Siemens 6ES7 521-1BH50-0AA0 Digital Input Module

Siemens 6ES7521-1BH50-0AA0 is a 16-channel digital input module for SIMATIC S7-1500 controllers (SM 521 family). It provides 16 sourcing inputs at 24 V DC (SRC BA) and is designed to read binary field signals from devices such as switches, sensors, and proximity detectors. Each channel uses IEC 61131 input type 3, with the 16 inputs served in a single block for straightforward wiring and configuration. The module specifies an input delay of 3.2 ms, supporting deterministic timing in digital logic circuits. Front connectors—screw-terminal or Push-In variants—must be ordered separately from the module. This DI module expands the digital input capability of an S7-1500 system, enabling reliable monitoring of machine states, start/stop signals, and safety interlocks in automation tasks.