I was called to one of my customer this morning who has one of tha above PLC,s. The problem is that there is a remote rack and it is not talking to the main rack and the PLC is not in run mode. There is also DA001 analog module in the remote rack which was in error. I exchanged both the RM201 and RT201 modules the comms is still not working but the analog module is now in run. Both the Rm201 and the R201 are in alarm. The alarm is described as a duplex bus or intelligent I/O unit. The cable between the two units buses out ok.
any help on this would be appreciated