What this module does on an S7-1200 rack
The Siemens 6ES7223-1BH20-0XA0 is an EM 223 expansion module that adds 8 digital inputs and 8 digital outputs — each channel runs at 24 VDC, with the transistor outputs rated 0.5 A per channel. It snaps onto the right side of the CPU, extending the I/O count without changing the backplane or power budget. The module draws its field-side power from the 24 VDC sensor supply, not the CPU bus.
Input/output specs that decide the fit
Eight sourcing inputs accept 24 VDC nominal. The eight transistor outputs sink 0.5 A continuous each. The 0.5 A per-output ceiling means each channel drives a small solenoid, indicator lamp, or contactor coil directly — but a group of outputs feeding a larger load needs an interposing relay. Total module current from the 24 VDC supply is limited by the CPU's backplane current budget.