A Complete Guide to Allen Bradley CompactLogix PLCs

In this post, we will take a deep dive into the Rockwell Automation/Allen-Bradley 1769 and 5069 series of PLCs. In the next sections, we will learn about all of the different hardware components that make up the CompactLogix platform including

• Power Supply
• Controllers
• I/O Modules
• Communication Modules

Introduction to CompactLogix

The CompactLogix system is a modular, single-controller automation system.

In a CompactLogix system, you can have one controller, multiple I/O modules, and multiple communication modules in a bank. These features make it suitable for standalone machines and mid-sized automation systems.

Before we start looking at the components that make up the CompactLogix system, let's look at two key features that differentiate the CompactLogix system from the ControlLogix system.

CompactLogix Banks

Unlike the ControlLogix system, the CompactLogix system does not use a physical chassis. Instead, it has a sliding bus connector that allows modules to communicate over the CompactBus backplane. These connected modules form a bank.

In certain CompactLogix systems, there are some limitations to where modules can be positioned in a bank. For example, with a 1769 CompactLogix 5470 system, only four modules are allowed to the left and to the right of the power supply and the controller must be mounted on the left of the power supply. Tools like Rockwell Automation's Integrated Architecture Builder (IAB) can help you to understand and plan around these limitations.

Power Supply

The type of power supply used in a CompactLogix system depends on the series of CompactLogix controller being used.

Older 1769-L3X controllers use the 1769-PA2 power supply shown in the image below. The power supply is mounted in the middle of the bank and modules can be mounted on the left and right of the power supply. The modules in the bank are powered by the power supply through the CompactBus backplane - no additional wiring is required between the power supply and the modules in the bank.

Newer 5069 CompactLogix 5380 controllers can use any power supply that meets the system requirements. The incoming power is connected to the CompactLogix controller via removable terminal blocks and The CompactLogix 5380 controller then provides power to the other devices in the bank through removable terminal blocks.

Just like with the ControlLogix system, field devices in a CompactLogix system require a separate power supply.

CompactLogix Controllers

The main components of the 5069 and 1769 CompactLogix controllers are similar to each other (and to the ControlLogix controllers). Specifically, both series of CompactLogix controllers have;

Secure Digital (SD) Card

A Secure Digital (SD) card provides non-volatile memory for storing the controller's project.

Embedded USB Port

Both series of controllers have an embedded USB port. This USB port is used to create a temporary point-to-point connection between a controller and a programming device.

Energy Storage Module (ESM)

The embedded Energy Storage Module, also known as an ESM, provides power for the controller to retrieve its project from non-volatile memory after a power cycle or power loss.

Controller Mode Switch

A controller mode switch is used to select the operating mode of the controller.

Embedded Ethernet Switch

Both series of controllers have a 10 or 100 MB Ethernet switch built-in. This embedded switch supports a single IP address and a Device Level Ring network topology.

The 5069 CompactLogix 5380 Controller

The 5069 CompactLogix 5380 controller is an enhanced version of the 1769 CompactLogix controller. This controller includes all of the features found in the 1769 CompactLogix controllers and is expanded to include;

Scrolling Display

A scrolling four-digit display provides additional information at a glance allowing for easier diagnostics and troubleshooting of the system.

Processor and Field Power Connections

New processor and field power connections allow you to use any power supply that meets the system requirements with a CompactLogix system.

Dual Configurable Ethernet Ports

In the 5069 CompactLogix, the enhanced dual Ethernet ports support speeds of up to 1,000 MB and two unique IP addresses.

Increased Memory

The 5069 CompactLogix controllers have up to 20% more memory than 1769 CompactLogix controllers.

Increased Security

The 5069 CompactLogix controllers have improved security features. Specifically, the controllers include;

• Controller-based change detection and logging
• Digitally signed controller firmware
• Role-based access control (RBAC)

CompactLogix I/O Modules

Just like a ControlLogix system, a CompactLogix system can be extended with I/O modules. These I/O modules can be local I/O modules, mounted in the same bank as the controller that contains the module's configuration information, or distributed I/O modules, mounted in a different bank to the controller that contains the module's configuration information.

Since there are two series of CompactLogix Controllers (the older 1769 series and the more modern 5069 series), there are two series of I/O modules to discuss.

1769 I/O Modules

1769 I/O modules are compatible with the 1769 CompactLogix series of controllers. These I/O modules communicate either through a 1769 CompactLogix controller or a 1769-AENTR Ethernet communication module, which we will talk about shortly.

Both 1769 input and 1769 output modules have similar features. These features include;

Movable Bus Connector

The movable bus connector is a movable interface that connects modules together through the CompactBus backplane.

DIN Rail Latch

1769 I/O modules have a DIN rail latch, which is a movable piece of plastic to mount the I/O module on a DIN rail.

Removable Terminal Block

1769 I/O modules feature a Removable Terminal Block, also known as an RTB, that is used to connect field wiring to the I/O module. The 1769 I/O module RTBs are connected to the I/O module with two screws.

Status Indicators

1769 I/O modules are equipped with status indicators to show the health of the module and the communication status on the CompactBus.

5069 I/O Modules

5069 I/O modules are compatible with the 5069 series of CompactLogix controllers. These I/O modules communicate with either a 5069 CompactLogix controller or a 5069-AEN2T Ethernet communication module, which we will discuss shortly.

Both 5069 input and 5069 output modules have similar features. These features include;

Module Status Indicators

The module status indicators show the overall health of the module and its communication status on the bus.

Interlocking Side Pieces

Interlocking side pieces allow modules to be connected together to communicate on the bus.

Removable Terminal Blocks

The 5069 I/O modules include RTBs to connect the field wiring to the module.

I/O Status Indicators

The 5069 I/O modules include status indicators for each input or output on the module to see the state of the I/O point at a glance.

CompactLogix Communication Modules

The CompactLogix system has communication modules available that enable CompactLogix modules to communicate on EtherNet/IP networks. These communication modules are used to connect remote I/O modules to a CompactLogix system using an EtherNet/IP network.

In the rest of this section, we'll look at the features of one of the most commonly used CompactLogix communication modules, the 5069-AEN2TR EtherNet/IP communication module. The features of this communication module are comparable to other 5069 communication modules and the 1769 communication modules.

5069-AEN2TR EtherNet/IP Communication Module

The 5069-AEN2TR communication module allows CompactLogix modules to communicate on an EtherNet/IP network.

The module is equipped with five status indicators. Specifically, these indicators are;

OK

The OK indicator shows the overall health of the module. A solid green LED indicates that the module is operating normally.

SD

The SD indicator shows if the SD card is in use. A blinking green LED indicates that the module is reading from or writing to the SD card.

NET

The NET indicator shows the state of the EtherNet/IP port. A solid green LED indicates that the module has an IP address configured and at least one active connection with another device.

LINK1 and LINK2

The LINK1 and LINK2 status indicators show the status of the embedded Ethernet ports of the communication module. A flashing green LED indicates that the module is communicating through the Ethernet port.

5069-AEN2TR EtherNet/IP Communication Module

The 5069-AEN2T is very similar to the 5069-AEN2TR with the exception that it does not have the SD status indicator.

Wrap Up

In this article, we learned about the hardware components that make up the Logix 5000 CompactLogix system. Specifically, we talked about the controllers, I/O modules, and communication modules that are available to use in CompactLogix systems.

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