The Siemens SIMATIC S7 has digital input SM 326 with 24 V DC supply it has fail-safe NAMUR input for SIMATIC S7 F-systems. It is up to category 4 (EN 954-1)/ SIL3 (IEC61508)/PLE (ISO13849), 1x 40-pole.
Power loss: 4.5 W Reverse polarity protection 8 digital inputs
