# Subscribing whole array using Logix Driver

**URL:** <https://forum.inductiveautomation.com/t/subscribing-whole-array-using-logix-driver/14830>\
**Category:** Ignition\
**Created:** [July 19, 2017, 8:58am UTC](https://forum.inductiveautomation.com/t/subscribing-whole-array-using-logix-driver/14830 "2017-07-19T08:58:01Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![rudy.bekema](https://avatars.discourse-cdn.com/v4/letter/r/bc8723/32.png) [@rudy.bekema](https://forum.inductiveautomation.com/u/rudy.bekema)\
**Post date:** [July 19, 2017, 8:58am UTC](https://forum.inductiveautomation.com/t/subscribing-whole-array-using-logix-driver/14830/1 "2017-07-19T08:58:01Z")

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I am experiencing troubles trying to subscribe an array into the ignition opc ua server.  
Versions I am running:  
Ignition v7.9.2 (b2017041315)  
Logix driver: 3.9.2 (b2017041315)  
PLC: Compactlogix 1769-L36ERM Revision 30.011

In the PLC there is a program scoped variable:  
L\_Product\_Par.Act.Parameter.Nr which has datatype REAL[2500].  
Using our own OPC ua client we are able to subscribe to the individual elements like this:  
L\_Product\_Par.Act.Parameter.Nr[5]

But due to the size of the array I would really like to address the array as a whole like this:  
L\_Product\_Par.Act.Parameter.Nr  
Is this at all possible with my current setup?

Regards,

Rudy

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**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:** [July 19, 2017, 1:06pm UTC](https://forum.inductiveautomation.com/t/subscribing-whole-array-using-logix-driver/14830/2 "2017-07-19T13:06:12Z")

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Ignition’s OPC UA server and drivers do not currently use array types. Instead, it exposes them as folders containing the individual elements.

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<div class="post-metadata">

**Author:** ![rudy.bekema](https://avatars.discourse-cdn.com/v4/letter/r/bc8723/32.png) [@rudy.bekema](https://forum.inductiveautomation.com/u/rudy.bekema)\
**Post date:** [July 19, 2017, 3:59pm UTC](https://forum.inductiveautomation.com/t/subscribing-whole-array-using-logix-driver/14830/3 "2017-07-19T15:59:23Z")

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Thank you Kevin for your response,

how would you suggest to address the datapoints?  
I have tried putting all reals in one row and writing it into a massive STRING of 10000 characters but apparently only the default STRING datatype with a character length of 82 characters is supported by the Ignition OPC ua server.

thanks in advance for your response,

regards,

Rudy

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<div class="post-metadata">

**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:** [July 19, 2017, 4:11pm UTC](https://forum.inductiveautomation.com/t/subscribing-whole-array-using-logix-driver/14830/4 "2017-07-19T16:11:02Z")

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It does support reading custom String UDTs of any length but I think writing to those UDTs is limited to ones whose length lets it fit into a single CIP request.

If your UA client subscribes to all the elements of the array our Logix driver will read the array as a whole behind the scenes - it just doesn’t expose an array value in the OPC UA server.

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<div class="post-metadata">

**Author:** ![rudy.bekema](https://avatars.discourse-cdn.com/v4/letter/r/bc8723/32.png) [@rudy.bekema](https://forum.inductiveautomation.com/u/rudy.bekema)\
**Post date:** [July 20, 2017, 8:38am UTC](https://forum.inductiveautomation.com/t/subscribing-whole-array-using-logix-driver/14830/5 "2017-07-20T08:38:03Z")

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Instead of using a subscription I am using ReadValues of a collection of NodeID’s. The collection contains all 2500 members of the array. This gets me the values of all id’s within one message.  
This is not a subscription but it still works for me.