Allen-Bradley 1756-L55 ControlLogix Processor Module

Allen-Bradley 1756-L55 ControlLogix Processor Module is the CPU at the heart of Rockwell Automation's ControlLogix family, delivering the processing power to execute ladder logic, structured text, and function block programs inside a ControlLogix chassis over the 1756 backplane. As a Series A processor, the L55 line includes variants such as L55M12, L55M13, and L55M14, designed to work with the 1756-BA1 lithium memory battery for nonvolatile data retention (0.59 g lithium). This processor module is a discontinued component in the ControlLogix lineup, reflecting an older generation of hardware but still encountered in legacy installations. In typical applications, it coordinates inputs and outputs across I/O modules and other communications devices within the same rack, handling machine control, batch processes, conveyors, and automated sequences with deterministic execution. To deploy a complete control system, the L55 is installed in a compatible ControlLogix chassis with matching power supply and I/O modules, forming a single, coordinated controller capable of managing multiple points of digital and analog I/O along with logic and sequencing tasks.