# Dynamic OPC path **URL:** \ **Category:** Ignition\ **Created:** [April 2, 2021, 8:42am UTC](https://forum.inductiveautomation.com/t/dynamic-opc-path/45203 "2021-04-02T08:42:18Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![gediminas.labutis](https://avatars.discourse-cdn.com/v4/letter/g/f6c823/32.png) [@gediminas.labutis](https://forum.inductiveautomation.com/u/gediminas.labutis)\ **Post date:** [April 2, 2021, 8:42am UTC](https://forum.inductiveautomation.com/t/dynamic-opc-path/45203/1 "2021-04-02T08:42:18Z")
Is there a way to have dynamic OPC path for a tag ? In PLC I have a tag array structure: Tag BatchDuration path= [PLC]BATCH\_REPORT[X].BATCH\_DURATION Tag BatchStartTime path= [PLC]BATCH\_REPORT[X].BATCH\_START etc. etc. where x (batch number) =1…100 I want to address individual batch from Ignition client. But it looks like there is no way to change X dynamically ? For example by some reference tag. path= [PLC]BATCH\_REPORT[{BATCH\_NO}].BATCH\_DURATION I could import ALL batch report tags into project and then change which tag I am accessing from user interface, but that would import tens of thousands tags (for all 100 saved batches), when I only need data from one batch at a time. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [April 2, 2021, 11:23am UTC](https://forum.inductiveautomation.com/t/dynamic-opc-path/45203/2 "2021-04-02T11:23:37Z")
I think the most dynamic you can get without using system.tag.configure to actually reconfigure/edit your tags is a UDT where you use a parameter to construct the OPC Item Path. Probably not as dynamic as you’re looking for. Alternate approach could be to use memory tags and do a bulk `system.opc.readValues` to populate them for each batch you are going to deal with. ---
**Author:** ![nminchin](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/nminchin/32/6911_2.png) [@nminchin](https://forum.inductiveautomation.com/u/nminchin)\ **Post date:** [April 2, 2021, 1:03pm UTC](https://forum.inductiveautomation.com/t/dynamic-opc-path/45203/3 "2021-04-02T13:03:22Z")
Another alternative is to have the plc handle the writing of batch data into temporary tags which igntion reads. Igntion writes to an index tag telling the plc which batch to read, then writes to a bool to tell it to move that batch data into the temp tags for igntion. It’s a bit slower as you then have the plc as the middle middle man, but it might solve your issue. ---
**Author:** ![ggross](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/ggross/32/12668_2.png) [@ggross](https://forum.inductiveautomation.com/u/ggross)\ **Post date:** [April 2, 2021, 3:24pm UTC](https://forum.inductiveautomation.com/t/dynamic-opc-path/45203/4 "2021-04-02T15:24:01Z")
I may be off with the use case, but I would suggest doing a parameterized path like Kevin mentioned, but I don’t think it would be as difficult as he thinks to make it change. In 8.x, parameters can be written to like normal tags. Having a reference tag configured like the following will allow you to easily bind to the parameter and change it on the fly like any other tag: ![Screen Shot 2021-04-02 at 8.10.04 AM](https://us1.discourse-cdn.com/inductiveautomation/original/3X/b/6/b604ba43ad0e1a6929ded2c1939352a5c3023230.png) I am attaching an export of my definition here. If you bind any component to the `opcItemPath` of the members in a UDT Instance, you change the value of `_conf/motor_number` you can see how everything updates. [Example.json](https://forum.inductiveautomation.com/uploads/short-url/sI2hmoRChj40Gcoi5YUUYq6yNsA.json) (1.5 KB) Depending on how many parameters are needed, you will want to add a number of protections around this to ensure that the tags referenced are the ones you want. As tag writes are asynchronous, there is no guarantee that all values will populate at the same time. Garth ---
**Author:** ![gediminas.labutis](https://avatars.discourse-cdn.com/v4/letter/g/f6c823/32.png) [@gediminas.labutis](https://forum.inductiveautomation.com/u/gediminas.labutis)\ **Post date:** [April 2, 2021, 4:18pm UTC](https://forum.inductiveautomation.com/t/dynamic-opc-path/45203/5 "2021-04-02T16:18:03Z")
I have tried with UDT parameters, and it works if I change the parameter manually. But I cant bind parameter to a tag. It works only one way - when I change parameter, the tag connected to that parameter updates. But not the other way. Searching in the forums I have found similar request and it looks like 10 years ago that was not possible. Has that changed since ? > [@Binding UDT parameters](http://forum.inductiveautomation.com/t/binding-udt-parameters/4341/4): > > Hi Colby, You’re right, this data will not change. I just felt a bit uncomfortable with the redundancy, but it’s not a big deal anyway. I have not come yet with the need to pass variable data to the UDT, but I guess it might be very useful to have it. Thank you! ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/c/4/c4888fe20db4ddff3933a952efe1bb02b7464bb9.png) ---
**Author:** ![ggross](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/ggross/32/12668_2.png) [@ggross](https://forum.inductiveautomation.com/u/ggross)\ **Post date:** [April 2, 2021, 4:23pm UTC](https://forum.inductiveautomation.com/t/dynamic-opc-path/45203/6 "2021-04-02T16:23:20Z")
Binding to parameters wasn’t possible in 7.x versions of Ignition, but it is possible in 8.x albeit not directly. You have to create a Reference type memory tag in 8.x to reference the parameter which will allow you to directly modify the parameter (see above screenshot and example). Garth ---
**Author:** ![gediminas.labutis](https://avatars.discourse-cdn.com/v4/letter/g/f6c823/32.png) [@gediminas.labutis](https://forum.inductiveautomation.com/u/gediminas.labutis)\ **Post date:** [April 2, 2021, 4:28pm UTC](https://forum.inductiveautomation.com/t/dynamic-opc-path/45203/7 "2021-04-02T16:28:08Z")
Got it working. Thanks. Just had to write [.]/Parameters.BatchReportNo instead of [.]…/Parameters.BatchReportNo ---
**Author:** ![nminchin](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/nminchin/32/6911_2.png) [@nminchin](https://forum.inductiveautomation.com/u/nminchin)\ **Post date:** [April 3, 2021, 2:34am UTC](https://forum.inductiveautomation.com/t/dynamic-opc-path/45203/8 "2021-04-03T02:34:52Z")
> [@ggross](#): > > Having a reference tag configured like the following will allow you to easily bind to the parameter and change it on the fly like any other tag Wow, I knew all of that but it never clicked that I could actually use it in that way to make dynamic changes to my tag opcitempaths. That's awesome 😃 Damn, that would be far better I think for my recipe editor tags....... Next time! ---
**Author:** ![kaushik.shah](https://avatars.discourse-cdn.com/v4/letter/k/34f0e0/32.png) [@kaushik.shah](https://forum.inductiveautomation.com/u/kaushik.shah)\ **Post date:** [October 6, 2023, 2:24pm UTC](https://forum.inductiveautomation.com/t/dynamic-opc-path/45203/9 "2023-10-06T14:24:06Z")
Would it be possible to make changes to underlying tag JSON? I have a UDT where I would like to be able to either read values directly from OPC or Reference tags. In both cases, I have parameters. Is there a way to write a initiate function to assign the binding properties in the JSON of those tags but when I try to assign the binding it actually grabs the value for those parameters and sets that as a binding. here is my value changed event script for setup tags in the UDT : ```auto import system # Globals valueSourceBindingMap = {"opc": {"opcItemPath": { "bindType": "parameter", "binding": '{opc_device}_Meta:{opc_path}/{TagName}'} }, "reference":{"sourceTagPath": { "bindType": "parameter", "binding": '{Provider}{ReferenceFolder}/{TagName}'} } } ValueSources = ['opc', 'reference'] def initializeTagProperties(tagObject): # tagProperty = (tagObject) # logger.info('tag properties are - '+str(tagProperty)) # logger.info(str(type(tagObject))) if (str(tagObject['name'])) not in [tag.name, 'SetupTags']: for ValueSource in ValueSources: try: logger.info('Keys we are trying to delete is - ' + str(valueSourceBindingMap[ValueSource].keys()[0])) tagObject.pop(str(valueSourceBindingMap[ValueSource].keys()[0]) ) except: pass logger.info('Keys we have in dicts are - ' + str(tagObject.keys())) # if valueSourceBindingMap[ValueSource].keys()[0] not in tagObject.keys(): tagObject[valueSourceBindingMap[ValueSource].keys()[0]] = valueSourceBindingMap[ValueSource].values()[0] logger.info(str(tagObject)) system.tag.configure(str(tagObject['fullPath']).split(tagObject['name']), system.util.jsonEncode(tagObject), 'o') return if currentValue.value == True: logger = system.util.getLogger('UDTTestLogger') root = str(tagPath).split(tag.name)[0] logger.info('Setting Up Tags - ' + root) # Value source defines what JSON properties needs to be added to the Tag tags = system.tag.browse(root, {"recursive":True}).results for tagtoInitialize in tags: logger.info(str(tagtoInitialize)) logger.info('lets look at the type of the tag here ' + str(type(tagtoInitialize))) initializeTagProperties(tagtoInitialize) ``` Here are the logs: ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/7/e/7e8698cb92228bf241789c2632fe1d3d6d0fc710.png)