4-channel isolated barrier, 24 V DC supply (Power Rail), Dry contact or NAMUR inputs, 50 % less wiring, 2:1 technology, Relay contact output, Line fault detection (LFD), Reversible mode of operation, Housing width: 20 mm, Number of channels: 4-channel, 2:1 Method, Rated voltage: 19 ... 30 V DC, Field device: NAMUR sensor, Field device [2]: volt-free contact, Line fault detection, Type: 4 x relay (NO contact), Reversible mode of operation