The Siemens 3SF1244-1LC05-1BA2 is a SIRIUS mechanical safety switch with ASIsafe communication, built for guarding applications where a positively opening contact must break the safety circuit when the guard opens. It carries a 24 V LED for bus power indication and is rated IP66/IP67, so it handles washdown environments in food, beverage, or pharmaceutical lines without needing an external enclosure.
Repeat accuracy of 0.1 mm means the switch detects the actuator position within a tenth of a millimeter every cycle — important for consistent safety distance calculations on hinged or sliding guards. The positive opening action is a mechanical guarantee per IEC 60947-5-1: even if contacts weld, the actuator force physically breaks them open. That's the feature that makes this a safety-rated device, not just a limit switch. The 24 V LED confirms AS-Interface bus power is present at the switch.
Screw fixing, block-style housing, 50 mm wide. The M12 plug (4-pole, fixed) carries ASI+ on pin 1, ASI- on pin 3; pins 2 and 4 are unassigned. The ASIsafe channel 2 loops through to an M12 socket on the right side of the housing — that daisy-chain pass-through saves a tee connector when linking multiple safety switches on the same bus segment.