Product Overview

The Allen-Bradley 1756-L55M16 is a high-capacity central processing unit within the ControlLogix5555® family. Engineered for complex, large-scale automation, this controller features 7.5 MB of user memory and 208 KB of dedicated I/O memory. It utilizes a dual-processor architecture designed to maximize throughput: a primary Logix CPU focuses exclusively on executing application code and logic, while a secondary backplane CPU manages high-speed data exchanges and I/O communication.

This multitasking controller is capable of managing multiple prioritized tasks, ensuring that time-critical operations are executed with precision. It is built for seamless integration into the Logix5000 environment, providing a scalable and modular solution for industries ranging from automotive assembly to sophisticated process control.

Technical Specifications

• Manufacturer: Allen-Bradley / Rockwell Automation

• Model Number: 1756-L55M16

• Series: ControlLogix 5555

• User Memory: 7.5 MB (Data and Logic)

• I/O Memory: 208 KB

• Communication Ports: Built-in RS-232 serial port (DF1, DH-485, ASCII protocols)

• Chassis Requirements: Occupies one slot in any 1756 ControlLogix Chassis

• Current Draw: 1.25A @ 5.1V DC; 0.014A @ 24V DC

• Battery Options: 1756-BA1 or 1756-BATM (Extends memory retention)

• Programming: RSLogix 5000 / Studio 5000 Logix Designer

• Weight: 0.36 kg

• Dimensions: 3.5 x 14.0 x 14.5 cm

Advanced Network Integration

The 1756-L55M16 provides expansive connectivity options through separate communication interface modules. It supports a wide array of industrial networks, including:

• EtherNet/IP: For high-speed discrete control and enterprise-wide data sharing.

• ControlNet: For deterministic, repeatable I/O and interlocking.

• DeviceNet: For low-level device integration and sensor management.

The controller facilitates the use of "Produced/Consumed" tags, allowing real-time data sharing across multiple Logix controllers over the network backplane without additional programming overhead.

Diagnostic and Reliability Features

To minimize downtime, the 1756-L55M16 includes an integrated system fault handler that monitors for hardware and software irregularities. The front panel features a multi-color LED display that provides immediate visual feedback on the controller’s operational status and I/O communication health. Furthermore, the module supports online editing and programming, allowing engineers to modify logic without halting the industrial process.