A wide range of I/O modules is offered including AI, AO, DI, DO, temperature input functions and pulse frequency. Each module handles 4 I/O channels (DI: 8 channels) in a slim, 20 mm wide package. The DI module is additionally software-configurable to operate with a combination of NAMUR switch inputs and ultra low-power solenoid outputs. The temperature input module can accept inputs from thermocouples or RTD sensors. A mechanical keying system ensures that modules cannot be replaced into wrong slots on the carrier during maintenance work.