I have three legacy Compact Logix PLCs that I am having communication issues with. They are 1768-L43 version 20.18. Whenever we attempt to go online we are getting errors, and they are not always the same error. Errors are:
Failed to go online with the controller. Controller type is not supported
Communication request failed
Failed to go online with the controller. Unconnected message timeout.
To add this rack has two ENBTs. Both seem to be communicating fine. One is for IO, drives, etc. The other is plant communications. We have good communications back to our HMI system that is going through the plant network.
We have reached out to Rockwell and talked with three different techs and go nowhere. We also had our IT group roll back our security updates to see if one may have killed the connections. Also nothing.
Has anyone seen any issue like this or similar, and have any ideas on where to start?