S7-200 expansion — what this EM 222 module does and where it fits
The 6ES7222-1BF22-0XA0 is the SIMATIC S7-200 EM 222 digital output expansion module, carrying 8 outputs at 24 V DC, each rated 0.75 A for resistive and inductive loads. It is a spare part designated exclusively for S7-22X CPUs — it will not work with later S7-1200 or S7-1500 racks. Each group of 4 outputs shares a common return and a 3 A group current limit at both 40 °C and 55 °C ambient, so the per-channel 0.75 A rating holds across the full operating range without derating.
Output ratings and wiring constraints
The module draws 50 mA max from the 5 V DC backplane bus and dissipates 2 W typical — negligible thermal load in a crowded S7-200 rack. There is no built-in short-circuit protection on the outputs; each channel relies on an external fuse or PTC per group. Inductive kickback is clamped to L+ (-48 V), which protects the output transistor and any parallel contacts. Signal '0' residual current is 10 µA max — low enough to avoid ghosting on a PLC input or relay coil. The minimum '1' signal voltage is 20 V, with a permissible range of 20.4 V to 28.8 V DC.
Isolation and cable runs
Channel-to-backplane isolation uses optocouplers, tested at 500 V AC. Shielded output cables can run up to 500 m; unshielded runs are limited to 150 m.