Allen-Bradley 1771-IA PLC-5 Digital Input Module

Allen-Bradley 1771-IA PLC-5 Digital Input Module is an eight-channel digital input card for PLC-5 control systems. It accepts eight 120 V AC/DC inputs and features an operating voltage range of 87–138 V AC (47–63 Hz) or 97–138 V DC, enabling direct wiring of standard industrial sensors and switches. The module mounts in a 1771 I/O rack and uses the 1771-WA wiring arm for field connections, simplifying installation and cabling discipline. It is compatible with PLC-5 backplanes across 1771 AB through 1771-A4B chassis families, enabling deployment in a variety of rack configurations. In operation, the eight discrete input channels report their on/off state to the PLC-5 processor, supporting eight-point monitoring of field signals within automation sequences. The 1771-IA family also includes variants such as 1771-IA/C (Series C); all maintain eight input channels on 120 V AC/DC, preserving compatibility with standard PLC-5 I/O practices.