The 3RK2200-0CG02-0AA2 is a Siemens SIRIUS AS-Interface slave module in the SlimLine S22.5 form factor. It brings four digital inputs (PNP transistor, 3-wire technology) onto the AS-i bus without any outputs onboard, so it is a pure sensor-gathering node for a control cabinet. This module is an A/B slave (ID/ID2 code A/0), meaning it can coexist on the same AS-i network line with standard slaves—useful when you are packing more I/O points per cable run without adding a second gateway. An external auxiliary supply of 20 to 30 V DC is required for the output circuits; do not assume the AS-i bus cable powers the load side. That supply must comply with VDE 0106 (PELV), protection class III.
The four digital inputs are PNP type, so if your sensors are NPN (sinking) you will need an interface or a different module. Input switching level high starts at 10 V; signal <1> minimum 5 mA, signal <0> maximum 1.5 mA—that matches standard 24 V DC proximity switches and limit switches. Maximum current draw from the AS-i bus is 270 mA total, and at 40 °C ambient the module can deliver 200 mA to the load side from the auxiliary supply. The module itself draws from the bus for its own electronics, so keep that 270 mA headroom in mind when daisy-chaining multiple slaves on one segment. The SlimLine S22.5 width is 22.5 mm, so it takes up one standard DIN-rail slot. Mounting is on 35 mm standard rail or wall-mount with push-in lugs. The front addressing socket lets you set the AS-i address without removing the module from the rail.
This module lives inside a control cabinet (IP20, no washdown rating). The spring-loaded terminals accept 2 x (0.25 to 1.5) mm² solid or stranded, or 2 x (0.25 to 1) mm² with end sleeves, or AWG 2 x (24 to 16). The detachment tool for the spring terminals is listed as an accessory. Status LEDs on the front: green AS-Interface (bus communication), yellow per input (I/O state), red FAULT. That covers the basics—no mystery troubleshooting.