Siemens 6ES7221-1BF22-0XA0 Programmable Logic Controller Module

Siemens 6ES7221-1BF22-0XA0 is an 8-channel digital input expansion module (EM 221) for the SIMATIC S7-200 family, designed to add eight 24 V DC inputs to a S7-200 CPU via the backplane bus. This compact I/O module extends a controller’s discrete input capability for sensor and switch monitoring in automation tasks, making it well-suited for applications such as pushbutton starts/stops, limit switches, and field-device signaling. The module’s footprint measures about 80 × 46 × 62 mm, enabling panel or cabinet installation in tight spaces, and it follows Siemens’ EM-series connection scheme for seamless integration with existing S7-200 configurations. Compatible with S7-200 CPUs that support EM 221 expansions, it provides a straightforward way to scale digital input capacity within the SIMATIC ecosystem. The 6ES7221-1BF22-0XA0 carries Siemens’ part number 6ES7221-1BF22-0XA0 and is commonly used in small-to‑mid‑scale automation setups where reliable 24 V DC input sensing is required, paired with appropriate PLC programming in the S7-200 environment.