Subpanel & queues 
Author Message
 Subpanel & queues

I'm trying to develop an application that involves a number of
subpanels that contain subvis which communicate with the main vi
through queues.

I think that what I want to do is have the main vi create a named
queue (obtain queue, create if not found = TRUE) and have the subvi
call obtain queue with the same name and create if not found = FALSE.

The problem arises when I wire things up this way and then run the
main vi.  The subpanel loads the subvi's front panel (invoke
node->insert vi), but even when I wire up a "Run VI" or "Open FP" node
with the reference branched fron the "Insert VI" node's input, I get
hung execution because the "Obtain Queue" in the subvi can not find
the queue created by the main vi.

I have reviewed the Queued Message Logging example and wonder how the
three vis in that example are linked to open one another when run or
edited.  I wonder if I need to link my vis in a similar fashion to
make the queue from the mian visible to the sub.

I welcome ideas...

For the record, I'm using labview 7 Express.
--
Todd Trimble



Mon, 19 Dec 2005 02:38:27 GMT  
 Subpanel & queues
Use data flow to ensure that the que is created prior to running the
VI...

Are you sure it's the obtain que that hangs? It would normally just
return immediately with error code 1100.
Perhaps it's the subVI that has a loop in it so that the caller's loop
hangs when the VI is run due to it waiting for the subVI to return(?)

If the subVIs are to run in parallell call them using an invoke node
with the run metod and the wait until finished set to false. Do it
after you have created the que, or make the subVIs wait until error
1100 goes away..or let them create the named que if it does not
already exist... You already have the front panel loaded into the
subpanel haven't you(?)..no need to open the panel.

Separate the subPanel concept with how you call and serve data to the
subVIs...those things are done just as before, the subpanel just gives
you a view of the subVIs panel.



Mon, 19 Dec 2005 03:22:22 GMT  
 Subpanel & queues
Thanks.

Turns out my problem was even more silly than I thought.  A reboot
fixed the problem.

My largely uneducated opinion is that I had run the thing so many
times debugging (mostly creating, but never destroying the queue) that
I was experiencing memory allocation problems.

Todd



Mon, 19 Dec 2005 23:19:24 GMT  
 
 [ 3 post ] 

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