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Siemens 6ES7221-1BF21-0XA0 — Digital Input Modules

Siemens 6ES7221-1BF21-0XA0 Digital Input Module, 8 DI 24V DC

MPN6ES7221-1BF21-0XA0

Siemens SIMATIC S7-200, EM221 digital input module, 6ES7221-1BF21-0XA0, 8 DI 24V DC sink/source input, for S7-22X CPU only.

$64.77Ref. price · indicative, final on quote
Siemens 6ES7221-1BF21-0XA0 datasheet (PDF)
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

6ES7221-1BF21-0XA0 — Specifications
ParameterValue
Weight0.08 kgs

Product details

8 digital inputs at 24V DC — sink/source configurable

The Siemens 6ES7221-1BF21-0XA0 is an EM221 digital input module for the SIMATIC S7-200 family, delivering 8 digital inputs at 24V DC with sink/source wiring flexibility. It is explicitly designed for S7-22X CPUs only — not compatible with the S7-21X series or later S7-1200/1500 platforms.

Sink or source — the input circuit answers both

Each of the 8 inputs accepts either sinking (PNP sensor) or sourcing (NPN sensor) field wiring without jumper changes. The input common is internally referenced to 24V DC; the module reads a logic 1 when the field device pulls the input to 0V (sink) or applies 24V (source) relative to the common. This eliminates the need for separate modules when mixing sensor types on the same rack.

Frequently asked questions

Is 6ES7221-1BF21-0XA0 compatible with Siemens S7-200 CPU 222?

Yes. The module is designed for S7-22X CPUs, which includes the CPU 222, CPU 224, and CPU 226. It connects via the expansion bus ribbon cable on the right side of the CPU. It will not work with S7-21X CPUs or any later S7-1200/1500 series.

Does 6ES7221-1BF21-0XA0 have sink or source inputs?

Both. The 8 digital inputs are configurable as sink or source — they accept 24V DC signals from either PNP (sourcing) or NPN (sinking) sensors without hardware changes. The input common is referenced to 24V DC.

Can 6ES7221-1BF21-0XA0 be used with 24V AC input?

No. The module is rated for 24V DC only. Applying 24V AC will not produce a reliable logic state and may damage the input circuitry. Use a DC sensor or a separate rectifier if AC field signals must be read.

MPN
6ES7221-1BF21-0XA0