Strange Problem - Cluster of References

Question

Hello guys
I had a strange problems using a cluster with references.
How to reproduce the problem:
- open a blank VI;
- create two graphs in the front panel;
- in the block diagram, create references for both graphs;
- connect these references to a bundle (not bundle by name);
- create an indicator for the bundle;
- run the VI once;
- right click on the bundle indicator and change it to a control;
- delete references and bundle;
- select the control in the front panel, go to EDIT, CUSTOMIZE CONTROL;
- change to strict type def;
- save this control as Control1.ctl;
- connect the control to a unbundle by name;
- right click on the unbundle by name and select one of the two graphs as an item (doesn't matter which one you select);
- create a property node and feed its reference terminal with the reference from the unbundle by name;
- use the property "Label.Text" in the property node;
- create an indicator for the the property node;
- run the VI;
- the indicator will show the correct label for that graph;
- perfect!!!
If you save the VI and run it again, everything is fine.
But............... if you close it, open again and run.... you will get an error 1055 "Object reference is invalid".
Why it was working before closing?
Find attached the VI and the Control.
Thanks
Dan07
Solved!
Go to Solution.
Attachments:
Cluster References.vi ‏11 KB
Control1.ctl ‏7 KB

Answer 1

Let see if I can answer before I have to start working.
Do a quick experiment.
Use a Type cast to cast your ref as a U32 and show that value on the FP.
Save the VI run it and record the number on the FP.
Mod the vi save it clsoe it open it and run again. The number should have changed.
That is the issue you facing, the ref number changes so you need one that is valid when you run.
How I do it;
I use an Action Engine (see this Nugget to learn what an Action Engine is) that servse as a GUI controller and lets me get at refs where even I need them. The following is a case study.
First I collect all of th refs I will need and bundle them in a type def. I sue a state machine to do the bundling if there are a lot.
THe bundled clsuter get passed to an GUI Controller Action Engine
Inside the Init I check the refs to make sure they are vlid. THis has saved a lot of wated time chasing invalid refs.
If they were valid I cache the refs.
For major mode changes that demand a lot of GUI punching I create sub-VI to do the dirty work.
When ever other codes needs a ref to the GUI I have a method that returns the refs.
THe following shows another VI using those GUI refs.
I hope that helps,
Ben
Ben Rayner
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