Applies To:
  • VijeoCitect v6.10, v7.xx 

 I am connecting to OFS (Schneider Electric's OPC Factory Server) via OPC and I am randomly getting #coms and losses of communication. This becomes more apparent on pages with a high number of dynamic objects.

When I review the OFS logs, I see multiple error messages "spurious messages" followed by a timeout.

 The "spurious message" indicates that the PLC is overloaded and OFS is receiving responses from the PLC too late.

The inherent issue lies with PLC loading, however from a VijeoCitect perspective, the following settings may help reduce the load on OFS, which in turn will reduce the load on the PLC.

UseAsyncWrites = 1
Timeout = 5000
Delay = 100
IOServer.IODevice.Update = 3000   //Increase this value to an acceptable update  time in seconds

Also in the OFS Configuration tool, the following settings have been shown to reduce this issue:
Device Timeout = 30000
Frame Timeout = 10000
Max Channels = 4
Max Pending = 255

The underlying issue is PLC overloading, but these parameters have been shown to assist in reducing the load on the PLC.

It should also be noted that it is advised to use the OFSOPC driver instead, as this driver is optimised to talk to the OFS server.