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Hello:

I am having trouble to communicate my V1040 with an existing Schneider Electric M221 with the serial port. It was supposed to be easy, but I don't receive any answer from the M221.

V1040 has 2 ports, and I am using port 2. The port has been set up for RS485 with termination with the DIP switches. MODBUS protocol is:

Baud rate: 19200

Parity: NONE

Stop Bit: 1

wires has been checked and also pinout. My first concern is about the pinout. Schneider requires 3 wires on RS485. It uses D1, D0 and ground, while V1040 only uses A+ (D1) and B- (D0), but no ground as reference. 

The V1040 is the MASTER and has ID1 and the M221 is setup with SLAVE ID 3, and the only line on this PLC is to set a value on %MW1 with the value of %MW0

A very simple program attached is made to read a Holding Register Addressed 1 (%MW1) and this value should be displayed on the Touchscreen. 

While reading the execution, the status messages I receive are 4 and 5 only. This means I have no communication.

 

I really need help on this. Please advice. 

Prueba MODBUS.vlp

Prueba MODBUS.smbp

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