B RS485 wire is swaped.

If you use USB connection to V700 - com port 1 is not work with modbus - it is connected to USB and Visilogic.

If it possible please use PC Modbus software and USB to R485 connection for test drive communication.

Please note - In drive parameter - you must configure communication settings drive ID  and enable Modbus communication.

[stembera]

Just a two suggestions: 
1. Your software communicates via COM1. If you connect your PC via USB port of the PLC, COM1 will be suspended so the Modbus comm will not work.
2. You configure COM1 port as RS485. You must do the same on DIP switch on the PLC. Factory default is RS232.