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Block Diagram Errors....Tunnel: missing assignment to tunnel


  I am getting an error in the block diagram that is driving me crazy, here it is..."Block Diagram Errors....Tunnel: missing assignment to tunnel" , the details of the error are as follows...

The Case or Event structure does not have anything wired to the output tunnel in one or more cases. Since only one frame of the structure is executed, every frame must assign values to all the outputs.  Right-click the tunnel and select Use Default If Unwired to relax this requirement.

When I click on the "Show errors" button , the case selector is highlighted. The clue here is that the case is a empty case for a value where nothing happens.
Any clues?


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Message 1 of 18
Please attach your VI if the following does not solve your problem:
I assume the othere cases are NOT empty and wires lead out of them. Since the empty case has nothing wired to the output tunnel, it will show as an open square and generate an error.
You have two options:
  1. right-click on the open tunnel and select "use default if unwired". Now it is shaded and the error disappears.
  2. wire a diagram constat to the output tunnel. Now it is solid and hte error disappears.

Also make sure you don't have any objects or structures hidden under the case or inside the case but clipped by the boundaries.

Message Edited by altenbach on 02-10-2006 09:25 AM

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Message 2 of 18
Have you done what it tells you to do?  Have you made it "Use Default If Unwired"?

If you have and you still have errors, perhaps you really have two different tunnels that are overlapping.  This is a problem that is difficult to find.  Basically what happens is that one of the wires that should be connected to the tunnel is not connected to the tunnel but is instead connected to its own tunnel.  Kind of hard to expain, but click on the tunnel and move it.  If this is the problem, there will be one underneath of it.

If these are not helpful, maybe you will need to give us some more information.

Hope that this helps,
Bob Young
Message 3 of 18

  Thanks for the help, I had a bunch of junk that I could not see and when I deleted it everyting was ok!

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Message 4 of 18
Thanks for your tip; I had the same problem. Turns out I had four output tunnels on top of each other. I'm not sure how I got that many, but I have more than fifty cases, so most of them were made from duplicates of others. Maybe NI could generate a warning for tunnels hidden by other tunnels.
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Message 5 of 18

I get this error.  I search and search and cannot find the unwired tunnel.  Is there an easier way?  The only way that I have used to find the problem is to delete the structure and then try again.


This has also happened to me on other occasions.  There should be a way that LabVIEW can point to the bad tunnel.

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Message 6 of 18

I finally found the bad terminal.  It was hidden by the case structure.  LabVIEW really needs a simple way that one can be guided trying to find them.  It took me 30 minutes to find the problem.

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Message 7 of 18

Click on the broken run arrow.  It will list all your sins in a dialog box.

(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.
Humble author of the CLAD Nugget.
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Message 8 of 18

There is a simple way: it's called using best practices and not putting structures on top of code. And even if it was covered, if you just hit Show Error on the Error List window, it will highlight where the error is no matter what's covering it.

Test Engineer at Moog Inc.

Saying "Thanks that fixed it" or "Thanks that answers my question" and not giving a Kudo or Marked Solution, is like telling your waiter they did a great job and not leaving a tip. Please, tip your waiters.

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Message 9 of 18

Not everyone is perfect.  Sometimes when you remove all broken wires, one finds that an important one was deleted by mistake.  Good software design makes it easy to debug.

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Message 10 of 18