Allen-Bradley 1746-IV16 USNT Digital Input Module

The Allen-Bradley 1746-IV16 USNT is a 16-channel digital input module for the SLC 500 I/O bus, designed to read 16 discrete DC sensor signals into a PLC. It accepts 10–30 V DC input levels and provides 16 isolated field inputs, with 500 V DC isolation between the field circuits and the backplane to help protect the controller from voltage transients. This module plugs into a 1746 backplane rack and occupies a single I/O slot, enabling straightforward mapping of 16 devices such as pushbuttons, limit switches, or proximity sensors to the CPU via the 1746 I/O bus. As part of the SLC 500 family, the 1746-IV16 integrates with standard Rockwell Automation processors and supports typical SLC 500 scan operations, delivering reliable, deterministic input status to logic routines and control sequences. The product designation 1746-IV16 identifies a sixteen-point, 24 VDC input module within Allen-Bradley’s legacy automation line, making it a common choice for general-purpose DC input applications in manufacturing environments that rely on legacy SLC 500 hardware. This configuration is compatible with existing 1746 I/O adapters and enclosures, providing a compact solution for expanding a controller’s sensing capabilities without upgrading the entire control system.