What this module is
The Siemens 6AG1321-1FF10-7AA0 is a digital input module with 8 AC inputs rated for 120/230 VAC. It operates from -40 to 70 °C, drawing 4.9 W from the backplane, and needs a 40-pin front connector.
Key ratings and what they mean for fit
The module operates -40 to 70 °C with input thresholds 0-40 V for signal '0' and 79-264 V for signal '1', transition time max 25 ms, and each input isolated per group of 1 via optocoupler.
Where it fits
This module expands on the DIN rail via a 40-pin connector; the controller auto-assigns I/O address. At 40 mm wide, it occupies one slot with a green LED per channel for loop check.