Sequencing the order of operations

[m-s]

Hello,

I am a newbie to Labview but hopefully am learning fast.

Since a VI or any element of a VI executes only when all its inputs are present, the error in and error out pins on VIs are often used to sequence operations properly. However, some of the vendor supplied VI's that I am working with lack these pins, or when they do have them, they have a different dimensionality than 3 (the usual error cluster size in my application). To force correct operation, I was thinking of defining a VI with dummy inputs and outputs, which when interposed between one or more of such poorly designed VIs, would act as a delay box of sorts, forcing the correct order.

Is this the usual solution employed or am I missing some Labview feature that already does something like this ?

Thanks.

[Will.D]

Perhaps the best solution would be to edit your vendor vi's (always make a backup of the original!), such that they have the correct error in/out terminals.  Then there would be no need for any wrapper vi.  I imagine, depending on what other inputs/outputs there are to the vendor vi's, that configuring the terminals of your wrapper could become quite annoying.

The other thing I do, if I'm feeling particularly lazy, is just to create a sequence structure, drop the offending vi in there, and then wire the error through the sequence structure.  Not pretty, but it's easy.

Message Edited by Day on 09-25-2006 01:41 PM

[tbob]

Day's method of using the sequence structure is what I use.  What surprises me is that there are some NI functions that don't have error in and error out, and they should have, like Read Characters from File.  I wish the delay function had error in and out.  I could use the Express VI for delay, which I don't like because it is not backward compatible to older LV versions, so I am forced to put the ordinary delay in a sequence structure.