S7-300 Rack Fit — 16 DI, Isolated, Source Input
The 6ES7321-1BH50-0AA0 is a SIMATIC S7-300 SM 321 digital input module delivering 16 isolated inputs at 24 V DC, source-input type, drawing 7 mA typical per channel at signal "1". It occupies one slot on the S7-300 DIN rail backplane — 40 mm wide, 125 mm high, 120 mm deep — and requires a 20-pin front connector for field wiring. The input filters are fixed (not parameterizable): 1.2 ms to 4.8 ms on both rising and falling edges, so the module responds to fast sensor edges within that window.
Isolation, Diagnostics, and Sensor Compatibility
Channel-to-backplane isolation uses optocouplers, tested at 500 V DC — the 16 inputs share a common group, so all channels in the group must reference the same field ground. No diagnostic alarm, no hardware interrupt, no parameterizable alarms — this is a basic-input module for straightforward 24 V DC sensing where you don't need per-channel fault reporting. Accepts 2-wire proximity sensors; the permissible quiescent current is 1.5 mA max, so a sensor's dark current must stay below that to guarantee a clean "0" signal.