The Siemens 3RK2200-2CG00-2AA2 is a Slimline Compact I/O module for control-cabinet use, part of the AS-i SC22.5 family. It provides 4 digital inputs (PNP Type 2, 3-wire) on an A/B slave profile (S-0.A.0). The module draws 200 mA when powered solely via the AS-Interface bus, or 500 mA when an external auxiliary supply (Uaux) is connected — that extra headroom matters if you're driving the inputs from a longer cable run or need to power additional sensors off the same bus segment. The auxiliary feed must be 20–30 VDC, PELV per IEC 60990, protection class III. The module itself is rated IP20, so it lives inside a clean, dry enclosure — not on the machine frame. Mounting is screw or snap-on onto a DIN rail; the 22.5 mm width and 100 mm height mean it fits a standard 22.5 mm slot in a panel layout.
Power supply split — the detail that matters
The module's supply current splits cleanly: 200 mA from the AS-i bus (8.5 V nominal) when running on bus power alone, or 500 mA when you add the external 20–30 VDC auxiliary supply. The auxiliary supply also feeds the output circuits — there are no digital outputs on this variant, but the 4 A rating on the external auxiliary voltage tells you the module can handle a fair sensor load downstream. If you're using AS-i Power24V, the module supports that too, pulling up to 270 mA at 24 V.
Integration notes
The module uses 2- and 3-wire connection technology. Solid wire: 1x (0.5–1.5 mm²) or 2x (0.5–1.5 mm²); stranded with ferrule: 1x (0.25–1.0 mm²) or 2x (0.25–1.0 mm²). AWG equivalents: 20–16 solid or stranded. Address setting is via the front addressing socket; the factory-set ID1 code is 7, changeable. Input status shows via yellow LEDs on the front face.