Plc5/40b

I have the PLC-5/40B and I have issue communicating to PLC.
When I configure driver it configures successfully but after few minutes Comm. error 00000005 comes, when I configure driver again it configures successfully. But the Status shows Faulted, after sometime it goes to Comm. error 00000005. Have anyone noticed this?

What port, cable and are you using a USB adapter?

It uses USB adapter for Serial connection and also Ethernet connection for connecting to SCADA

Odds are its your USB adapter, the 5/40B does not have Ethernet so that must be another card in the rack

The PLC-5/40B might have a 1785-ENET "sidecar".

Which driver gets the error; serial, Ethernet, or both ?

Where, precisely, is the error code indicated ? In RSLinx, in your SCADA, or in RSLogix 5 ?

Are there any other changes to they system that have been done recently ?