stop subvi without stopping toplevel vi

[bartb]

hello

I stop a subvi wth a Stop command (stop sign) but when tis executes it also stops the top level vi, is there another way. The stop command is used as a skip option.

Thnx

Bart Bakels

[PauloM]

Hi,

The stop.vi is not a normal way to stop a vi. It works the same way as if you would press teh stop button in LabVIEW.

Just terminate your sub-vi normally, it will stop and the top level will continue.

By terminate normally I mean that it don't have any more operations to do.

Paulo

Message Edited by PauloM on 07-13-2005 04:02 PM

[EdDickens]

The Stop sign is not a stop command, it's an abort button and should only be used while building and debugging your application. It stops all running VIs instantly and can leave any hardware you using in an unsafe or unknown state because it does not allow your clean up code to run. There is no way to change the way it works.

What you'll need to do is add a control to your front panel that stops the VI properly. Once the subVI stops, the main VI will resume running. Normally you'll have all your code in a While loop to keep it running and connect a Stop button from the front panel to the loops conditional terminal to stop it when needed.

Ed

[Dennis_Knutson]

You should never use the "Stop" function in a stop VI (or at all for that matter). You need to stop the subVI's while loop by passing a value to the termination terminal so that the subVI can return execution normally to the main. What are you trying to skip in the subVI. Using a state machine architecture will allow this and if you're using the sequence structure, is a much better method. There are shipping examples of state machines.

[Ray.R]

As everyone as mentionned...

Typically, sub-vi's stop because they meet a certain condition, whether it is a boolean from a control (stop button - not the stop sign), or a condition to exit a loop, or merely completing the task which causes to end (thus exit)  the sub-vi.

Experiment with some examples.  You will see that ending and exiting a sub-vi does not stop the main vi.  Unless of course that the main vi only has the sub-vi, then they will both terminate.  😉

JLV

[bartb]

the problem is that I want to have a sort of abort fuction within that subvi. the subvi consists of a lot of loops in a sequence.  and I want to abort them al at once if an error occurs. (user resses top button) The frontpanel is displayed in the top level vi with a VI panel.

[EdDickens]

This is only one of the reasons that Sequence Structures are generally not used. There is no way to stop one mid execution. It will always run to the last frame. There is no way around that without using the Abort button, which as you've seen kills everything.

You're best choice would be to rewrite the subVI and get rid of the Sequence structures. You can use dataflow between the loops to control what order they execute in, and if you carry an error cluster through the loops, you can use that to propagate your stop signal from one loop the next so they dont run.

Ed

[Dennis_Knutson]

Do NOT use a sequence structure. A sequence structure cannot be aborted prematurely except by the Stop function and that will stop your main. Replace the sequence structure with a state machine or combine an event stucture with a state machine. That will do exactly what you want.

[bartb]

in the mean time.....one year later :P... I never use sequence structures anymore. State machines are the way to do this. But i have one question.. I want a sequence of states to be run ( so state 1 then state 4 then state 8 , etc..).. and that sequence will be determind @ a state of that state machine....

for example I have a state machine VI that runs a test in every state. And the last state you can select to run the tests again that failed.. Is there a simple way to do this? maybe by using an array of states?

Greetz Bart

Message Edited by bartb on 05-30-2006 03:04 PM

[Kevin_Price]

It sounds like you're looking for a "Queued State Machine."  I think there's a shipping example and I'm sure you'll get several hits by searching on ni.com

A Queued State Machine will let you queue up a whole sequence of individual states.  Another nice feature I've found is related to error handling.  Suppose you have an Error Handler state.  Whenever you detect an error, you can use "Enqueue at Opposite End" to put the Error Handler state immediately to the front of the line.

-Kevin P.