IO devices connect large numbers of sensors / actuators. Compact dimensions, clear operation, easy troubleshooting are essential aspects. The PSSuniversal 2 system was developed completely from scratch. Particular emphasis was placed on the mechanics in terms of its practical use and esthetic demand. By using a consistent three-piece architecture, set-up and service handling were optimized. Mounting space was reduced without having to abandon optical status indication and clear labeling. Connectors are such that peripherals are exactly terminated at a single point. Traditional brand colors are indicating standard and safety-related control functions.