How to map/move from one controller to another via Tag Scripting in Ignition Edge 8

Leveraging Ignition Edge 8 on the groov EPIC and the available Compute Module from Inductive Automation, you can utilize tag scripting to pass tag data from one controller to another in Ignition Edge 8.

Of note, this is an Inductive Automation Ignition solution on moving data. You can find the steps to configure controllers in Ignition in our online training.

In the example below, I have some tag data coming into Ignition from a controller. The tag is called “Circulation_VFD”. I want to write that data to a tag in a second PLC called “WriteValTo”. As you can see “Circulation_VFD” has a value while “WriteValTo” is empty(0).

Double clicking on “Circulation_VFD” opens its tag properties. We are going to focus on the Scripting Section → Tag Event Scripts:

Clicking on the pen icon to the right of Tag Events Scripts opens the scripting window. For this we will use the Value Events->Value Changed Script:

Click into the scripting area and we will use the system.tag.writeAsync(tagPath, value) function. This function takes two parameters, the tag path and the value to write. In the upper right we will select the tag image, and it will open the tag browse window. We can navigate to the tag we are going to right to and select it.

This will place the tag path into the function. Then we can complete it by using the internal parameter currentValue. currentValue provides the current value of the tag we are in. The function valueChanged is run everytime the data or quality changes.

Once you accept and save all changes to the script and tag properties, the tag “Circulation_VFD” with the tag write script will start sending the data to our write tag “WriteValTo”.

Keep in mind this is an Ignition solution that does require the Compute Module.

From here you can adjust the scan rate. Best practices dictates that there is little to be gained by going faster than 250ms.

Please post and let us know if you use this in an application.
(Or if you find the instructions unclear in any step along the way).


This is really helpful, It worked for me

The instructions are detailed and easy to follow.

Thank you Opto22 team, really appreciate it.

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As far as I understand it, the EDGE Compute Module is not included in the OPTO22 GROOV-LIC-EDGE License Bundle when purchased from Opto22. You will need to contact Inductive Automation or an official resellers to purchase the Ignition Edge Compute module in order to update your exisiting license code. List price for this module is US$ 400

Assume that Ignition Expression tag can still be used on Ignition Edge 7.x to link/map tags.

Thats correct. It was only changed in Ignition 8. For Ignition 7 you can still use Expression tags as shown here:

Hi, is the number of acessible bacnet devices still limitted to 2 or that number invreases if we purchase and install the compute node? How do we increase the number of acessible bacnet nodes in edge 8? Do we need to get the full ignition 8 version to do that? Thanks

Hi @pons.tugonon1
I will confirm with you shortly but I believe that you do not get extra devices by simply adding a compute module. I do believe that you will need to use full ignition 8 for what you’re trying to do.
PS: Have you tried using CODESYS? They have a BACnet driver with no device limit. CODESYS BACnet SL | CODESYS Store International

Ignition EDGE 8.1 is limited by default to two device connections. If using groov-EPIC or groov-RIO2, one of these connections is obviously the Opto22 device) You can purchase a license upgrade from Ignition or Official Distributers to allow additional device connections at US$100 per device. (Excluding care support package) This has nothing to do with other EDGE module options you may wish to add such as EDGE compute. Doing the maths, epecially if you require MQTT, its still works out cheaper to pay for additional device connections than to switch from an EDGE to an unlimited FULL license until you hit about 18 devices. Another question is if you really should be trying to connecting and heavy data scanning 18 devices to a groov EPIC PR1 running Ignition EDGE 8.1

Its actually best not to sleep too much these days as when you wake up things have usually changed. :ok_man:

As an update to my earlier post, it’s true that the Ignition EDGE 8.1 Gateway by default is limited to two device connections, but it’s also true that it can also connect as a Client to two OPC-UA Servers connections.

So, thinking slightly out of the box, if you are using 3.4 or later firmware in groov-EPIC or RIO, you can now use the embedded Opto22 OPC-UA Server to publish Opto22 device data and then use the Ignition OPC-UA Server to make a client connection to get its published data into the EDGE Gateway.

This uses an OPC-UA client connection and not a device connection, so you can now connect 2 PLCs and your groov-EPIC to your Ignition EDGE Gateway.

If your PLC device also includes an OPC-UA server you can now have up to 4 connections for the EDGE Gateway without having to expand the license for more device connections. Just saying…

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