I have an installation that uses a 961EN to transmit two analog signals over Modbus/TCP to a 972EN that converts them into analog signals for an older PLC.
The two sites are connected with single-mode fiber and Cisco Catalyst switches and have excellent network connectivity. (1-5 ms ping time with no dropped packets).
The problem I am having is that outputs from the 972EN to the PLC go to zero at random times. They usually stay that way for about 5 seconds then restore to their correct values.
When pinging each device, I get numerous dropped packets and a fair amount of jitter (ping times from 2ms up to 3500ms). This is regardless of whether or not the device is local (i.e. connected to the same switch) or remote (connected over fiber to the other switch). Pinging other devices on the same switch yields ping times of 1-2 ms consistently with no dropped packets.
So, I am thinking that I may have some defective devices, but wanted to reach out and see if this ping behavior is normal or not. Or - are there any firmware updates for these ?