Siemens 6ES7-221-1BH30-0XB0 Digital Input Module

Siemens 6ES7-221-1BH30-0XB0 is a SIMATIC S7-1200 digital input module (SM 1221) that provides 16 x 24 V DC input channels wired as sink or source (NPN/PNP). It accepts standard 24 V DC signals from sensors, switches, and other digital devices, converting them into PLC inputs for the S7-1200 CPU. The module is listed as SM 1221 with 16 x 24 VDC inputs (Sink/Source), with the former order number 6ES7-221-1BH30-0XB0 and a newer designation 6ES7-221-1BH32-0XB0 in updated catalogs. This 16-channel DI module expands the digital input capacity of a SIMATIC S7-1200 system, enabling reliable monitoring of machine states, safety interlocks, and process signals. Common applications include button panels, limit switches, proximity sensors, and photoelectric sensors in automation projects using the S7-1200 family.