If you were talking about the PLC we designed
correction: the uC controller we designed to replace the PLC.

One problem what we faced during the replacement of the PLC with a uC card was the never ending changes made in the specs. Also note that its a bit tough to add any additional features if its not planned properly. Hardware changes are very expensive

Thew very argument for thinking twice (naah, three times) before replacing a PLC with a uC controller.

Erik