1756-L1 | Allen-Bradley | ControlLogix Logix5550 Processor Module

Product Overview

The Allen-Bradley 1756-L1 serves as a foundational computing engine for the ControlLogix 5550 series. This processor module executes high-speed control instructions and manages I/O data across the 1756 backplane. It provides 64 KB of user memory, specifically designed for localized machine control or distributed control nodes within a larger architecture. We supply this unit in 100% Brand New, original factory condition, ensuring your legacy systems benefit from zero-hour hardware and factory-sealed integrity.

Technical Specifications

Engineering Advantages

• Deterministic Instruction Execution: The 1756-L1 utilizes a dedicated multitasking operating system. It prioritizes critical control loops and ensures consistent scan times, which prevents jitter in sensitive motion or timing applications.

• RS-232 Versatility: The integrated RS-232 port supports multiple protocols, including DF1, DH-485, and ASCII. This allows direct connection to HMIs, weigh scales, or legacy SLC/PLC-5 systems using the 1756-CP3 serial cable without requiring additional communication cards.

• Non-Volatile Memory Expansion: The processor features a physical slot for 1756-M series memory modules. Installing a 1756-M1 or M2 module protects your application code against battery failure and facilitates rapid program cloning across multiple machines.

• Chassis-Based Scalability: The module fits into any slot of a ControlLogix chassis. This allows engineers to place multiple 1756-L1 processors in a single rack to segment control tasks—such as dedicated safety monitoring or complex data logging—independently of the main process controller.

• Rigid Thermal Management: The open-style enclosure design optimizes natural convection airflow. It dissipates only 4.1 Watts of power, preventing localized hotspots within the chassis and extending the life of adjacent I/O modules in high-density installations.

FAQs

• How do I maintain the program memory during power loss?

  The 1756-L1 requires a lithium battery (1756-BA1 or 1756-BA2). We recommend installing a Brand New battery alongside this processor to ensure long-term data retention. Additionally, use a memory module (1756-M1/M2/M3) for non-volatile storage.

• Can this processor communicate over Ethernet?

  The 1756-L1 does not have an onboard Ethernet port. To connect to an EtherNet/IP network, you must install a communication bridge module, such as a 1756-EN2T or 1756-ENBT, in the same chassis.

• What is the maximum number of I/O points the 1756-L1 can handle?

  The 64 KB memory limit defines the complexity of the code rather than a strict I/O count. However, for large-scale distributed I/O systems, consider upgrading to a 1756-L55 or L61 if your application program exceeds the 64 KB boundary.

• Is this a refurbished or used unit?

  No. We guarantee that this 1756-L1 is 100% Brand New. It ships in the original Allen-Bradley packaging with factory seals intact, protecting you from the reliability risks associated with surplus or used hardware.