A Complete Guide to Allen Bradley Micro800 PLCs

Allen Bradley Micro800 PLCs are a range of small PLCs that are designed for small, standalone machines. Micro800 PLCs are at the core of Rockwell Automation’s Connected Components platform.

In this post, I’ll talk you through the main features of Micro800 PLCs and explain the different product families that are available to buy and use in your automation applications.

Before we look at the individual product families, let me introduce some of the key features of Micro800 PLCs.

Micro800 PLCs can be extended with plug-in modules that add extra functionality to PLCs. This allows Micro800 users to personalize a PLC and only pay for the functionality that they need in their application.

Micro800 PLCs are designed to be easy to work with. Each model includes an embedded USB port to easily connect to the controller and can be programmed using IEC 61131-3 standard instructions.

Micro800 PLCs also have preferred compatibility with other devices in the Connected Components platform including HMIs, safety relays, variable frequency drives, and servo drives. These devices can be combined to easily build a simple control system made of components supplied by a single manufacturer.

The Micro800 Controller Families

This image shows an overview of the Micro800 PLC families that are available to buy and use in automation applications.

In the next sections, we’ll look at the specific Micro800 PLC families to understand the features and capabilities of each PLC, starting with the Micro810.

Micro810

The Micro810 PLC is nano-PLC that can replace smart relay devices. It is equipped with;

• High current relay outputs that eliminate the need for external relays, helping customers to reduce costs and panel space.
• 8 Smart Relay Function Blocks which include Delay Off and Delay On Timers, Counters, and Time of Day, Time of Week, and Time of Year.
• Finally, it has 4 channels of embedded analog inputs which are 0 to 10 volts and 10 bit resolution.

The Micro810 PLC can be equipped with an optional LCD screen. This screen has a built-in memory backup capability so it can be used to copy programs to multiple machines.

Micro820

The Micro820 PLC is specifically designed for small, standalone machines and remote automation projects.

It features embedded Ethernet and Serial ports for communications as well as a MicroSD card slot for data logging and recipe management. It can function as an RTU also known as a remote terminal unit for remote machines with support for Modbus RTU and TCP.

The Micro820 has embedded support for 4 thermistor temperature inputs. It can also be extended by installing up to two Micro800 plug-in modules.

Finally, the Micro820 can be paired with a 3.5 inch LCD display which connects to the controller via RS232. The LCD display supports 4 or 8 lines of ASCII text and has a keypad with programmable function keys.

The LCD is rated IP65 for mounting through a cabinet door when used as a simple operator interface.The LCD can also serve as a configuration device for the controller and supports DIN rail mounting next to the controller.

The LCD has a system menu available in several languages for directly viewing and editing program variables and the ability to set the controller's Ethernet address.

Micro850

Micro850 controllers are designed for larger stand-alone machine control applications that require flexible communications and greater I/O capabilities.

The Ethernet port supports simultaneous use of;

• EtherNet/IP protocol for faster and simpler connection to Rockwell Automation products like HMIs, drives, etc, and
• Modbus TCP protocol for communication to a wide range of 3rd party devices

The Micro850 also supports up to 4 Expansion I/O modules which snap firmly on right side of the controller. The expansion I/O modules are equipped with removable terminal blocks for easy installation.

All in, the Micro850 supports up to a total of 132 on-board, plug-in and expansion digital IO.

Micro870

The Micro870 is the latest addition to the Micro800 line up.

It features double the program capacity of a Micro850 controller and support for even more IO modules.

Micro870 controllers can be used for demanding standalone machine applications and small process skids.

Now that you know what PLCs make up the Micro800 family, let’s take a quick look at the accessories that can be used to customize them.

Micro800 Accessories

Plug-In Modules

The most important accessory for Micro800 PLCs are the plug-in modules which allow you to extend the functionality of a controller without increasing its footprint.

There is a wide range of plug-in modules available to increase the I/O capacity of a controller and to add new functionality like DeviceNet communication and motion control.

This table shows the complete range of Micro800 plug-in modules that are available to use.

Expansion I/O Modules

As well as plug-in modules, the Micro850 and Micro870 controllers support Expansion I/O Modules.

These are more advanced, higher-density I/O modules that clip firmly to the side of the controller to add additional I/O capacity to a Micro850 or Micro870 controller.

The table below shows a complete list of Expansion I/O modules that are available for Micro850 and Micro870 controllers.

Micro800 Catalog Numbers

The image shows how you can build a Micro800 catalog number using the Bulletin Number, Product Family, I/O Count and Controller Details.

This sheet will help you quickly understand what options are available for the various Micro800 product families.

And the following tables outline the different options that are available for each Micro800 Product Family.

Micro810 Controller Catalogs

Micro820 Controller Catalogs

Micro850 Controller Catalogs

Micro870 Controller Catalogs

PLC Selection

As you can see, there are many different Micro800 product families to choose from. This table may help you select the right Micro800 PLC for your project.

Wrap Up

In this post, I have introduced Allen Bradley’s Micro800 range of PLCs. These PLCs are at the heart of Rockwell Automation’s Connected Components platform and provide a range of cost-effective PLCs for micro-control applications like small, standalone machines.

To learn more about Micro800 PLCs and find the latest information on catalog numbers, check out the Micro800™ Programmable Controller Family Selection Guide, publication 2080-SG001.