Siemens 6ES7 321-1FF01-0AA0 Digital Input Module

Siemens 6ES7 321-1FF01-0AA0 is the SIMATIC S7-300 digital input module (SM321) that provides eight isolated inputs for AC signals, designed to accept 120 to 230 V AC. This 8 DI module is built to read external field signals into the PLC while isolating the controller from process wiring, a key protection feature in industrial environments. The unit carries the order number 6ES7 321-1FF01-0AA0 and is cataloged as SM321 with 8 inputs rated for AC 120/230 V, isolated, and it uses a 20-pin connector for field wiring, enabling straightforward integration into an S7-300 rack with other SM321 variants. As part of the SM321 family, it is a discrete I/O option for Siemens SIMATIC S7-300 systems, commonly employed to interface sensors and other AC-driven devices that provide on/off signals to the PLC.