Siemens 6ES7-321-1BH01-0AA0 Digital Input Module

Siemens 6ES7-321-1BH01-0AA0 is a SM321 digital input module for SIMATIC S7-300 systems, providing 16 x 24 V DC input channels that convert field signals into the PLC. In Siemens literature this model is listed as SM321 DI 16xDC24V, with the order number 6ES7 321-1BH01-0AA0, and it is used to expand discrete input capability on the S7-300 I/O bus. The 16 inputs are designed to be wired to common industrial sensors and switches—such as push-buttons, door interlocks, and proximity or limit switches—allowing the PLC to detect binary on/off states. This module is part of Siemens' SM321 family and interfaces directly with the S7-300 rack to provide scalable input density in automation panels and machinery control systems.