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Are 6501 units not interchangeable?

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I have a program that uses nicalu dll to moitor the states of inputs on a NI-DAQ 6501.  It seems that if I install the NI-DAQ drivers with one particular switch attached, the dll never recognizes a different 6501 unit.  I have uninstalled/reinstalled the NI-DAQ drivers and the only 6501 unit that works is the one that is originally plugged in.


I have wiped another PC and loaded the drivers with a different 6501 unit and that 6501 unit works, but again, no other 6501 unit works with that computer.


Are the individual 6501 units tied to hardware configuration somehow?


The main goal of this exercise is to image a hard drive with the NI-DAQ drivers loaded to install on each PC using a 6501.  Right now the image-restored PCs only work with the 6501 that was used on the original PC and they each have their own NI-DAQ 6501 units which do not work unless the drive is wiped and the OS is reloaded and then the NI-DAQ drivers installe.


Even if the 6501's are tied to a PC, I don't understand why uninstalling and reinstalling the NI-DAQ software/drivers does not work whereas wiping the hard drive and then installing the NI-DAQ software/drivers does?

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Accepted by topic author Dustin_IDI

Hi Dustin_IDI,


Devices in NI-DAQmx have names that are assigned the first time they are plugged into the PC, such as "Dev1" and "PXI1Slot5". For USB devices, these names are associated with the device's serial number, so NI-DAQmx will see the second USB-6501 as "Dev2", the third as "Dev3", etc.


When you uninstall/reinstall NI-DAQmx, the database that maps between device names and serial numbers is preserved, which is why you get different results when you uninstall/reinstall NI-DAQmx compared to when you wipe the hard drive and reinstall everything.


If you open up Measurement & Automation Explorer, you can use it to delete the old devices and rename the new device to have the name that your application expects. Another approach is to change your application to query for the names of the installed devices, as described in How Can I Programmatically Obtain the Name of all DAQmx Devices on My Machine?



Brad Keryan
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Thanks for the solution!  I also found that deleting the "National Instruments" registry key takes care of it.  I cannot recall off the top of my head which registry node it was in, but there was only one lingering problematic reference area after the uninstall.

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