Persisting SubVI Selections during Runtime.

[rkmadse]

I'm using an instrument from Keysight, and creating a simple VI for taking measurements. 

I am wanting to create a SubVI that allows you to select multple configurations for this instrument so that if the user doesn't like the default configurations he can go in and alter them by clicking a simple "Configure" button. 

Currently my code passes in the VISA and opens the Configure SubVI, and you can change the configuration of the instrument, but when you close the configuration window it closes the SubVI and then if the user then wishes to open the configuration window again all the defaults are loaded and the previous configuration is lost. 

Is there a way to persist decisions made by the CURRENT user of the VI during the time they are using the VI, without completely changing the default selections of this SubVI? Perhaps just hiding the VI and showing it again if needed? 

I was wanting to use a AE but there are so many inputs/outputs that it wouldn't really work for me unless I'm missing something.

Thanks,

Kellen

---

Measure VI

---

Configure SubVI

[Mythilt]

Look into Action Engines / Functional Global Variables.

Functional Global Variable here: https://decibel.ni.com/content/docs/DOC-2143

Action Engine here: https://decibel.ni.com/content/docs/DOC-34948

These use a property of uninitialized shift registers, and will allow you to hold values between VI calls.

[rkmadse]

I have used AEs quite a bit lately and am familiar with them, but what properties are used to open and close a VI if you are using it as an AE? I'd like the user to be able to pop up the "Configuration Panel" and choose the configurations, and have the window go away until needed again.

[Mythilt]

I need to ask first, is the configuration panel subVI yours, or someone elses? (ie, can you make changes to it?)

[Bob_Schor · Accepted solution]

A common technique for persisting Configuration data is to have a Configuration File that (by default) is read by your Program when it starts and loads all of the (mostly-constant) Configuration Parameters that you need.

If you want to change the Parameters, your "Configure" button calls a sub-VI that (a) reads the Configuration File, showing you the values, (b) invites you to change/edit those values, and (c) prompts you to save the Configuration file back to disk so that it can be used the next time.  You can decide for yourself if you want a single Configuration File that gets overwritten, or if you want to maintain two or three "common" Configuration Files and have the User choose which to use ("16-Channel, 1KHz", "8-Channel, 500Hz", "16-Channel 500Hz", for example).

One common "user-friendly" format for Configuration files, with support VIs in LabVIEW's File I/O Palette, are .INI files, which (if done right) are Human-readable.

Bob Schor

[rkmadse]

Yes, The configuration panel is something I threw together.

[Mythilt]

This is an example I threw together where the Configuration panel is the Action Engine as well.  The first time you call it or if you want to revert to the default values, pass it the 'Reset' command when you call it.

Bob's example is also a good one if config files are not an issue, with the advantage that the changes can persist through powerdown/closing of the main program, my example only lasts as long as the main program is in memory.

[rkmadse]

A major problem with this concept Bob is that the settings come from a lot of different controls. Bools, Ints, Dbls... etc. So how does one go about saving and retracting all of that information sucessfully from an .ini file?

[RavensFan]

The same way you would do just one of any of them.  You just have to string together mulitples reads/writes.    I'd create a For Loop and have the "i" terminal connect to a case structure inside.  Each case is the read/write relating to one of the many different controls you are trying to work with.

[TheQ]

If you are looking for a quick way to get all control values, there is a method on VIs called "Control Values-->Get All".  It returns an array of clusters of name/value pairs.  The name is the label of the control and the values are variants because of the varying data types.  I missed wiring a TRUE to the "Controls", otherwise all you get is the Indicators by default.