Allen-Bradley 1785-L20B

Allen-Bradley 1785-L20B | PLC-5/20 Processor Module with 24K Words Memory for Legacy Automation Systems

Overview

The Allen-Bradley 1785-L20B is a PLC-5/20 processor module from the PLC-5 Classic platform, offering 24K words of user memory and a rich 57-instruction set. Designed for use in large and mid-range automation systems, it supports distributed control and I/O networks through classic Allen-Bradley communication protocols. The 1785-L20B is ideal for maintaining or upgrading legacy systems in industrial environments.

Key Features

• Processor Type: PLC-5/20

• User Memory: 24K words

• Instruction Set: 57 standard instructions

• Communication: RS-232 serial port

• Chassis Compatibility: 1771 I/O chassis

• Programming Software: RSLogix 5 or AI Series

• Mounting: Installed in leftmost slot of the 1771 chassis

• Battery-Backed Memory: Yes (battery included)

Technical Specifications

• Catalog Number: 1785-L20B

• Series: PLC-5 Classic

• Input Power (Backplane): Supplied via 1771 chassis

• Memory Type: RAM with battery backup

• Communication Port: RS-232 (DF1 Protocol)

• Operating Temp: 0°C to 60°C

• Certifications: UL, CE, CSA

• Dimensions (HxWxD): Approx. 230 x 50 x 200 mm

Applications

• Legacy industrial automation systems

• Process control in manufacturing and utilities

• Plant-wide distributed I/O networks

• Upgrading or maintaining PLC-5 installations

• Mission-critical systems requiring long lifecycle support

Why Choose the 1785-L20B PLC-5/20?

• Long-Term Reliability: Proven performance in legacy environments

• Expandable: Compatible with 1771 I/O systems

• Rockwell Software Support: Configurable with RSLogix 5

• Low Risk Migration: Continue operations while planning upgrades

• Industrial Standard: Widely adopted in legacy Allen-Bradley setups

Order Now

The Allen-Bradley 1785-L20B is available and ready for worldwide shipping.