I'm curious what people think of the Automatic error handling options in LabVIEW. Is this something you leave enabled? Do you disable it? Why?

I disable it and wire through Error in and Error out clusters manually.

I mostly hate it, but I leave it on. It's annoying when doing initial testing. However, very occasionally it finds an error cluster which I forgot to wire, sometimes in the middle of a crowded diagram, and that makes it worth it.

I second that. The main reason for this is that I like to manage error dialogs my self.

/J

Ditto that.

Ben

I use it heavily during initial design. When code is finished, I turn it off, error cases either wired or consciously ignored.

I will third that.
For example, we have a standard VI that creates a directory. The auto error handler will post an error if the directory already exists... well... OK. That's what I wanted.. a directory there. If it's already there, then good!

As I type this I realize that if I know an error routinely happens, I should avoid it. I should probably check if the directory exists first. So maybe the auto error will point out places that I should correct.. like jdunham does.

Thanks a lot.. now I feel compeled to turn on the automatic error handling...
-James

[edit]
I just check the VI that initializes paths. I do check if the directory already exists. Sometimes I'm good and don't even know it.

This post has been edited by James N: Aug 28 2008, 01:40 PM

Ditto.

I personally turn it off all the time. I try to build in my error handeling in the begining and I like to see how my code will perform with my own Error Handeling.

This brings up something I am really interstied to learn. How do other people do their error handeling? This I think would make a great NI week topic. I have been thinking about developing a presentation on the topic but I feel I don't have scope on different methods of error handeling and comparing them to my own hair brained methods.

Dan

That's fine as long as you are absolutely sure that you get complete error cluster coverage. For example, do you wire up the errors on the "Format into String" primative? I sometimes miss those and am delighted when LabVIEW pops up an error if I've buggered something up.


We have a bunch of reuse VIs that do anything from present errors to the user, file-defined filtering, writing errors to a FIFO file, ... What do you mean by "do"?

Thanks for all the replies. I tend to follow this paradigm myself, but this brings up the follow-up question...Is it OK (from a best practices viewpoint) to consciously ignore errors? I do it when I need to execute a section of code regardless of what is on the error wire, but I want the error to propagate through. I always feel a little a little guilty about leaving those error I/Os unwired though



I would definitely be interested in a presentation on error handling. It seems there are many ways to get it done, but not really any prominent best practices on the subject.

Automatic error handling has been one of the options I turn off once LabVIEW is installed. The why is it would report errors and wait for a user prompt when the systems I work with do not have a user standing in front of them (it's mostly production equipment).


We have a centralized alarms screen that logs to a database.

I'm with the leave-it-on-but-handle-errors-camp. This is good for catching places where you missed wiring an error cluster, although if you want, the VI analyzer also has a test for this.

In any case, when you compile an executable, errors won't pop up under any conditions, so leaving it on only applies in the IDE (where it can also be globally disabled).

That said, there are cases where leaving it enabled can give you trouble. I was once asked to debug a VI which had a primitive (open app ref, I think), which returned both a reference (although an unusable one) and an error. The error out wasn't wired and I didn't think to check it because the VI was returning a reference and I had AEH on. What I didn't realize was that the person who wrote the VI didn't have AEH enabled and so the VI didn't have it enabled. Without relying on it, I might have wired the error out terminal sooner and found the source of the problem.

If you want, you can read this discussion for more.

P.S. Regarding your question, yes, there are cases where it's OK not to handle errors (e.g. certain property nodes, disconnected segments), but you have to be very careful about this.