Overview
The Allen-Bradley 1756-L55M23 is a high-performance ControlLogix processor in the Logix 5555 family, designed for mid-range industrial automation and control applications. This single-slot module integrates 1.5MB of non-volatile backup memory for data and logic, plus 208KB of I/O memory. Built for scalability, reliability, and seamless integration with Rockwell Automation’s ControlLogix platform, the 1756-L55M23 delivers the performance controls engineers demand for manufacturing, process control, and motion coordination systems.
Key Features
- 100 MHz processor core with dual-CPU architecture (Logix CPU + backplane CPU)
- 1.5MB integrated non-volatile memory for program and data retention
- 208KB dedicated I/O memory for optimized backplane communication
- Support for 128 discrete and 128 analog I/O points
- Multi-network capability: EtherNet/IP, ControlNet, and DeviceNet
- RS-232 serial interface with DF1, DH-485, and ASCII protocol support
- Multitasking scheduling for concurrent process execution
- Integrated 1756-BA1 lithium battery backup (0.59g)
- Diagnostic LED and fault-handling routines for system visibility
- Compatible with RSLogix 5000 and Studio 5000 programming environments
Technical Specifications
Memory: 1.5MB non-volatile (data/logic) + 208KB I/O
Processor Speed: 100 MHz
I/O Support: Up to 128 discrete I/O + 128 analog I/O
Power Consumption (Backplane): 1.23–1.25A @ 5.1V DC; 0.014A @ 24V DC
Power Dissipation: 5.6–5.7W (19.1–19.4 BTU/hr)
Weight: 0.35 kg (12.5 oz)
Serial Interface: RS-232 (9-pin, DF1/DH-485/ASCII)
Communication Networks: EtherNet/IP, ControlNet, DeviceNet
Operating Temperature: 0–85°C (industrial rated)
Battery: 1756-BA1 lithium, requires periodic maintenance
Certifications: IEC 60068-2 (thermal shock, vibration, damp heat)
Mounting: Single-slot 1756 ControlLogix chassis
Typical Applications
- Discrete manufacturing with multi-axis motion coordination
- Process industries requiring real-time I/O synchronization
- Hybrid automation systems integrating legacy and modern devices
- Facility-wide networked control using EtherNet/IP or ControlNet
- Systems demanding reliable non-volatile program storage and hot-restart capability
Compatibility & Replacements
The 1756-L55M23 installs directly into any 1756 ControlLogix chassis (1756-A4, 1756-A7, 1756-A10, 1756-A13, 1756-A17). It supports expansion memory modules including the 1756-M16 (7.5MB), 1756-M22, 1756-M23, and 1756-M24. Programming is performed via RSLinx Classic or modern Studio 5000 environments using the 1756-CP3 or 1747-CP3 serial cable. Related Logix 5555 processors in this family include 1756-L55, 1756-L55M12, 1756-L55M13, 1756-L55M14, 1756-L55M16, and 1756-L55M24, allowing upgrades based on memory and I/O requirements. Operates with EtherNet/IP gateways and integrates with motion, safety, and I/O modules across the ControlLogix ecosystem.
