The Siemens 3RK2400-1BT30-0AA3 is a K20-series digital I/O module built for field deployment — IP67 rated, no enclosure needed. It gives you 2 PNP inputs and 2 PNP outputs in a 20 mm wide body that mounts direct to machine frame or conveyor rail without a backplate. Each output is rated for a continuous 1 A at up to 30 V DC, but the module requires an external 20–30 V DC PELV supply (per VDE 0106, protection class III) to power the output circuits — the sensor supply from the bus coupler alone won't cut it.
IO map and wiring reality
The four M12 sockets are pinned consistently: Pin 1 is sensor supply L+, Pin 3 is sensor supply L-, and Pin 4 carries the signal — but which signal depends on the socket. Sockets 1 and 2 map to inputs IN3 and IN4 (D2, D3); sockets 3 and 4 map to outputs OUT1 and OUT2 (D0, D1). Outputs use 3-wire technology with Pin 3 as ground and Pin 4 as the switched PNP output. The module is an A/B slave with ID/ID2 code A/0, addressed via the M12 connector. Built-in watchdog, short-circuit protection, and induction suppression are standard — no external diode needed on the output side.
Environmental and signal specs
Shock rated at 15 g for 11 ms. Input signal threshold: <0> at ≤1.5 mA, <1> at ≥6 mA. Outputs display yellow LED per channel; green LED confirms auxiliary supply present.