This post introduces you to the key features of the Micro810, Micro820, Micro830, Micro850, and Micro870 Allen-Bradley Micro800 PLCs and explains the difference between each model.
If you have been reading my content for a while, you probably know that I am a big fan of Allen-Bradley Micro800 PLCs as an affordable PLC to learn PLC programming with. That's one of the reasons why I use it as the PLC system for PLC Bootcamp, my free course that teaches you how to write, test, and simulate your first PLC program using free tools.
The Micro800 PLC system is a family of related PLCs that are part of Allen-Bradley's Connected Components Platform. Each Micro800 PLC model has different features and functions that make it more or less suitable for specific applications. In this post, I will explain the key features of the Micro810, Micro820, Micro830, Micro850, and Micro870 PLCs and give recommendations on which models I think are most suited to learn PLC programming with.
As you may have guessed from the naming, a higher number generally indicates more performance and features as well as a greater memory and I/O capacity. This is highlighted in the image below that shows the positioning of each Micro800 PLC relative to the other PLCs in the family.
Despite the fact that there are differences between the features available in each Micro800 PLC model, all of the Micro800 PLCs are programmed with Connected Components Workbench, the free development environment from Rockwell Automation that is used to program, configure, and monitor devices in the Connected Components Platform.
Let's start by looking at the black sheep of the Micro800 PLC family: the Micro810 PLC.
Unlike the other PLCs in the Micro800 family, the Micro810 PLC could be described as a nano-PLC or even a smart relay.
The Micro810 occupies a very small footprint and is equipped with:
The Micro810 PLC can be equipped with an optional LCD screen. As well as providing a simple graphical interface for a Micro810 PLC, the LCD screen has a memory backup capability that allows cloning. Cloning is the copying of one standard project to many controllers.
Although the Micro810 is a great nano-controller, it does not have the features or functionality to control an automated process. I do not recommend that anyone uses this PLC to learn PLC programming or to control even a simple standalone machine.
The Micro820 is the smallest PLC in the Micro800 family if you exclude the Micro810. The Micro820 is designed to control small, standalone machines and to control remote applications.
The Micro820 features 20 I/O points including 4 thermistor temperature inputs, an embedded Ethernet port, serial port, and a MicroSD card slot which can be used for data logging and recipe management. If the base functionality of the Micro820 is not enough for an application, it can be extended using up to two plug-in modules.
The Micro820 can be used with an optional Allen-Bradley Micro800 3.5 inch LCD display, which connects to the controller via RS232. This display supports 4 or 8 lines of ASCII text and has a keypad with programmable function keys. The display has a system menu that can be used to set the IP address of the controller and to view and edit program variables.
The LCD display can be used as a configuration device for the controller or a simple operator interface. When being used as a configuration device, it can be DIN rail mounted next to the controller in the control panel. When being used as an operator interface it can be mounted through a cabinet door safely thanks to its IP65 rating.
Finally, the LCD display has a USB programming port that can be used to download projects from Connected Components Workbench to a Micro820 PLC via USB.
The Micro830 PLC is available in 3 different form factors.
The smallest form factor has 10 or 16 built-in I/O points and can be extended with up to two plug-in modules.
The medium form factor has 24 built-in I/O points and can be extended with up to three plug-in modules.
Finally, the largest form factor has 48 built-in I/O points and can be extended with up to 5 plug-in modules.
Regardless of the form factor, all Micro830 models support up to 3 axes of motion control and include an embedded USB port for program download and a non-isolated serial port for communication with external devices like an HMI, barcode reader, or modem.
The Micro850 is one of the largest controllers in the Micro800 family in terms of features, I/O capacity, and memory capacity.
Micro850 PLCs are suitable for controlling larger standalone machines that require flexible communication options.
A Micro850 PLC includes all of the features of a Micro830 PLC as well as support for the EtherNet/IP communication protocol. This is a key feature of Micro850 PLCs since it allows you to more easily connect a Micro850 to other Rockwell Automation products like variable frequency drives, servo drives, and HMIs.
Micro850 PLCs also support up to 4 expansion I/O modules. Expansion I/O modules are clipped to the side of the controller to extend the I/O capacity of a controller beyond what's possible using plug-in modules. Using all of the plug-in module and expansion I/O slots, a Micro850 PLC can support up to 132 I/O points.
The Micro870 is the largest, most powerful PLC in the Micro800 family.
It has double the memory capacity of a Micro850 PLC which means that it supports up to 20'0000 program steps and supports the use of upt o eight expansion I/O modules. Watch out - when using more than four expansion I/O modules, an expansion power supply module must be used to power the additional modules.
I've mentioned plug-in modules several times in this post so I want to take a minute to clarify what a plug-in module is in the context of Micro800 PLCs.
Plug-in modules allow you to extend the functionality of a Micro800 PLC without increasing its footprint by plugging an expansion module into the front face of the PLC.
The most common types of plug-in modules are:
As you can see, plug-in modules can be used to add I/O capacity, communication capabilities, and specialty functionality to any Micro800 controllers (excluding Micro810 PLCs).
In contrast, Expansion I/O modules can only be used to I/O capacity to Micro850 and Micro870 controllers.
Now that you know the features and functions of the different Micro800 PLCs, you may be wondering which PLC you should buy to learn PLC programming with.
The answer is subjective and depends on your plans and your budget.
If you don't have the money to spare, then you shouldn't buy a Micro800 PLC. If you are just starting out, Connected Components Workbench has a built-in PLC simulator that has enough functionality to get you started. Eventually, I recommend that you buy a Micro800 PLC to get some hands on experience with hardware but there is no rush to do it.
Once you have some experience with PLC programming and decide to invest in physical hardware, you have to decide what you are willing to spend today to have flexibility in the future.
If you don't have much of a budget, then I recommend buying a Micro820 PLC. This PLC will let you get hands-on experience with PLC hardware without spending too much money. The drawback of a Micro820 PLC is that it does not support motion control.
If you think you would like to build a home automation lab or learn about motion control in the future, then I advise you to buy a Micro850 PLC. This is a powerful PLC that makes a great base for an automation lab and can be used to learn PLC programming as well as other topics like drive and motion control.
To encourage people to invest in Micro800 hardware, Rockwell provides some PLC Starter Kits. These kits include everything you need to get started with a specific model of Micro800 PLC including PLC, power supply, programming cables, and, in some cases, an HMI.
I'll introduce the Micro800 Starter Kits and show you the contents of my Micro800 Starter Kit in next weeks post. If you haven't already, make sure that you subscribe to the mailing list below to be notified when that post is released.
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