Product Overview

The Allen-Bradley 1756-L55M24 is a high-capacity Logix5555 controller designed for the ControlLogix platform. This module serves as the central intelligence for complex industrial automation systems, capable of managing high-speed discrete logic, motion control, and multi-disciplinary drive applications within a single integrated environment. Equipped with 3.5 MB of user memory, this unit is particularly suited for memory-intensive applications that require extensive data logging or complex instruction sets without relying on external battery backup for non-volatile storage.

The 1756-L55M24 is engineered for maximum flexibility, allowing it to occupy any available slot in a standard 1756 ControlLogix chassis. It supports true multi-processing capabilities, where multiple controllers can reside in the same chassis to segment control tasks. This processor seamlessly bridges communications across diverse industrial networks, including EtherNet/IP, ControlNet, and DeviceNet, via dedicated interface modules, making it a cornerstone for plant-wide data integration and distributed I/O management.

Technical Capabilities and Performance

This controller supports the full suite of IEC 61131-3 programming languages, including Ladder Diagram (LD), Structured Text (ST), Function Block Diagram (FBD), and Sequential Function Chart (SFC). This versatility allows engineers to select the most efficient programming method for specific tasks, from simple Boolean logic to advanced process regulation. The integrated RS-232 port facilitates local programming and diagnostics using 1756-CP3 or 1747-CP3 serial cables.

Thermal and electrical efficiency are core to the 1756-L55M24 design. The unit draws 1.25 Amps at 5.1V DC from the backplane, maintaining low power dissipation (5.7 Watts) to ensure system longevity even in high-density rack configurations. Its robust environmental ratings allow for continuous operation in ambient temperatures up to 60°C, providing reliable performance in demanding manufacturing and processing facilities.

Technical Specifications

• Manufacturer: Allen-Bradley / Rockwell Automation

• Model Number: 1756-L55M24

• Controller Type: Logix5555 Processor

• User Memory: 3.5 MB (Non-Volatile)

• Backplane Current (5.1V DC): 1.25 A

• Backplane Current (24V DC): 0.014 A

• Power Dissipation: 5.7 W

• Thermal Dissipation: 19.4 BTU/hr

• Local Communication: RS-232 Serial Port (DF1, ASCII, DH-485 protocols)

• Programming Languages: Relay Ladder, SFC, Function Block, Structured Text

• Operating Temperature: 0 to 60°C (32 to 140°F)

• Weight: 0.38 kg (0.84 lbs)

• Dimensions: 3.5 x 14.0 x 14.5 cm

Operational Features

• Hot-Swappable Functionality: Supports Insertion and Removal Under Power (RIUP), allowing for system maintenance and hardware replacement without total process interruption.

• Non-Volatile Storage: Integrated memory board technology ensures program retention without the maintenance overhead of lithium batteries.

• Modular Scalability: Easily integrates with digital, analog, and specialized I/O modules within the 1756 chassis family.

• Deterministic Performance: Optimized for high-speed RPI (Requested Packet Interval) settings to maintain precise control over motion and high-speed discrete tasks.