Allen-Bradley 1756-L55M14 Controller Processor

The Allen-Bradley 1756-L55M14 functions as a high-performance central processing unit within the ControlLogix 5555 series. This module provides a substantial 3.5 megabytes of dedicated user memory for complex logic and data storage. Additionally, it reserves 208 kilobytes of specialized memory for managing high-speed I/O operations. These specifications enable the controller to handle demanding industrial automation sequences with high precision. Users must utilize an external battery or backup system because this model lacks built-in nonvolatile storage. Consequently, the 1756-BA1 lithium battery remains essential for maintaining program data during power cycles.

Network Versatility and Redundancy

This processor excels in diverse networking environments through its broad communication protocol support. It integrates seamlessly with established industrial networks such as EtherNet/IP, ControlNet, and DeviceNet. Furthermore, the unit facilitates legacy data exchange via Data Highway Plus (DH+) and Universal Remote I/O. For specialized applications, it supports Modbus integration through custom ladder routines and high-speed SynchLink synchronization. Engineers often deploy this module in redundant configurations for mission-critical processes. In such cases, the secondary chassis must house an identical processor to ensure flawless failover performance.

Electrical and Physical Specifications

• Backplane Current (5.1V DC): 1.25 Amps
• Backplane Current (24V DC): 0.14 Amps
• Power Dissipation: 5.7 Watts
• Thermal Output: 19.4 BTU per hour
• Isolation Voltage: 30V Continuous (tested at 707V DC)
• Operating Temperature: 0 to 60°C (32 to 140°F)
• Vibration Resistance: 2 g at 10 to 500 Hz
• Physical Weight: 0.36 kg (12.8 oz)

Rugged Industrial Design

The 1756-L55M14 features an open-style enclosure designed for direct installation into any standard 1756 ControlLogix chassis. It demonstrates high electromagnetic compatibility with a conducted RF immunity of 10V rms. Moreover, the hardware withstands operational shocks up to 30 g to ensure durability on the factory floor. The module operates reliably in non-condensing humidity levels ranging from 5% to 95%. This robust construction minimizes unplanned downtime in harsh manufacturing settings. Its compact single-slot design maximizes available space within the control cabinet.