Dear Fellows: I am working with a SCADA System Integrator. It is a Windows NT, Ethernet/TCP-IP bases SCADA system. I have run into a terminology issue with my contractor. Here is the issue. Any time and due to any reason if the SCADA I/O server is not able to receive any or all of its data from a certain PLC, the SCADA I/O server declares it as a communication failure. SCADA I/O server does not care about the reason for not getting data. The communication with the PLC NIC may be perfectly fine but the I/O server will declare this as a communication failure. I don't agree with this. I think as long as the I/O server can talk to the PLC NIC the communication is perfectly fine and I/O server should not call it as a communication failure. The I/O server, based upon its built in intelligence and to the best of its capacity should try to identify the actual cause of not getting data from the PLC. For, example there was a problem with the PLC, a CRC error, or a short message error etc etc..... This way the system operator will readily know the real cause of not getting data and will not have to tackle the issue of communication failure (switch / router failure etc etc) because communication did not fail. Any comments will be appreciated...