The module also carries electronic short-circuit protection with a trip threshold between 0.7 and 1.8 A, so a crushed cable won't take out the backplane bus.
Fit and wiring
The module sits on an ET 200SP base unit (BusAdapter required). Input voltage is 24 V DC, and the module draws 300 mA from the backplane plus 4 W typical. Isolation between channels and the backplane bus is tested at 500 V DC, so it shrugs off the kind of noise you get from a VFD or motor starter sharing the same panel. The green status indicator on each input lets you walk the route and spot a dead sensor without dragging out a meter. The group error LED (red) and diagnostic alarm tell the PLC something's wrong before the line stops.