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Re: Connecting to multiple KVASER - Leaf Light HS at once....

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I am trying to connect 2 Kvaser (USB) dongles to my computer using LabVIEW simultaneously...

They are connected to the computer with a USB Hub but that shouldn't make any difference.


I have: CANKing CAN bus monitor program and the Kvaser SDK and their LabVIEW library also - all installed.


When I run CANKing, the program can detect both USB devices and also the 2 virtual channels - 4 in all.


When I call the the value returned is 3 - but should be 4.


I am assuming that the CANKing program uses the same API calls.


Any ideas, why the second device is not recognised??


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Message 1 of 5

Hi Sammy,


If you use the devices one at a time, does the return the proper value?



Jeff S.
National Instruments
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Message 2 of 5
Accepted by topic author sammy346

I have seen this behaviour before, it is nearly impossible to cleanly unload the Kvaser dll when it is misbehaving.  Re-starting LabVIEW may help.  If the Kvaser hardware configuration tool shows 4 channels, then the CanGetNumberOfChannels dll call should reflect this.  It is not a good idea to add or remove a device with the driver loaded.

All the best,


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I was playing around with it further again yesterday and just calling a dll directly without using the VI (which is basically the same thing).


Results have been inconsistent although I was able to get the dll to recognise four channels at one point.



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Message 4 of 5

Just came across your question here.  An answer to your question is on our website at:


As the FAQ at the link states, the problem arises due to when the DLL is unloaded.

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