6ES7221-3BD30-0XB0 SIMATIC S7-1200, CPU 1211C, compact CPU

The Siemens 6ES7221-3BD30-0XB0 is an SB 1221 digital input signal board from the SIMATIC S7-1200 series, engineered for high-speed 24 V DC digital signal acquisition in compact automation applications. As a signal board (SB), it plugs directly into the front of the S7-1200 CPU, adding 4 current-sourcing digital inputs without consuming additional cabinet space . This module is specifically designed for 24 V DC source-type inputs with an exceptionally high 200 kHz maximum input frequency, making it ideal for applications requiring precise counting, position detection, or high-speed signal processing that standard 20 kHz inputs cannot accommodate .