What this SM 321 module does in an S7-300 rack
The Siemens 6ES7322-1EH01-0AA0 is a SIMATIC S7-300 SM 321 digital output module providing 16 channels of optically isolated 120V AC outputs at 0.5A per channel, terminated through a 20-pin front connector. Each output switches 120V AC loads — solenoids, contactor coils, indicator lamps — with optical isolation between the backplane and the field side, so a short on one channel won't take down the CPU bus.
Lifecycle reality — EOL hot, plan the replacement now
Sourcing this module — availability and next steps
Because this is an EOL part, stock is finite and prices reflect scarcity — early commitment on the BOM quantity locks in supply before the channel dries up.