We stock Siemens S5-90U. This is the simpliest product series within the Siemens SIMATIC S5 family. It's a compact PLC with built-in digital inputs and outputs, but it can also be expanded by using S5-100U I/O modules. The system was phased out a long time ago but we can offer used/refurbished Siemens S5-90U spare parts from our stock.