Wrong data flow values

[Ed_from_Wisconsin]

A reasonably simple Labview program fetches spec limit values from a config file, reads actual valus, and then compares expected to actual.

The config file reading is Good. But the values flowing into a Sequence Pane are incorrect. The Labview data probes demonstrate this incorrect behavior.

There are two screen dumps in the enclosed file.

Screen #1 show probes 4 and 5 fetching the correct values from the config file.

Probes 1 and 2, inside the Sequence  panel, are incorrect. Since the data flows are connected, probels 5 and 1 are expected to have the same value. This is not the case, Additionally, probes 4 and 2 are expected to have the same value. This is also not the case.

Screen #1 shows the correct mapping of the config file values to the dat aflows. The only thing done to correct the error was to delete the vertical flows (line containing probes 1 and 2) and the Sequence entry points. When the same lines and entries were re-created the problem has disappeared.

Any thoughts regarding what was occurring and how often this could happen?

The only reason I was able to detec this error is the print statement I was using to log the measurement activity.

[Mark_Yedinak]

First, you should either post an actual picture of the code in the post (not in a Word doc) or preferably post the code itself. More than likely what happened was that you had moved a wire a some point or had auto-wiring turned on and mis-wired the lines to the tunnels. LabVIEW can get funny that way in that it can create two 90 degree bends in the wire that run along the border of a structure and are not visible. Visually it looks like things are wired correctly however they actually are not. It is common to see this type of error in a case structure on an output tunnel when wiring a line through the case structure and manually wiring each case. From time to time you actually create a new tunnel and it sits on top of the other. You get a broken arrow on the VI yet everything visually looks fine.

Without seeing all of your code I would wonder if you actually need the frame structure at all. Proper use of data flow can easily eliminate the need for using frame sequences the majority of the time.

[Thoric]

As Mark points out this is likely a confusion created by hidden wires under the frame of the flat sequence structure. To quickly check if this is so, drag a large selection box over the two terminals and the connected wires that carry the two values into the structure and press CTRL+U to do a selective cleanup. If there's any wiring confusion then cleanup will move the wires about to make any cross over visible.

This kind of thing can happen occasionally when auto-wire is selected and one is refactoring or cleaning up code. 

[Ed_from_Wisconsin]

Well, the Ctrl-U didn't show anything, but I like the rationale of the suggestion.

So, I selected one of the wires and manually did a "Clean Up Wire". The resultant change was unexpected as it seems one of the tunnels has no connection.

I know that is not true, in  the original drawing, as both values are seen in the data probes. If there was a missing connection, the string formating and data probes would not show both the value 0.3 and 0.8. Only one of these values would be available in the sequence if a tunnel was not connected.

[billko]

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@Ed_from_Wisconsin wrote:

Well, the Ctrl-U didn't show anything, but I like the rationale of the suggestion.

So, I selected one of the wires and manually did a "Clean Up Wire". The resultant change was unexpected as it seems one of the tunnels has no connection.

I know that is not true, in  the original drawing, as both values are seen in the data probes. If there was a missing connection, the string formating and data probes would not show both the value 0.3 and 0.8. Only one of these values would be available in the sequence if a tunnel was not connected.

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I dunno - unless there's a weird bug that I'd never heard of, "cleanup wire" never lies.  But maybe it's hiding the truth.  If you can, do a cleanup of that general area just to make sure that there aren't any hidden goodies that make it look like there is nothing connected.

[Mark_Yedinak]

Please post the code or embed the picture. You can create a VI snippet which is very easily embedded in the post. Many people will not open Word documents attached to posts.

[Thoric]

Looking athis second document there are overlapped wires (sometimes the cleanup utility doesn't do a perfect job!), but the only way we can detemrine the true issue here is if we can have the code.

I'f you're worried about sharing your code, create a copy of this subVI and remove all the extraneous code to help redact it sufficiently for publishing on here 🙂