Signal export not cleared after task cleared.

[pgaastra]

Hi,

I am a DAQmx newbie. Hardware: LabVIEW 8.6.1 with a USB-6251

I have just put  a DAQmx Export Signal.vi into the Gen Dig Pulse example.  It correctly rerouted cntr0 to the PFI I selected but also left the default connected.

I removed the Export Signal vi and ran the Gen Dig Pulse.vi again and found that the PFI I had routed it to still responded.  Can anyone tell me what is supposed to happen?

[aNIta B]

Hi Pgaastra,

          I think that this Knowledge Base article may help answer your questions (please let me know if it doesn't).  As well, can you explain in a little more detail how you see it responding once you've deleted that VI?  Have a good one!

[stilly32 · Accepted solution]

In addition to aNItaB's KB (which is a great resource anytime you're looking at Export signal) note that counter output uses a "lazy uncommit" on output terminals. Basically once you route a signal somewhere it will stay routed to that line until you repurpose that PFI line for something else. You can clear up the routing by reseting the device, or just tristating the line using the DAQmx Tristate Output Terminal.vi. 

Cheers, 

Andrew S

[pgaastra]

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aNIta B wrote:

Hi Pgaastra,

          I think that this Knowledge Base article may help answer your questions (please let me know if it doesn't).  As well, can you explain in a little more detail how you see it responding once you've deleted that VI?  Have a good one!

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Thanks for that, I did read that article before posting my question.  From that and other reading I had assumed that "clearing" a task would clear the hardware connection. 

I see from the next post in this thread, that if I want to "disconnect" this routing I need to tristate it or make a new connection.