The Siemens 3RK1901-2NR20 is an AS-Interface accessory that transitions the AS-i flat cable to a single M12 socket, carrying both AS-i power (26.5...31.6 V per the AS-Interface specification) and auxiliary power on the same connector. Rated for 4 A continuous, it handles the current draw of a small sensor cluster or actuator node without needing a separate power tap. The IP67/68/69K rating means the housing and M12 connection survive high-pressure washdown and temporary submersion — standard for food, beverage, and washdown-zone deployments where hose-down cleaning is routine.
Mounts via screw fixing with a specified tightening torque of 1.65 N·m. The electrical connection uses an insulation-piercing method for the AS-Interface flat cable — no stripping required, just clamp and tighten. Socket pin assignment: pin 1 = ASI +, pin 2 = AUX -, pin 3 = ASI -, pin 4 = AUX +. The note "cable must not end in the feeder" means the flat cable must pass through this tap point and continue to the next node or terminator — this is a mid-line tap, not a line-end terminator.