Phoenix Contact shared an update PostedMonday, March 30,2015 at 9:23 AM PLC Logic is a programmable relay micro controller that is ideally suited for small automation applications. PLC Logic allows users to switch and control I/O signals using a single system. The pluggable logic modules pair with our slim 6.2 mm electromechanical or solid state PLC relays to form a space-saving micro controller, measuring only 50 mm wide. No additional space on the DIN rail is used because it is connected directly on to the PLC relays. The relays are replaceable, which means there is no need to shut down the system and rewire between control and interface levels.