I just set up a machine with a BRX PLC and a Nitra PAL valve bank. The valve bank is controlled via Ethernet I/P. I set up the EtherNet I/P Scanner in Do-More. I've set the RPI under both Input and Output to 10 milliseconds.

This all works, but I've been having trouble with the communications randomly dropping between the BRX and the PAL. The NS light on the PAL blinks red a few times due to the lost scanner connection, and then it re-establishes connection and keeps on going. I configured the PAL to hold the last state of the valves if the connection is lost, so it doesn't cause serious problems when the communication is lost, but of course I want to get this resolved so it hopefully doesn't happen at all.

I had tried setting the RPI to 50 milliseconds, but that did not resolve the problem.

I've attached some Wireshark captures of the communication between the PLC and the PAL, also a screenshot of the capture where the connection closed and reopened. In the time I had Wireshark capturing, the communication dropped 3 times. I noticed a pattern; there is an Encapsulation Sequence Number, and every time that it rolls over at 65535, the connection appears to close and then reopen. It was exactly the same for all 3 of the disconnects that I captured. I don't know enough about this stuff to know what's going on or how it should be working, but this doesn't seem right.

In the Wireshark capture, the PLC is 192.168.141.99 and the PAL is 192.168.141.12