Help needed with Wait on Notification from Multiple not working

[squidmixer]

Greetings,

In the app I'm building, I have an event structure in a while loop monitoring user-interface

interaction.  In parallel with the event structure's while loop are many VI's running in parallel,

waiting for notification to be sent from the event structure.  There are acquisition and output

loops that always run, and others that are triggered by the acquisition loop when it acquires

new data.  Before acquisition starts, all these loops must use the Wait on Notification from Multiple.vi

to see if the start button or the exit button is pressed.  I create notifiers and write them to a

functional global prior to the spawn of the event structure and other loops.  The other loops

read from the functional global and build arrays for the notifiers that they need to monitor.

Now to the problem:  Everybody is waiting for the start or exit button to be pressed.  If I

press the exit button, sending a boolean TRUE with the exit notifier, all the loops wake up

and proceed, but read a value of FALSE when they pull that notifier's value out from the array of

notifications.  Thus, they execute code for the case of the start button being pressed

instead of the exit button, and since no DAQmx tasks have been created, the program

terminates.  This is not the graceful termination I had intended for the exit button.

I can guess that it's either the use of the functional global of notifiers, or that each loop

builds an array of notifiers from the globals that's causing the problem.  However, I need

the loops to be outside of the event structure so that the acquisition and analog output

can run in parallel and continuously while the front panel is monitored.  I can't do what

I could do in LabWindows which is launch the data acquisition thread when the start

button is pressed.  To do this within the event structure would lock the user interface

since the acq thread requires the user to press the stop button to terminate and the

event structure wouldn't be able to check the UI until the thread terminated.

Any suggestions?  I'm relatively new to LabView (we're using v7.1), so every little bit

helps.

Thanks,

Kevin

[squidmixer]

OK, so I broke it down into a far simpler loop-based task.  The event structure

monitors the user interface for button presses (lights.vi).  When a button is pressed, a

the corresponding notifier is alerted.  Another loop waits for notification from multiple

on a built array of the notifiers, and I would think, would indicate which notifier woke

it up by which value in its notifications output was true (since a true is sent with

the notifier).  It would then decide which front panel indicator to illuminate. 

However, no matter what button is pressed, it is only ever the first element

in the notifications array that carries a true.  Is this how it's supposed to work?

I realize that things involving the user interface should be done in the user interface thread,

but this is a simple way to illustrate my question about notification.

Thanks again,

Kevin

LV 7.1

[TCPlomp]

Hi Squidmixer,

What you see is expected behaviour, the help writes it a litte bit cryptic I'll try to better explain it
.
The notifiers out output, contain an array of all notifier that have generated a notification.
The notifications output, is an array matching the notifiers output array with all the notifications.


What you could do is index the 'notifiers out', do a 'get notifier' status, read the notifier name and do the appropriate action.

Ton

[squidmixer]

Hi Ton,

So if I'm understanding correctly, it is correct behavior for the first

element in the notifications array to always be the one that is signalled,

regardless of which notifier tripped it.  It then sorts the notifiers out to

indicate which one was responsible for the notification.  I'll give this a

shot. 

Thanks again,

Kevin

[squidmixer]

It worked!  Get the zero index notifier out, get its status, wire its name to a case structure,

take appropriate action.  Thanks for the help.

Kevin