Allen-Bradley 1771-IT DC Input Module

The Allen-Bradley 1771-IT Fast Response DC Input Module delivers eight DC input points for a PLC-5 1771 I/O chassis, enabling rapid sensing of on/off signals from field devices. It accepts DC input signals in a 12–27 V range and draws backplane current of about 74 mA, with nominal input currents around 8 mA at 12 V and 24 mA at 24 V per channel, making it suitable for reliably reading common 12–24 V DC sensors. This module is a sink-type input unit and is typically wired in the 1771 I/O rack using the 1771-WA wiring arm (Series A) for field connections. As part of the 1771 DC I/O family, the 1771-IT is designed for fast response to discrete changes, supporting applications that require prompt digital input updates to the PLC-5 processor. Common use cases include monitoring limit switches, door interlocks, and proximity sensors on manufacturing lines, where quick state changes must be captured by the controller. With its 8-channel footprint and compatibility with standard 1771 backplanes, the 1771-IT integrates into established PLC-5 configurations to provide dependable, high-speed DC input sensing without introducing external processing.