What driver should I use for AB Micro850?

Hi there,

I need to establish a com with a Micro850; as it’s on-site, I cannot test it before I get over there. What should I use as a driver for this connexion: MicroLogix or ControlLogix? I suppose MicroLogix but in case…

Any input is welcome :wink:


If you read through this thread, you’ll see that ModbusTCP is the driver you’ll probably need.

Yes, Modbus TCP is the one you will have to use. So when setting up your tags they will all be done with address’s. But works very well.

Hi Phil, dcamp,

Thank you for your quick reply. You really think CIP is not an option? it’s a shame not being able to use Ethernet/IP and browse the PLC memory ;(

I don’t have one, and have no intention of buying one, but I don’t doubt Kevin’s statement in that thread that the Micro850 doesn’t support browse. The shame is on Rockwell.


I had to use the micro850 in the past, but never with Ignition. From what I could tell it’s a product Allen-Bradley bought, slapped their logo on it, and called it a day. A word of warning, if you’re using the free version of their programming software then you will not be able to make online edits. All edits will have to be made offline, compiled and then uploaded to the PLC.

Setting up the modbus addresses isn’t that hard in the Micro850, but it is annoying. I ended up making an array for each of the datatypes I needed and passing all the tags I cared about into the appropriate array. Then I can give that one array a Modbus address and it will automatically assign the correct address to each element of the array. I went with this method because I couldn’t find a way to export a tag database, assign modbus addresses rapidly in a program like Excel and then re-import the tags. Each one had to be assigned by hand in the modbus addressing area.

Good luck!

I’ve used a few other HMI offerings and been able to use Ethernet/IP CIP.

It’s still Modbus, as mentioned in this thread Phil linked to.

Hello ,

I’m using Allen Bradley Micro850 - 2080-LC50-24QWB PLC.

I downloaded a program to that PLC by CCW.

My customer wants to build an application (like a GUI) on a PC which ables to read and write the I/O’s , therefore he needs me to send him the registers of the I/O’s that i have used in the program.

so i woule like to know the register for every tag or I/O.

where can i get that information from?

for example , i would like to read : _IO_EM_DI_00 , how could i know what this tag’s modbus register is?

thanks in advance.

Hey omerd, sorry for the delayed response, I just now saw this post. With the Micro850 you have to manually assign each variable to a specific Modbus address. As I said in my initial post to quickly facilitate this limitation I created an array of the datatype that I needed (for example an array of 100 INTs) and then did move functions to take the data I wanted to be accessible by Modbus and place it into the array. Then all I had to do was assign the array a Modbus address and it would automatically populate the next 99 Modbus addresses.

The point being you would know the tag’s modbus address because you assigned the modbus address yourself. Hope that helps.

I still can’t believe that Ignition hasn’t caught up with the rest of the HMI/SCADA industry and only uses MODBUS for the Micro800 line. I’m sitting here thinking of ways to create a script in Structured Text that would auto create my MODBUS table so I can use some smart tagging, which I’ve used with Panelviews, Redlion, Exor and Wonderware.

How are other OPC servers like Kepware and Matrikon able to communicate with Micro 800 series ?
I suppose Ignition should also support 850 tags in a similar way.

They are Rockwell partners, so they get access to better documentation from Rockwell than others that are not partners.


My driver based on public resources plus a bit of reverse-engineering is coming soon. Alpha this month, I think.


pturmal, you mentioned you may have a driver soon. Any updates? If you need a tester, let me know.

Sigh. Urgent work has pushed this module back a bit. I’ll make a public alpha announcement in the 3rd Party Modules category when I’m ready for testers.

What driver should I use for AB Micro850?

Maybe the garbage truck driver? :laughing:


Ok, so this beta is way later than I originally hoped: