Siemens 6ES7321-1FH00-0AA0 Digital Input Output Module

Siemens 6ES7321-1FH00-0AA0 is a SIMATIC S7-300 digital input module (SM 321) with 16 isolated input channels that accept alternating current logic signals at 120/230 V. It communicates with the S7-300 backplane via a 1×20‑pole front connector, designed to simplify field wiring while providing galvanic isolation between the process signals and the backplane bus. This 16‑DI module is part of the SM 321 family and is documented for AC input voltages of 120 V or 230 V, making it suitable for expanding discrete input capability in automation tasks such as sensing switches, relays, and AC-powered sensors within Siemens PLC installations. By integrating seamlessly with SIMATIC S7-300 controllers, the 6ES7321-1FH00-0AA0 supports straightforward digital input mapping and ladder logic interfacing in industrial control environments that rely on robust, high‑voltage AC inputs in compact I/O blocks.