The Siemens 6ES7924-0BG20-0BC0 is a connection module designed for routing digital input signals to a SIMATIC S7-300 or S7-1500 system. It provides 20 terminals in a single level, with 8 inputs each using two terminals plus two each for L+ and M. Rated for 1 A at 110 V AC, it handles the signal-level switching typical of proximity sensors, limit switches, and pushbuttons feeding into the PLC backplane. Mounting is on standard 35 mm or 15 mm DIN rail, and the module accepts stranded wire from 0.2 to 2.5 mm² via push-in terminals — no screwdriver needed for the wire entry, though a 3.5 mm blade releases the clamp. The enclosure is grey, 130 mm wide, 76 mm high, and 60 mm deep, so it occupies about the same footprint as a slimline relay bank.
This module sits between the field wiring and the front connector of the S7-300 or S7-1500 digital input module. Maximum wire length from the front connector to this module is 30 m, which gives flexibility for remote mounting in a larger cabinet. The infeed function is built in, so you can daisy-chain the L+ supply through the module without a separate terminal block. No shield connection or PE connection is provided on the module itself — signal shielding should be terminated at the sensor end or at a separate grounding rail. The module is rated for overvoltage category II and pollution degree 2, which is standard for clean, controlled environments inside an IP54 panel.