How can I pass data generated in a SubVI inside a Case Structure out of the Case Structure?

Question

Hello,
I am using a USB 2701 to control a heater.  I have three SubVIs that are all working properly on their own.  I'd like to use an Enum to select which of the SubVIs is running at a given time.  The problem is that no data is passing out of the case structure.  How can I pass the temperatures and heater outputs acquired by the SubVIs to the main VI?  I've attached my some of my code below.  I can't attach more than 3 files, but you can see how the main VI is configured.  Like I said, the SubVIs are working individually, so you shouldn't really need to look at them.
Thank you,
CJones581
Attachments:
RampHeater6-21-07.vi ‏305 KB
69_Heater_Case.vi ‏23 KB
HeaterTCD6-21-07.vi ‏210 KB

Answer 1

CJones,
You might check a couple of things.
Your HeaterTCD... VI has a While loop with a stop button condition.  HeaterTCD pass out values only when it finishes running.  If it doesn't pop open the front panel (which usually doesn't happen when running a SubVI) you could run into a stuck loop because you don't have access to the Stop button.  This could appear in the form of no data being passed out (because the SubVI never stops running).  The primary VI opens the HeaterTCD VI, starts it, and waits for the VI to finish and pass final values .
Secondary note: Unless you want your SubVI panel (which probably isn't open when running the main VI) to update continuously, consider moving your Temperature Graph and Temperature oC indicators outside the while loop.  Pass final values to them via a tunnel, since the main VI will only read their values after the loop finishes running, anyway.
It might help to add error management to HeaterTCD like you have for RampHeater.  If you connect error lines with Error Outs to your main VI, that will help tell if there is an error somewhere that is preventing info output.
RampHeater SubVI has the same issue with the stop button.  It is also probably getting stuck in the While loop waiting for a manual push of that SubVI's Stop button.
An easy way to test this would be to set up a logic circuit so that when the While loop iteration counter reaches a certain number, it registers True and sends it to the conditional.  I know this isn't what you want to do long-term, but if that lets your SubVI return outputs it means that the SubVI was just never stopping.
Hope that helps.
David C, Applications Engineering
David C
Applications Engineering