The PLC Logic system combines basic programmable logic capability with PLC relays, creating a “smart” relay system. The system houses the logic in a small module that plugs into a block of eight PLC relays. The pluggable logic modules are compatible with many of the company’s electromechanical and solid-state relays and are available in various voltage ranges. When connected to a set of eight relays, the system measures 50 mm wide. A hot-swappable relay capability allows individual relays to be replaced without shutting down the entire system.