Overview
The Allen-Bradley 1785-L60B /C is a PLC-5/60 enhanced processor module from the Rockwell Automation Classic PLC-5 family, built for medium-to-large discrete and process control applications. The 1785-L60B is a PLC5 controller compatible for use in medium to large scale applications as it supports up to 64K Words of controller memory, capable of handling up to 3072 input and output signals or 3072 input and 3072 output in complimentary mode. This Series C unit is a like-for-like replacement for existing PLC-5/60 chassis installations, helping maintenance teams protect uptime on legacy lines without re-engineering the control system. Life cycle status: END OF LIFE – Discontinued December 31, 2015, which makes verified used inventory the practical sourcing path.
Key Features
- 64K word battery-backed SRAM user memory for large ladder programs
- Four DH+/Remote I/O channels (adapter or scanner) and one serial port configurable for RS-232, RS-423 and RS-422A
- Supported protocols: DF1, ASCII, Data Highway Plus (DH+), and Remote I/O (RIO)
- Three I/O hardware-addressing modes: 2-slot, 1-slot, and half-slot for mixing 8-, 16- and 32-point modules
- UL, C-TICK, CE, and CSA certified for global plant deployments
Technical Specifications
Below are the verified specs for the Allen-Bradley 1785-L60B PLC-5/60 processor module.
Typical Applications
The 1785-L60B is widely deployed across discrete manufacturing, automotive body and paint shops, water/wastewater, pulp & paper, and process plants where legacy PLC-5 racks with Data Highway Plus and Remote I/O networks remain in service. It is well-suited to systems that distribute control across many chassis — supporting up to 93 total I/O chassis (92 remote + 1 local) and up to 24 I/O racks — making it a strong fit for centralized control of large machine lines and remote I/O drops.
Compatibility & Replacements
The module installs in a standard 1771 PLC-5 chassis and programs with RSLogix 5 / PLC-5 programming software. Compatible memory backup modules are 1785-ME16 (16K Words), 1785-ME32 (32K Words), 1785-ME64 (64K Words) and 1785-ME100 (100K Words). The 1785-L60B uses an internal battery, catalog number 1770-XYC, which will completely discharge 30 days after initial activation of the BATT LED — plan replacement accordingly. For upgrade paths, Rockwell directs users to ControlLogix (1756-L7x / 1756-L8x) platforms; for direct in-kind replacement of an existing PLC-5/60, the 1785-L60B /C remains the recommended drop-in.
