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System I/O Controls

There is no I/O Controls under the system palette.  Under the Modern Controls palette there are different combo box looking controls, which (I suspect) are XControls that read information about the system and display valid choices.  Things like, DAQmx Task Name, DAQmx Global Channel, DAQmx Physical Channel, DAQmx Terminal, DAQmx Scale name, DAQmx Device Name, DAQmx Switch, RIO Device, VISA Resource Name, IVI Logical Name, and a few other depending on what toolkits are installed.


Under the System controls there are none of these.  Has anyone made the controls that behave like these, but look like system controls?  Specifically the Combo Box?  Or should I start brushing up on my XControls?


EDIT:  I should clairify that I'm actually only looking for a few of these, the DAQmx Device Name, DAQmx Scales, and DAQmx Global Channels.

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So no one is going to reply to my post that's fine I'll do it.


I was able to make an XControl that behaved mostly like I wanted with my limited knowledge of XControls.  I did however run into an issue dealing with the XControl and updating it's value when it is in a SubVI that has it's panel not shown.


I posted about it in LAVA but figured this maybe more appropriate for the type of issue I'm seeing.  Basically run the Main in the attached file saved in 2011, and you will see my issue and it can be seen here in a video demonstation of the bug/issue.


The XControl I made works just fine when it is being shown, but when it is in a VI not being shown the Data Change event is not fired, when writing to the control using the Control Value >> Set invoke node.  Why is this and is there a work around that doesn't involve polling?  This is probably a good case to use a Panel Open event if one existed.

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Hello Hooovahh,


There seems to be a dependency missing when I attempt to open your attachment, Set Enum String Could you upload you code again with this dependency included. Also I took a look at the Lava post and wanted to know if you attempted to use the "Value (signalling)" property to update the XControl, rather than the "Control value set" method?




Izzy O. 

Applications Engineer

National Instruments



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Sorry I forgot there was an OpenG dependency, the right way to get the missing VIs is to use VIPM and install the Variant Data package.  To make things easier I've attached a zip that should have all the missing VIs that I use.


In either case, yes I see that the Value Signaling event does work, but I'm not looking for a work around, I'm looking to make my XControl work in all cases that it will be used in.  I plan on distributing this XControl to other developers, and I don't know how it will be used.  I would rather have a work around that makes the XControl work in as many cases as possibly, instead of confiding how it can be used.  


This does not seem to be the expected behavor of the control and I would consider it a bug, possibly needing a CAR.

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Hello Hoovah,


Thanks for the reply. I played with your VI and you are correct the value is not being displayed on the front panel although the value is being sent to the x control. You can tell because when you wire an indicator to XControl on the block diagram of the “Sub VIwithXControl” and run the sub vi, the correct value populates, but the XControl is still blank. This issue blurs the line between a feature request and Corrective Action Request (CAR). So, I will have you submit this as a feature request and I will search and see if this CAR has been filed previously and file it if it has not.




Izzy O.

Applications Engineering

National Instrument 

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