Have a customer that has a running 1756-l83es, communicating to redundant ABCIP IO servers for Wonderware 2020. This configuration has been running a little over a year.
Had an extended 2 week downtime, and upon restart the WW apps would not communicate to the L83. There's about a dozen WW HMIs that hit this PLC and none of the tags on those apps would update. The IO server diagnostics showed all green, as in valid tags, but all values were 0. Things tried:.
Cycle power on PLC
Cycle power on IO servers
Ping PLC from IO PC...fine
Create new topic in IO server, no help
Go online with PLC with studio (ver 32), no issues
Connect laptop directly to L83 with local IO server and test app, still no comms
Finally, they re downloaded the program to PLC, and it started communicating again.
I had never experienced this scenario before...Ive had ABCIP topics become corrupt, but recreating them always resolved. It almost seems like the PLC was in some memory protect mode that was disallowing CIP Connections. However, peer to peer message instructions to other PLCs were still working. Run to Program to Run or even power cycles wouldn't revive it, only a download of the program again.
Any thoughts as to what could have happened?
Had an extended 2 week downtime, and upon restart the WW apps would not communicate to the L83. There's about a dozen WW HMIs that hit this PLC and none of the tags on those apps would update. The IO server diagnostics showed all green, as in valid tags, but all values were 0. Things tried:.
Cycle power on PLC
Cycle power on IO servers
Ping PLC from IO PC...fine
Create new topic in IO server, no help
Go online with PLC with studio (ver 32), no issues
Connect laptop directly to L83 with local IO server and test app, still no comms
Finally, they re downloaded the program to PLC, and it started communicating again.
I had never experienced this scenario before...Ive had ABCIP topics become corrupt, but recreating them always resolved. It almost seems like the PLC was in some memory protect mode that was disallowing CIP Connections. However, peer to peer message instructions to other PLCs were still working. Run to Program to Run or even power cycles wouldn't revive it, only a download of the program again.
Any thoughts as to what could have happened?