Allen-Bradley 1756-L81E ControlLogix Processor Overview

The Allen-Bradley 1756-L81E is a ControlLogix 5580 processor. This controller features 3 MB of user memory for programs and data. The 1756-L81E includes an embedded Ethernet port and a USB 2.0 port. This controller supports 60 EtherNet/IP devices simultaneously. It handles 32 tasks with up to 1000 programs per task. The processor displays status on a 4-character alpha/numeric display. Consequently, the 1756-L81E serves as an excellent migration platform for legacy PLC-5 and SLC 500 systems.

Memory & I/O Capacity

The Allen-Bradley 1756-L81E offers substantial I/O capacity for demanding applications. Maximum discrete I/O reaches 128,000 points for both inputs and outputs. Maximum analog I/O reaches 4,000 points. The controller ships with a 2 GB non-volatile memory via a 1784-SD2 Secure Digital (SD) card. This controller eliminates the need for a battery to back up RAM. Instead, it uses an environmentally friendly energy storage solution. Therefore, the 1756-L81E requires no battery replacement maintenance.

Communication Interfaces

The Allen-Bradley 1756-L81E provides modern connectivity options. The embedded Ethernet port operates at 10 Mbps, 100 Mbps, or 1000 Mbps speeds. This port supports up to 60 EtherNet/IP nodes for device connectivity. The USB 2.0 port operates at 12 Mbps for programming and firmware updates. Therefore, the 1756-L81E offers flexible communication for various applications.

Power & Current Specifications

The Allen-Bradley 1756-L81E draws power from the ControlLogix chassis backplane. Current draw at 5.1 Volts DC is 1.20 Amperes (1,200 mA). Current draw at 1.2 Volts DC is 5.0 Amperes (5,000 mA). Power dissipation measures 6.2 Watts . Thermal dissipation is 21.2 BTU per hour . Isolation voltage is 50 Volts continuous . Therefore, ensure your power supply has sufficient capacity for the 1756-L81E .

Compatible Hardware

The Allen-Bradley 1756-L81E fits into various ControlLogix chassis. Compatible chassis include 1756-A4, 1756-A4K, 1756-A7, 1756-A7K, 1756-A10, 1756-A10K, 1756-A13, 1756-A13K, 1756-A17, and 1756-A17K Series B and Series C. The controller supports standard power supplies such as 1756-PA50, 1756-PA72, 1756-PA72K, 1756-PA75, 1756-PA75K, 1756-PB50, 1756-PB72, 1756-PB72K, 1756-PB75, 1756-PB75K, 1756-PH75, and 1756-PC75. For redundant systems, use power supplies like 1756-PA75R, 1756-PA75RK, 1756-PB75R, 1756-PB75RK, 1756-PSCA2, and 1756-PSCA2K. The 1756-L81E can operate in both simplex and redundant (high-availability) configurations.

Environmental & Certification Specifications

The Allen-Bradley 1756-L81E operates reliably in industrial environments. Operating temperature ranges from 0°C to 60°C (32°F to 140°F) . Ambient humidity tolerance spans 5% to 95% without condensation . The controller withstands 30G shock for rugged durability. Vibration tolerance reaches 2G at 10-500Hz . The 1756-L81E carries IECEx, CSA, and c-UL-us certifications . It has a T4 temperature code (ATEX, IECEx, and North America). Emission rating meets IEC 61000-6-4 standards. The enclosure type is open-style (no IP rating).

Software Compatibility

The Allen-Bradley 1756-L81E runs on the Studio 5000 Automation Engineering & Design Environment. This modern software platform provides integrated programming and configuration. Therefore, the 1756-L81E supports the latest Logix 5580 features.

Key Features & Benefits

• 3 MB user memory – The 1756-L81E stores large programs and data tables.

• Embedded Gigabit Ethernet – Supports 10/100/1000 Mbps speeds for fast communication.

• USB 2.0 port – Provides convenient programming and firmware update access.

• No battery required – The 1756-L81E uses an energy storage solution instead of batteries.

• High I/O capacity – Handles 128,000 discrete I/O and 4,000 analog I/O.

• Redundant capable – Supports high-availability configurations for critical processes.

Installation Guidelines

Follow these steps to install the Allen-Bradley 1756-L81E correctly. First, power down the ControlLogix chassis completely. Second, select any available slot in the chassis (the 1756-L81E occupies a single slot). Third, align the processor with the card guides in the chassis. Fourth, push the 1756-L81E firmly into the backplane connector until fully seated. Fifth, secure the module with the retaining screws at top and bottom. Finally, apply power and connect programming software via Ethernet or USB.

Configure the Ethernet port with an IP address using Studio 5000 software. The 1756-L81E automatically detects network speed and duplex settings.

Package Contents

Your shipment includes the following items:

• 1 x Allen-Bradley 1756-L81E ControlLogix 5580 processor

• 1 x 1784-SD2 2GB Secure Digital memory card

• 1 x Installation instructions manual

No programming software is included with the 1756-L81E . Therefore, you must purchase Studio 5000 separately. No communication cables are provided.

Frequently Asked Questions (FAQ)

1. What is the user memory size of the 1756-L81E?
The Allen-Bradley 1756-L81E provides 3 MB of user memory for programs and data. This suits small to medium-sized control applications.

2. Does this controller require a battery?
No. The 1756-L81E eliminates the battery requirement. It uses an environmentally friendly energy storage solution for RAM backup.

3. What is the maximum number of EtherNet/IP devices supported?
The 1756-L81E supports up to 60 EtherNet/IP devices simultaneously. This includes I/O adapters and other communication nodes.

4. Can I use this processor in a redundant system?
Yes. The 1756-L81E supports redundant (high-availability) configurations. Use the listed redundant power supplies for these applications.

5. What software do I need to program the 1756-L81E?
The Allen-Bradley 1756-L81E requires Studio 5000 Automation Engineering & Design Environment. This software supports all Logix 5580 features.

Why Choose the Allen-Bradley 1756-L81E?

This ControlLogix 5580 processor delivers powerful control for modern industrial applications. For starters, the Allen-Bradley 1756-L81E provides 3 MB of user memory for complex programs and large data tables. It handles up to 128,000 discrete I/O points and 4,000 analog I/O channels. The embedded Gigabit Ethernet port supports 10/100/1000 Mbps speeds for fast communication with up to 60 EtherNet/IP devices. The USB 2.0 port offers convenient programming access. The 1756-L81E eliminates the need for battery backup, using an environmentally friendly energy storage solution instead. The controller fits any slot in standard ControlLogix chassis and supports both simplex and redundant configurations. Operating temperature from 0°C to 60°C suits most industrial environments. The processor withstands 30G shock and 2G vibration for rugged durability. International certifications include IECEx, CSA, and c-UL-us. Most importantly, the 1756-L81E provides a clear migration path from legacy PLC-5 and SLC 500 systems to the modern Logix 5580 platform.

Order the Allen-Bradley 1756-L81E today for your ControlLogix control needs. Specifically, this processor is perfect for mid-sized applications, legacy controller migrations, and systems requiring EtherNet/IP communication with up to 60 devices.