Siemens 6ES7321-1EL00-0AA0 Digital Input Module

Siemens 6ES7321-1EL00-0AA0 is the SIMATIC S7-300 digital input module SM 321, providing 32 galvanically isolated digital inputs for 120 V AC signals and a 1x40-pole terminal base for field wiring. Designed for use in SIMATIC S7-300 automation systems, this module converts AC field signals from sensors and switches into PLC-readable inputs while maintaining isolation between the field wiring and the backplane to protect the controller and improve noise immunity. With 32 channels, it expands input capacity for control cabinets and machine automation that rely on AC-powered digital signals. Siemens lists this part in Industry Mall as a spare part, confirming it as a direct replacement for SM 321 on compatible backplanes and ensuring continuity of legacy installations. The SM 321 family is characterized by robust digital input functionality in industrial environments, enabling reliable state capture for applications such as conveyor and packaging lines, packaging machinery, and general process automation where 120 VAC logic signals are used.