The Siemens 3RK1901-1NR21 is an AS-Interface M12 branch cable assembly, 1 m long, that transitions the AS-i flat cable to an M12 connector for a single device drop. It carries both AS-i power and auxiliary power (Uaux) on the same M12 socket, with the pinout: 1 = AS-i +, 2 = Uaux -, 3 = AS-i -, 4 = Uaux +. The insulation-piercing connection method taps directly into the flat cable without stripping. Rated for 4 A maximum load, it supplies the connected sensor or actuator from the AS-i bus and the auxiliary 24 V loop. The operating voltage range per the AS-Interface specification is 26.5 to 31.6 V. The IP67/68/69K rating means the M12 socket and the piercing head are sealed against dust ingress, temporary submersion (IP68), and high-pressure hot-water washdown (IP69K) — suitable for food-and-bev lines or outdoor conveyor sections where hose-down cleaning is routine.
Mounts via screw fixing to the machine frame or panel, not DIN rail. The 1 m cable length gives some routing flexibility to reach the device from the AS-i trunk line.