What it is and what it does
The 6AG1131-4BF50-7AA0 is the SIPLUS variant of Siemens’ ET 200S 8-channel digital input module (base order 6ES7131-4BF50-0AA0). It reads 8 digital 24 V DC inputs, with the unusual threshold that signal “1” is −15 to −30 V and signal “0” is −5 to +30 V — so it expects a negative-going voltage for the ON state. That’s a critical detail if your sensor outputs are positive-logic or pull-up; verify the sensor wiring before slotting it in. The module draws 1.2 W typical from the backplane bus, switches in 2–4.5 ms, and accepts 2-wire sensors with a quiescent current up to 1.5 mA. No parametric settings, no diagnostics — it’s a straight-through digital input slice with per-channel green LEDs.
Mounting and integration notes
Mounts on the ET 200S terminal module (TM-E). Occupies one slot; uses the same backplane bus connector. Cable lengths: 600 m unshielded, 1 000 m shielded. Input filter delay is fixed at 2–4.5 ms (rise and fall identical). Reverse polarity protection on the input side is standard. No group error LED — each channel has its own green indicator. Isolation between channels and the backplane bus is tested at 500 V DC, so the common-mode rejection is solid. Power is drawn entirely from the 24 V DC backplane; the supply current depends on the encoder load. No external supply needed. Ambient temperature derating follows altitude: full range to 2 000 m, then Tmax -10 K to 3 500 m, then -20 K to 5 000 m. Maximum altitude 5 000 m.