Allen-Bradley 1785-LT3 PLC-5/12 Processor Module

The 1785-LT3 is a PLC-5/12 Processor Module engineered to direct sequential control, automated processing operations, and comprehensive factory-floor data handling. This slot-mounted hardware component installs into the left-most slot of a standard 1771 I/O chassis, executing specialized ladder logic programs to manage complex system variables. Functioning as a standalone and adapter-capable device on industrial networks, the 1785-LT3 coordinates multi-node signals and diagnostic data via built-in physical connection interfaces.

Features

• Seamless interlocking architecture designed exclusively for insertion into standard 1771 I/O chassis frames
• Integrated rear switch assembly (SW1) enabling direct manual assignment of the physical station address
• Multiple front-facing LED diagnostics providing continuous real-time verification of operational, communication, and battery conditions
• Dedicated logic capabilities that execute bit-level instructions, advanced math functions, and automated runtime troubleshooting

Applications

• Sequential manufacturing control networks
• Machine-level diagnostic and execution systems
• Distributed data acquisition nodes
• Distributed control architecture utilizing peer-to-peer communication

Technical Specifications

Connections/Interfaces

Installation Guidelines

• Chassis Positioning: Always install the processor module into the dedicated, left-most slot of the 1771 I/O backplane chassis to ensure proper logic termination.
• Keying Band Fitment: Position the hardware keying bands securely within the backplane rails between slots 40 and 42, and between slots 54 and 56 to verify correct module insertion.
• Isolation Warning: Turn off all electrical supplies feeding the local I/O chassis or memory socket before mounting the hardware or sliding an EEPROM into the slot to eliminate major diagnostic faults or data corruption.
• Ground Infrastructure: Bond a dedicated grounding electrode conductor from the I/O chassis enclosure wall star washer directly to the main plant earth ground bus to minimize industrial EMI.

Compliance and Certifications

• CSA certified
• CSA Class I, Division 2, Groups A, B, C, D
• UL listed