The ABB TU890 is a compact Module Termination Unit (MTU) designed for the S800 I/O system. This passive unit serves as a base for mounting a single I/O module, providing essential connections for the redundant optical ModuleBus and power supplies. It features a 24-pin D-Sub connector for simplified and secure termination of process signals. The TU890 is specifically engineered for redundant I/O configurations, ensuring high availability and reliability in critical industrial automation applications within the ABB System 800xA environment.