What this NAMUR module is and why it's specified
The Siemens 6ES7131-4RD00-0AB0 is an ET 200S electronic module providing four NAMUR-rated digital inputs (24 V DC) in a 15 mm-wide slice with per-channel green status LEDs and a red group-fault LED (SF). It carries a diagnostic alarm that can be set and electronic short-circuit protection, meaning the module can detect a fault and signal it to the controller before a misread or wiring failure escalates.
The module draws 45 mA from the 24 V DC supply and dissipates 1.6 W typ.—both numbers to add to your ET 200S backplane power budget. Switching times are symmetric: max. 4.6 ms for both turn-on and turn-off. Isolation is tested at 500 V DC between channels and the backplane bus.
Where this ET 200S slice belongs
This 4DI NAMUR module is used in distributed I/O stations (ET 200S) where the input sensors operate on the NAMUR standard—common in chemical, oil & gas, and pharmaceutical plants for proximity detection in potentially explosive atmospheres or where signal integrity is critical.