MODBUS MASTER AND SLAVE on S7-200

[VCControls]

Has anyone ever attempted to run Master and Slave MODBUS RTU on 2 different ports on the same PLC. Just curious how you tackled the timing issues between the handling slave requests while attempting to keep a routine master control from the other port. I have successfully implemeted a master and also a slave, but never attempted both at the same time.

 

[Tom Jenkins]

If you are using two different ports, one as a master and one as a slave, there is generally no problem. I haven't done it on Siemens, but I have on many other brands and I would not expect Siemens to be THAT different.

Each port is essentially independent on most PLCs. Each port has its own address, its own baud rate etc. and its own comm driver.

 

[Fredk]

Hi,

Anybody ever had a chance to try this out?

Fred