Applies To:
  • CitectSCADA 1.00, 1.01, 1.10, 1.11, 1.20, 2.00, 2.01

Question: I am getting the following errors from my Tiway PLCs. 'Unit not responding', 'Unit off-line, cannot talk' and 'Channel off-line, cannot talk'. These errors occur once every few hours, while the rest of the time communication is OK. What is causing these errors? 

These errors are usually generated by incorrect installation of a Tiway network. Most likely you have two Tiway cards on the same network, or are trying to use a single NIM for two different Tiway networks.

See also Q1097