RingText.text property node not providing correct string

[J.CHEN]

Hi all,

I'm having a strange issue with using a text ring.

Steps of execution:

1. Programmatically set the ring string and values using this property node:

JCHEN_0-1729721533604.png

2. Read RingText.Text property but gets back <0>

JCHEN_1-1729721580048.png

3. If I use another method by indexing the Strings[] property with current value, then the returned string is correct (matching the displayed text on the ring)

JCHEN_3-1729721700429.png

Here are some screenshots from my actual application:

method using RingText.Text property:

JCHEN_4-1729721754957.png

method using indexing String[] property:

JCHEN_5-1729721797597.png

Problem is that if I take out the UI component and do it in a blank VI, the ring text property works as expected.

Expected behaviour works if code is running on a simple VI:

JCHEN_6-1729721908650.png

Anyone came across this issue?

Thanks in advance 🙂

LV Version: LV2018 32-bit

[altenbach]

Instead of a long set of pictures, attach a simplified version of your VI.

(Everything you describe seems to work fine in LabVIEW 2024, but we cannot really tell all your details)

[JÞB]

That looks like a strict type def'd control (probably set to allow undefined strings)  I would expect the "<0>"

[zou]

Add a query after step1 to see if the value gets set properly.

[paul_a_cardinale]

I'm guessing that you've got a race condition; but I can't tell because you didn't post your code.

[altenbach]

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@JÞB wrote:

That looks like a strict type def'd control (probably set to allow undefined strings)  I would expect the "<0>"

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I did not see a black corner on the terminal and since he is writing a value of zero right after defining the strings&values property, and the string&value of the first item is ["A", 0], there is no reason to expect a <0> here, even if undefined string are allowed.

And yes, we cannot efficiently troubleshoot from pictures.

[J.CHEN · Accepted solution]

Hi all, thanks for your response.

I didn't post the code because getting the ringtext.text property works as expected in a simple VI but not in my application.

Which leads me to think about the race condition in my application that @paul_a_cardinale has mentioned.

I've found the issue to be the use of defer front panel update function in a separate loop causing UI to update at an independent rate. It's all working fine now.

Thanks again.

[Yamaeda]

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@J.CHEN wrote:

Hi all, thanks for your response.

I didn't post the code because getting the ringtext.text property works as expected in a simple VI but not in my application.

Which leads me to think about the race condition in my application that @paul_a_cardinale has mentioned.

I've found the issue to be the use of defer front panel update function in a separate loop causing UI to update at an independent rate. It's all working fine now.

Thanks again.

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Technically not a race condition, but yes, if you disable front panel updates you won't have any text to read from the controls ...