The Siemens 6ES7221-1BF22-0XA8 is a spare-part digital input module from the SIMATIC S7-200 CN family, specifically the EM 221. It provides 8 digital inputs rated for 24 V DC, with a sinking-sourcing configuration. This module is designed exclusively for S7-22X CPUs and carries only CE approval.
The 8 digital inputs accept 24 V DC signals, with a typical '1' signal current of 4 mA. That 4 mA figure tells you the module's input impedance is around 6 kΩ — standard for S7-200 family inputs, so it will work with most 24 V DC sensors and pushbutton contacts without loading issues. The 2 W typical power loss is drawn from the backplane bus, not an external supply; keep that within the CPU's 5 V DC budget. Physical footprint: 62 mm deep, 46 mm wide, 80 mm high. That 46 mm width is the same as the S7-200 CPU itself, so it snaps onto the DIN rail alongside other S7-200 modules without overhang. The depth matches the CPU profile, meaning it won't stick out past the front of the enclosure.
Marked as a spare part and listed with a current lifecycle stage, the 6ES7221-1BF22-0XA8 is not in active new-production runs — it's a service-parts holdover for installed S7-200 CN bases. The 'spare part' tag means Siemens supports it for replacements but won't push it for new designs. Sourcing is via RFQ; we quote to order against confirmed demand.
This module snaps onto the same DIN rail as the S7-200 CPU and uses the standard S7-200 ribbon-cable bus connector. No special wiring or extra power supply needed — the 2 W backplane draw is within the CPU's capacity. The 8 inputs are grouped in a single terminal block; wire them as sinking or sourcing per the common rail connection.