Allen-Bradley PLC Families Explained: Micro800, CompactLogix & ControlLogix

Rockwell Automation makes a lot of different types of PLCs, including Micro800 PLCs, CompactLogix PLCs, and ControlLogix PLCs. Within these PLC families, there are different variants to consider, and then there are older PLC families that are discontinued but still deployed in the field.

In this video, I'll clear up the differences between all of these PLC families by walking you through the Allen-Bradley PLC families, talking about the main features of each PLC family, and explaining the positioning of each controller family relative to the others.

By the end of the video, you'll be able to look at any Allen-Bradley controller and know roughly where it sits in the product lineup and understand its capabilities.

Let's start with an overview of the PLC families.

The Allen-Bradley PLC Families

The current Allen-Bradley PLC families in the Rockwell Automation controller portfolio are the Micro800 family and the Logix 5000 family.

The Micro800 family is a range of low-cost controllers designed to control simple machines.

The Logix 5000 family includes CompactLogix and ControlLogix controllers.

CompactLogix controllers are designed to control medium-sized machines and process skids.

ControlLogix controllers are advanced controllers designed to control production lines or large processes.

You may also hear about MicroLogix, SLC, and PLC-5 PLCs. These are older PLC families that are largely discontinued but still have a huge install base in the field. At the end of the video, I’ll explain the positioning of these older PLC families relative to the modern Allen-Bradley PLC families.

Now let’s look at these PLC families in more detail, starting with the Logix 5000 family.

The Logix 5000 Family

There are four key features to know about the Logix 5000 family of PLCs:

Integrated Architecture

Logix 5000 controllers are at the core of Rockwell's Integrated Architecture portfolio, which is a range of tightly integrated control products including controllers, I/O systems, servo drives, variable speed drives, and HMIs.

Scalability

The Logix 5000 family of PLCs is designed to be scalable. This means that there are Logix 5000 controllers that are suitable for everything from small machines and process skids up to very large production lines with tens of thousands of I/O points and many axes of motion and all of these PLCs are programmed with the same software, Studio 5000 Logix Designer.

Multi-discipline control.

One controller can handle discrete, process, motion, and safety control.

EtherNet/IP.

Logix 5000 controllers use EtherNet/IP, a real-time control network built on standard, unmodified Ethernet and Internet Protocol. Because it's IT-ready, data can be sent directly to IT networks for collection and analysis.

The CompactLogix System

CompactLogix is a modular PLC system that is positioned in between the Micro800 family and the ControlLogix system.

Right now, there are three generations of CompactLogix controllers available on the market. They are the 1769 CompactLogix 5370, the 5069 CompactLogix 5380, and the 5034 CompactLogix 5390 controllers.

Each new generation of CompactLogix PLC unlocks faster scan times and improved capabilities.

Regardless of the generation, CompactLogix PLCs have some features in common:

First, every CompactLogix PLC uses a rackless system to connect IO modules. This means that a CompactLogix PLC doesn't use a physical chassis to connect modules. Instead, modules connect to each other using a connector on each module. Each generation of CompactLogix PLC uses different IO modules.

EtherNet/IP communication is embedded in the controller, with the ports located at the bottom of the controller. Projects can be downloaded over the Ethernet port or the embedded USB port.

CompactLogix controllers have an SD card behind a small door on the front. It's used to back up the control program, so if a controller fails, you can move the SD card to a new controller and recover quickly.

CompactLogix products start with 1769, 5069, or 5034.

CompactLogix Variants

Within the different CompactLogix families, there are different controllers with different capabilities.

The different controllers within a family have different amounts of memory available, support different numbers of IO Modules, and can communicate with a different number of devices over an EtherNet/IP network.

In the 1769 and 5069 CompactLogix families, there are also variations of controllers that have motion and safety capabilities. Safety rated CompactLogix controllers are called Compact GuardLogix controllers.

In the 5034 range of CompactLogix controllers, all controllers support safety and motion, so the number of controller variations is dramatically reduced.

When it comes to selecting a CompactLogix PLC for an application, the CompactLogix Selection Guide is a great help.

The ControlLogix System

ControlLogix is a chassis-based system, which means that a physical chassis is used to connect the modules in the system. Power is provided to the modules through a power supply that connects to the chassis.

A ControlLogix controller can be installed in any slot, and you can install multiple controllers in a single chassis.

Modern controllers have EtherNet/IP ports built in, but you can also add additional networks to the system using dedicated communication modules.

To add IO points to the system, IO modules can be installed in the chassis.

The ControlLogix system also supports specialty modules that provide advanced features like redundancy for critical applications or model predictive control for advanced tuning of process applications.

Just like CompactLogix, there are several generations of ControlLogix controllers available today. They are the 5570, 5580, and 5590 controllers. Each generation has introduced faster scan times, better networking capability, and improved security.

Once again, the ControlLogix selection guide published by Rockwell Automation is a very useful asset when trying to determine which ControlLogix controller is right for a given application.

The Micro800 Family

At the lower end of the Allen Bradley controller portfolio is the Micro800 family. These are low-cost controllers designed for small, standalone machines. They come in a range of form factors with different combinations of embedded I/O, so you can pick one that fits a project.

These PLCs can be extended with plug-in modules that add capabilities to a controller without increasing its footprint.

Larger Micro800 controllers support expansion IO which increases the IO capacity of a controller through IO modules that clip to the side of the controller.

When it comes to programming Micro800 PLCs, there are two options.

Connected Components Workbench is the original development environment that was developed for Micro800 PLCs. It is free to download and use but, frankly, is quite slow and unstable.

In 2026, Rockwell Automation released FactoryTalk Design Workbench as a replacement for Connected Components Workbench. This is an improved development environment for Micro800 PLCs that is built with modern technology and is aligned with other Rockwell Automation software.

Positioning the Controllers

As you have seen, the Allen Bradley PLC family has a solution for most applications.

The Micro800 family of PLCs is well suited for small, standalone machines.

The CompactLogix family of PLCs is suited for medium-sized machines that may need motion and integrated safety as well as process skids.

Finally, the ControlLogix family of PLCs is suited to large, complex applications that may require specialty functionality like redundancy.

Older Controller Platforms

Finally, when working in the field, you will still come across older Allen-Bradley PLC families. The older families that you may encounter are:

PLC-5 PLCs which were introduced in the mid-1980s. These PLCs are discontinued and PLC-5 applications should be migrated to ControlLogix PLCs.

SLC, or Small Logic Controllers, which covered medium sized applications that the CompactLogix covers today. Again, these PLCs are discontinued and SLC PLC systems should be migrated to CompactLogix.

MicroLogix PLCs which were the previous generation of micro controllers. Some of the MicroLogix PLCs are not yet discontinued and are still popular with OEMs today but for new projects the recommendation is to use Micro800 PLCs.

Wrap Up

Now you understand the Allen-Bradley controller portfolio, including the Micro800 and Logix 5000 families, how the CompactLogix and ControlLogix systems are built, and how controllers are position relative to each other.