Allen-Bradley 1746-NI16I Isolated Analog Input Module

The Allen-Bradley 1746-NI16I is a 16-channel isolated analog input module for the SLC 500 family that digitizes current-loop signals from sensors and transmitters. Each of its 16 channels accepts current input in the -20 to +20 mA range, enabling bidirectional measurement of common 4-20 mA loops and providing headroom for fault conditions. The module provides galvanic isolation between the analog inputs and the backplane, rated up to 500 V AC for 1 second, helping protect the controller from surges and ground loops. Wiring is performed through two common terminals on the module, supporting consistent wiring for standard 2-wire current sensors. In operation, the NI16I presents 16 independent input values to the PLC’s I/O image (one word per channel), enabling high-density monitoring within a single module. Designed for use in a 1746 backplane chassis with SLC 500 controllers, this module is well-suited for applications such as flow meters, pressure transducers, and other analog signals that are provided as 4-20 mA current loops, particularly where channel-to-channel isolation and noise rejection are important.