The Siemens 3SF5811-0AB08 is an AS-Interface emergency-stop slave with a 22 mm mushroom pushbutton and positive-opening contact block. The slave type is F slave, 2I, reporting E-stop state as two input bits over the AS-i bus.
Mounts in a standard 22 mm round panel cutout. The enclosure is square-fronted, 85 mm wide by 85 mm tall by 106 mm deep. Fastening is vertical or horizontal, and the delivery state is pre-wired on a strip terminal — no separate wiring of the AS-i flat cable required; the slave clips directly onto the yellow AS-i cable. The rotate-to-unlatch mechanism means the operator twists the mushroom head to release it after an emergency stop, not a key or a pull. A protective collar is included to prevent accidental actuation from side impact.
What the 2 Switching Elements Give You
Two switching elements means the contact block provides two independent NC contacts. In a safety circuit, one NC contact typically goes to the AS-i slave input, and the other can be wired in series with a hardwired safety relay or PLC input for redundancy. The DC rated voltage for the contacts is 30 V — consistent with the AS-i bus voltage (typically 30 VDC). No light source or lamp holder is included — this is a pure pushbutton, not an illuminated E-stop.