22.5 mm AS-i slice for control-cabinet I/O
The Siemens 3RK2402-2ME00-2AA2 is a Slimline AS-Interface module packing 4 digital inputs and 2 relay outputs into a 22.5 mm wide housing that screws or snaps onto DIN rail — the standard footprint for a compact cabinet slice. The module operates as an A/B slave with profile S-7.A.0, addressable via the front socket, and draws 200 mA from the AS-i bus or up to 500 mA when sensor power is supplied through the separate Uaux feed — a key distinction when budgeting the AS-i power supply.
Sensor supply split — AS-i bus vs Uaux
The module's note explicitly separates sensor supply paths: with supply via the AS-Interface cable, the module draws 200 mA; with supply via the auxiliary voltage Uaux (20 to 30 V DC required), it draws 500 mA. If the sensors are powered from the AS-i bus, no additional power supply is needed — the 8.5 V from the AS-Interface line feeds the inputs. If higher sensor current is required, the Uaux feed handles up to 4 A for external sensors, with the module itself taking up to 500 mA from that rail. The thermal current rating is 5 A through the relay contacts, and the AS-Interface supply path is rated for 2 A — so the limiting factor in a multi-drop run is the bus current budget, not the module's own draw.