Siemens 6ES7321-1BH02-0AA0 Digital Input Module

Siemens 6ES7321-1BH02-0AA0 is a SIMATIC S7-300 digital input module (SM 321) that provides 16 isolated DC 24 V inputs in a single 20‑pole front connector, designed to expand a PLC’s ability to read 24 V DC signals from sensors and switches. The inputs are galvanically isolated from the backplane, enabling safe wiring of field devices without affecting the CPU, and the module conforms to the S7-300 I/O topology with a 20‑pole interface for straightforward backplane mounting. Each of the 16 channels accepts 24 V DC logic signals, making it suitable for common factory automation tasks such as reading pushbuttons, limit switches, photoelectric sensors, and other 24 V logic devices; as an SM 321 component it functions as an expansion or replacement in existing SIMATIC S7-300 installations and is compatible with standard S7-300 CPU systems.