Two Masters & One SLAVE

Hi to All Guys,

Plz reply my this probelm,.......A single SLAVE PLC can Communicate with two Master PLCs (Of different Brands) at a time..................??????

Best Regards,

Yes, if you use MODBUS TCP. On Modbus Serial , NOT Possible. (This is about Schnieder systems,must be same about others)

Thanx for replying.

My Slave PLC is already communicating with a Master PLC using Modbus Serial (through RS485 Port).

Now I want to communiate the same Slave PLC with another Master PLC using Modbus TCP. Is it possible .....???

Go ahead it will communicate with both masters. As they are already on TCP,ensure different node addresses.

I'd say, "it depends" on the slave's firmware implementation of Modbus.

The slave's data is in the Modbus registers, but the question is whether the slave will respond to both a serial port request and a TCP (ethernet) port request, which is a slave firmware issue.

Just because a device has an ethernet port, doesn't mean that the Modbus is accessible via ethernet.

It would be very easy to test with a PC running one of the Modbus Master simulator programs, like Modscan32, or Simply Modbus, or Modpoll, configured for Modbus TCP on the ethernet port.