Product Overview
The Allen-Bradley 1756-L81E is a ControlLogix 5580 Programmable Automation Controller (PAC) engineered for demanding industrial applications. As part of the modern ControlLogix 5580 family, this controller delivers high-speed processing, integrated communication, and robust memory—making it an ideal migration path for legacy PLC-5 or SLC 500 systems.
With 3 MB of user memory and a 2 GB non-volatile SD card (1784-SD2), the 1756-L81E handles complex control tasks with ease. It supports up to 128,000 digital I/O and 4,000 analog I/O points, ensuring scalability for large-scale operations.
Key Features
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Integrated Communication: One Ethernet port (10/100/1000 Mbps) and one USB 2.0 port (12 Mbps) for flexible connectivity.
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High Capacity: Supports up to 60 EtherNet/IP nodes and 32 tasks with 1,000 programs per task.
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User-Friendly Display: 4-character alphanumeric display for local status and diagnostics.
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Battery-Free Backup: Environmentally friendly energy storage eliminates the need for battery-backed RAM.
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Rugged Design: Open-style enclosure, operates in 0–60 °C, withstands 30G shock and 2G vibration.
Technical Specifications
| Parameter |
Value |
| Manufacturer |
Rockwell Automation |
| Part Number |
1756-L81E |
| Module Type |
ControlLogix Controller |
| User Memory |
3 MB |
| Isolation Voltage |
50 Volts Continuous |
| Power Dissipation |
6.2 Watts |
| Current Draw (5.1V) |
1.20 mA |
| Current Draw (1.2V DC) |
5.0 mA |
| Thermal Dissipation |
21.2 BTU/hr |
| Communication Interfaces |
One (1) Ethernet; One (1) USB |
| Maximum Digital I/O |
128,000 |
| Maximum Analog I/O |
4,000 |
| Enclosure |
None (Open-Style) |
Compatibility & Integration
The 1756-L81E installs into any single slot of standard ControlLogix chassis, including 1756-A4, A7, A10, A13, and A17 (Series B/C). It works with a broad range of standard power supplies (1756-PA50, PA72, PB50, PB75, etc.) and redundant power supplies (1756-PA75R, PB75R, PSCA2) for high-availability systems.
Programming is supported in the Studio 5000 environment, ensuring seamless integration into existing Rockwell Automation architectures. The controller's EtherNet/IP capability allows connection to up to 60 devices, making it suitable for distributed control networks.
Installation & Setup
Mount the 1756-L81E in any available slot of the ControlLogix chassis. Ensure proper power supply connection and grounding per the user manual. After installation, configure the controller using Studio 5000, setting the IP address and task priorities as needed. The USB port provides a convenient local programming interface, while the Ethernet port enables network-based access.
Maintenance & Reliability
With no battery to replace, the 1756-L81E reduces routine maintenance. Periodically check the ambient temperature and humidity (0–60 °C, 5–95% non-condensing) to ensure optimal performance. The controller's robust design—rated for 30G shock and 2G vibration—ensures reliable operation in harsh environments. Regular firmware updates via Studio 5000 help maintain security and functionality.
Buying Guide
When purchasing the Allen-Bradley 1756-L81E, verify that the part number matches your requirement and that the firmware version is compatible with your Studio 5000 installation. Consider the chassis type and power supply compatibility as listed above. For a reliable source, PLC Source PRO offers genuine Allen-Bradley modules with competitive pricing and fast shipping.