The Micro820 is a low cost Ethernet controller in the Allen-Bradley Micro800 PLC family. Some interesting features include:
- Free IDE
- Can be programmed with ladder logic, structured text, and/or function blocks
- At $250.00, it is considered a low cost (for Allen-Bradley) Ethernet controller
- Without adding plug-in modules, you get 8 DIs, 7 DOs, 4 AIs, 1 AO, and 1 PWM output
- Has one Ethernet port (not common for this price range)
- Has one serial port (RS-232 or RS-485/422)
- DeviceNet capability with a plug-in module
- Supports up to two Micro800 plug-in modules (complete list here)
- One MicroSD slot
Purpose
This section describes how to perform three tasks:
- Installing Connected Components Workbench
- Wiring the PLC (Mike’s PLC on a stick)
- Connecting to the Micro820 for the first time
To start programming the Micro820, perform each of these tasks in the order they’re presented. Click on the link below to see what materials you might need.
List of suggested materials
Installing Connected Components Workbench
If you’re just getting started, you’ll need to install both RSLinx and Connected Components Workbench (CCW). RSLinx is installed automatically with CCW. To install CCW and RSLinx, follow these steps:
- Open this link
- Under “Standard” in the “Downloads” section, click “Version 1x.xx Software.” As of 5/25/2017, the latest version of CCW is 10.01.
- This will open the “Website Member Sign In” page. If you don’t have a Rockwell account, you’ll have to create one to download the software. Crikey.
- Click “Sign up now” and follow the steps to create a Rockwell account.
- Once you’ve created an account, make sure you’re signed in and then repeat steps 1-3.
- Click “Accept” in the lower right-hand corner of the screen to accept the terms of the end-user license agreement.
- Choose “Direct Download”
- Download both files (parts 1 and 2) to the same directory
- Run the .exe file (part 1) as an administrator to extract the .rar files (part 2)
- Open the subdirectory that was created in part 9. It should contain a file named “setup.exe.”
- Run “setup.exe” as an administrator to install both RSLinx and CCW.
- Unless you need one of the language packs (Chinese, Portuguese, French, Italian, German, or Spanish), I recommend installing the components/features which are selected by default.
- Click next a few more times. Accept the EULA. Eventually you’ll make it to this screen:
- It can take a while to finish. A really long while. And you’ll have to restart your computer. Crikey.
Wiring the PLC (Mike’s PLC on a stick)
There are lots of ways to wire a PLC, and I have no idea which way is best for you. The method presented here is what I call “PLC on a stick,” which is exactly the way it sounds, except it’s a rail and not a stick (but you can still use it to point at people).
Think of PLC on a stick as being analogous to a microcontroller experimenter board. It works really well for the cubicle experimenter or electronics enthusiast, not so well for those in need of a legit control panel.
Before routing wires, it’s usually a good idea to put a little thought into the mechanical layout. I start with a piece of 35 mm DIN rail (say 12-18 inches) and then I find an arrangement that makes sense. For example:
Putting the power supply on the left makes sense to me because I like to visualize the input to the power supply on the left and the output on the right, but whatever works for you.
When I decide on a layout I start wiring stuff:
The terminal blocks provide a way to connect switches and indicators, but they aren’t necessary:
Connecting to the Micro820 for the first time
Option 1: Ethernet
Ethernet is probably the simplest of the two methods, since you need only an Ethernet cable. These instructions assume you’re connecting to the Micro820 for the first time.
Using DHCP
A new Micro820 will be configured for DHCP. This means all you have to do is ensure you’re network adapter is also configured for DHCP and then open RSLinx. RSLinx should to the rest.
- Power up the Micro820
- Use an Ethernet cable to connect the Micro820 to you Windows machine
- Open the “Network Connections” screen (Control Panel > Network and Sharing Center > Change adapter settings).
- Right-click on the Ethernet adapter you used in step 2 and select “Properties.” (If you’re not sure which adapter you’re using, just unplug the Ethernet cable and plug it back in. The adapter’s icon will change as you do so.)
- In the “Local Area Connection Properties” window, select “Internet Protocol Version 4 (TCP/IPv4)” and click “Properties.”
- Ensure “Obtain an IP address automatically” is selected.
- Click “OK” to close the “Internet Protocol Version 4 (TCP/IPv4) Properties” window.
- Click “Close” to close the “Local Area Connection Properties” window.
- To open RSLinx Classic Lite, hit the Windows key, type “rslinx,” and press the Enter key.
- In the list on the left, expand the list item named “AB_ETHIP-1, Ethernet.”
If DHCP doesn’t work
If the Micro820 is configured for DHCP and the DHCP server fails, the Micro820 will allocate an IP address in the private range from 169.254.0.1 to 169.254.255.254. This means that if you manually configure your network adapter to have a static IP address in the same range, you should be able to establish a connection that way.
To configure your machine’s IP address, subnet mask, and default gateway:
- Open the “Network Connections” screen (Control Panel > Network and Sharing Center > Change adapter settings).
- Right-click on your Ethernet adapter and select “Properties.” (If you’re not sure which one it is, just unplug the Ethernet cable and plug it back in. The adapter’s icon will change as you do so.)
- In the “Local Area Connection Properties” window, select “Internet Protocol Version 4 (TCP/IPv4)” and click “Properties.”
- In the “Internet Protocol Version 4 (TCP/IPv4) Properties” window, enter an IP address in the range 169.254.0.1 to 169.254.255.254. For example, you could enter 169.254.0.17.
- Enter 255.255.0.0 for the subnet mask.
- Enter 169.254.0.0 for the default gateway.
- The IP settings should be configured as follows:
- Click “OK” to close the window.
- Click “Close” to close the “Local Area Connection Properties” window.
- Now open RSLinx Classic Lite and verify the Micro820 is listed under “AB_ETHIP-1, Ethernet.”
Option 2: Serial (RS-232)
This methond requires a few more parts than the first, but is useful for debugging and of course for communicating with serial devices.
Items needed:
The first item is not needed if your computer has a proper serial port. If you’re not sure look behind your computer for a 9 pin D-Sub connector. It would like something like this:
Otherwise you’ll need an RS-232 to USB converter like the first item above. There are a number of cheap serial converters available. Use one at your own risk. My preference is to spend a little more on a reputable model rather than spend time worring about whether my issue of the day is caused by my cheapie USB to serial converter.
Wiring
Not much to it. You want something that looks like this:
If you use the parts I listed above, your wiring might look something like this:
The D-Sub adapter is optional. You just want to connect the Tx, Rx, and lines on the Micro820 to the 9 pin D-Sub connector on the serial to USB converter:
Connecting to the Micro820 for the first time (RSLinx)
- Connect your USB to serial converter to your PC/laptop.
- Open Windows Device Manager and expand “Ports (COM & LPT)” list. Unplug the USB to serial converter and then plug it back in. The port you want to use (COM11 in my case) is the one that drops out when you unplug the USB to serial converter.
- Power up the Micro820 and then launch RSLinx classic (press Windows key, type “RSLinx Classic,” and then press enter).
- Click Communications > Configure Drivers to open the “Configure Drivers” dialog.
- In the “Available Driver Types” pull down, select “RS-232 DF1 devices” and click “Add New…”
- When the “Add New RSLinx Classic Driver” pop up opens, enter a name that makes sense, like “RS-232,” and press OK.
- The “Configure RS-232 DF1 Devices” dialog should appear:
- Choose the com port from step 2 from the “Comm Port” pull down menu
- Now click “Auto-Configure.” The message “Auto Configuration Successful!” should be displayed.
- Click “OK” to close the “Configure RS-232 DF1 Devices” dialog.
- Click “Close” to close the “Configure Drivers” dialog.
- Now expand the list item “RS-232, DF1.” The Micro820 should be listed.
