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VI only works the first time its called

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My LabView program stopped working yesterday and I'm finding it impossible to fix it. Hoping someone here can help.

 

The problem is manifesting as a failed test within a test sequence, where DIO should be triggered to move a pneumatic part of a machine. When a digital output line is triggered, the machine moves, and I do a VISA read from the device under test. The machine is not responding to the digital signal, and nothing moves, so my VISA read comes back empty. However, both the DIO and VISA have already been used in a prior test without issues. 

 

In a previous test, the same DIO VI is used, with a different input as it triggers another line which is needed for that test. This works perfectly fine, and even if I change the input to this VI to the input that isn't working in the sequence, it still behaves as it should and moves the correct part of the machine. Both tests are contained in different VIs, but use the same DIO control VI. My best guess is that since the DIO works in the first VI and not in the second, they are somehow using a different version of the DIO VI, even though if I open it up it seems to be the same.

 

I believe I created some conflict/new path errors by accessing the files of the project through a network share. Even though I just opened them and didn't edit anything, there appeared to be lots of conflicts today. I've gone through them all, disconnected from the network drive and painstakingly pointed every file back to the correct path. But still the problem remains - I can get halfway through my sequence before the DIO decides to stop working. Always on the same stage of the sequence.

 

Any advice greatly appreciated, thanks.

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Hi,

 

Could you please post your VI ? With only the description it is not enough.

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@ONse wrote:

My LabView program stopped working yesterday and I'm finding it impossible to fix it. Hoping someone here can help.

 

[...] When a digital output line is triggered, the machine moves, and I do a VISA read from the device under test. The machine is not responding to the digital signal, and nothing moves, so my VISA read comes back empty. However, both the DIO and VISA have already been used in a prior test without issues. 

[...]


I would take a closer look at this step. Can you verify in hardware that the correct digital signal is sent at all? Can you set a break point before the signal is sent?

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The break point is a good starting point, also verify if the signal is going out, verify that the IO is working. Try running NI Max without the Labview to see if the DIO is properly working and your machine is responding properly. Measure the output signal with a multimeter to ensure that the hw is working . 

 

 

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Accepted by ONse

Thanks for responding, I've discovered this morning that its a hardware issue (broken solenoid) so not Labview at all :). I was getting lots of conflict errors which was a bit of a red herring leading me down the wrong path. Thanks anyway 

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