Siemens 6ES7421-1BL01-0AA0 SM421 Input Module

Siemens 6ES7421-1BL01-0AA0 SM421 Digital Input Module is a 32-channel digital input module for the SIMATIC S7-400 automation system. It provides 32 DI points, each accepting DC 24 V signals, and the module offers isolation between the field wiring and the backplane to improve noise immunity and safety in industrial environments. The unit consumes about 6 W of power and is designed to be mounted in an S7-400 rack alongside other SM modules. As part of the SM 421 family, this module expands digital input capacity for Siemens S7-400 installations, enabling reliable reading of 24 V DC input signals from field devices such as sensors and switches.