Allen-Bradley 1756-L72 ControlLogix Processor 4MB

1756-L72 Logix5572 Controller for ControlLogix Platforms

Product Introduction

The 1756-L72 from Allen-Bradley represents a powerful processor module within the latest ControlLogix product family. This controller delivers substantial memory resources and advanced connectivity for demanding automation applications.

To begin with, the module provides 4 MB of user memory for logic and data storage, plus 0.98 MB of dedicated I/O memory. Consequently, it handles up to 128,000 digital I/O points and 4,000 analog I/O channels with ease. Furthermore, its processing power supports multiple programming languages, including relay ladder, structured text, function block, and sequential function charts.

Memory Architecture and Nonvolatile Storage

The 1756-L72 introduces a modern memory approach that eliminates the need for traditional batteries. Instead, it uses capacitor energy storage modules for short-term memory retention. Specifically, three versions exist: the removable 1756-ESMCAP, the 1756-ESMNSE (no WallClockTime backup), and the non-removable 1756-ESMNRM (which secures the controller by disabling USB and SD card access).

For permanent program storage, this controller ships with a 1 GB Secure Digital (SD) card, catalog number 1784-SD1. Additionally, you can upgrade to a 2 GB card (1784-SD2) if additional capacity becomes necessary. However, Rockwell Automation strongly recommends using only their approved SD cards. Using third-party cards may lead to data corruption or loss, as only Rockwell cards undergo full compatibility testing. The SD card primarily stores diagnostic data that the system writes automatically when a fault occurs, which aids in troubleshooting efforts.

Communication and Connectivity Features

A standout feature of the 1756-L72 is its built-in USB 2.0 port, which operates at full speed (12 Mbps). This port replaces the older RS-232 interface found on previous models. Therefore, programming, configuration, and online edits become simpler and more cost-effective, since expensive specialty cables are no longer required.

Moreover, this controller supports an extensive range of communication networks. For instance, it works with EtherNet/IP, ControlNet, DeviceNet, Data Highway Plus (DH+), Remote I/O, and SynchLink. It also integrates with third-party process and device networks. Meanwhile, the controller is OPC UA compliant, which significantly simplifies configuration within modern control and data networks.

Redundancy Support and Display Interface

The 1756-L72 fully supports controller redundancy when paired with an identical unit on the same ControlNet network. This capability enhances system availability for critical processes that cannot tolerate downtime.

Additionally, the front panel features a 4-character alphanumeric display that continuously shows device status, operating mode, and diagnostic information. You can change the operating mode using the supplied key, which provides a physical means of control. This module occupies just a single slot in any compatible ControlLogix chassis.

Power Ratings and Environmental Durability

Understanding the power specifications ensures proper system design. The 1756-L72 draws 5 mA at 1.2V DC and 800 mA at 5.1V DC from the backplane. Its power dissipation measures 2.5 Watts, while thermal dissipation reaches 8.5 BTU per hour. These relatively low figures allow for dense chassis configurations without excessive heat buildup.

Furthermore, this controller operates reliably across a wide temperature range. Specifically, the operating temperature spans 0 °C to 60 °C (32 °F to 140 °F), while storage temperatures range from -40 °C to 85 °C (-40 °F to 185 °F). Likewise, it withstands relative humidity from 5% to 95%, non-condensing. For shock and vibration, the module handles 30 g operating shock, 50 g non-operating shock, and 2 g vibration from 10 to 500 Hz.

Chassis Compatibility and Installation

The 1756-L72 fits into a wide variety of ControlLogix chassis. Compatible models include the 1756-A4, -A4K, -A7, -A7K, -A10, -A10K, -A13, -A13K, -A17, and -A17K. Its compact, single-slot design simplifies integration into new or existing control systems.

Moreover, the isolation voltage is rated at 30V continuous, with a type-tested dielectric strength of 500V AC for 60 seconds. The module has an open-style enclosure and weighs just 0.55 lbs (0.25 kg).

Packaging and Shipping Information

Each shipment of the 1756-L72 includes the processor module itself and a 1784-SD1 1GB SD card. Please note that the capacitor energy storage modules come pre-installed, and the key is also supplied.

We dispatch all orders via trusted global carriers, including Fedex, UPS, and DHL. The module follows the standard ControlLogix form factor and occupies one chassis slot.

Frequently Asked Questions (FAQ)

1. Does the 1756-L72 require a battery for memory backup?
No, the 1756-L72 does not use batteries. Instead, it relies on capacitor energy storage modules for short-term memory retention during power interruptions.

2. What SD card does the 1756-L72 ship with?
The controller ships with a 1784-SD1 1GB Secure Digital card. You may upgrade to the 1784-SD2 2GB card if you need additional nonvolatile storage.

3. Can the 1756-L72 support controller redundancy?
Yes, the 1756-L72 fully supports redundancy. You must pair it with an identical controller on the same ControlNet network for proper redundancy operation.

4. What communication protocols does the 1756-L72 support?
This controller supports EtherNet/IP, ControlNet, DeviceNet, Data Highway Plus, Remote I/O, SynchLink, and third-party networks. Additionally, it is OPC UA compliant.

5. How do I change the operating mode on the 1756-L72?
You can change the operating mode using the supplied key on the front panel. The 4-character display shows the current mode and status information.