The fault was not only on AI880 but also on other IO cards . On AI , AI as DI card the error was gone after disabling the unconnected channels on each card from CB hardware. The errors persists though on DO cards . My question: for unused channels on DO880 cards , even if disabled ...must we close the channel phisicaly with a EOL resistor for the warning to disappear?
Problem solved. Issue happened because i disabled the spare channels while in faulty state and then removed the line monitoring from the settings . The warning remained latched and could not be reseted. I had to re-enable the channels and remove the line monitoring . Warning was gone and could be reset. Disabling the spare channels was not necessary after removing the line monitoring as all warnings and errors disappeared.