Allen-Bradley Micro850

Has anyone used an A-B Micro850 PLC or tried to connect to it with Ignition? These are a new tag-based small PLC that supposedly talk both Ethernet IP and/or Modbus TCP.

I presume that Ignition would talk to it one way or the other, but I haven’t tried one yet.

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Rockwell Automation only recently got their EtherNet/IP implementation working on those controllers, so I would use Modbus/TCP if you can.

I’ve used these controllers successfully with Modbus, just not with Ignition (a tiny Red Lion touchscreen). I don’t like the Micro 800 series at all, but that machine is out the door and I can go back to ControlLogix-family controllers.

Any more progress on this PLC?

I have a customer who has chosen this processor and would like to display some data on their Ignition screen. It is just a few parameters that they want to display and for inputting some setpoints. My first connection shows that I’m connected but not getting any data from it.

The Micro850 is not browsable, whether you use EtherNet/IP or Modbus.

Once you’re connected you’ll have to manually create SQLTags with an OPC item path that points to the device and uses the Modbus addressing syntax to describe what registers you’re trying to read.


thanks for the reply. I’ll give it a go with some manual modbus addressing tomorrow.

Manual addressing works fine. I would not recommend using this processor for many reasons (none really to do with Ignition). But if you find yourself needing to work with one it is possible. I read several places that the tags can be read with one of the micrologix/contrologix/logix drivers, but I tried them all and none of them get anything from the PLC. I ended up using the ModbusTCP driver. Then addressing directly in the tags, and not with the addressing in the driver itself. For example, I named the driver wastewaterSump and then to read a tag I used [wastewaterSump]C000018 to read discrete input/output 18. The PLC uses the six digit addressing and not five digits. Discrete i/o was pretty straightforward, you just put them into the modbus mapping table and number them 000001, 000002… and then you read them with ignition with C000001… The analog values were a bit more confusing. In the PLC I addressed the first few as 400001, 400003, 400005… and then tried to read them with ignition using many different formats trying to read [wastewaterSump]HRF000001. I tried HR, HRF, C, V…it was getting frustrating when I decided to try and read the second word of the tag and discovered that they work when addressing to the second word. So you set up in the PLC with the first of the two words and then read in Ignition from the second of the two. [wastewaterSump]HRF000002. Fortunately I did not need to read many tags, and once they were setup it seems quite responsive, but I really hate the PLC software for this processor and I will do my darndest to avoid using it again on another project.


How can I connect the Mico850 using EtherNet/IP?

You cannot. Only the Modbus connection is supported in Ignition.

I’m trying to use the Modbus TCP device to connect to the AB Micro850. In the set-up there is only a field for the Host Name\IP Address. I am putting the IP address there but it doesn’t work . There is not a field to put in a connection path. After the set-up In the status field it reads Connecting or disconnected. Can you offer me any assistance.

Here is some more information
Modbus Addressing AB Micro850 - Ignition - Inductive Automation Forum

Ignition must be able to make a normal network-routed connection to the Micro850. Modbus TCP cannot pass through Rockwell Ethernet/IP connection paths.

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