Siemens 6ES7221-1EF00-0XA0 is an EM 221 digital input module for the SIMATIC S7-200 family, delivering eight optically isolated digital inputs for 120 V AC signals. It is designed for use with S7-21X CPUs, enabling safe interfacing of 120 V AC sensors and switches to a compact PLC I/O bus. This legacy EM 221 DI card is listed as discontinued by Siemens, so users planning new designs should consider current replacement options or migration paths when updating their automation architecture.
