LabVIEW not recognising COM ports

[QFang]

I think the reason the NI installer was unable to "handle it" in our cases is that the existing (IVI and/or Agilent DLL) has a later version number than the one in the NI installer, and either the installer or windows will not allow "downgrading" the version number. When you manually rename that file, it enables the installer to put essentially what is an older version of the file into the system, but now I'm just speculating.

[billko]

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@QFang wrote:

We use Agilent hardware all the time and occasionally run into this issue.  Most of the time we don't get any problems, but it seems to be at least somewhat dependent on the install order.

I think (been a while since I did any clean installs), if you install the LV RunTime AND the VISA Run-Time FIRST, then install any/all Agilent products after, you should be good.  I have Agilent Connection Expert living "happily" next to my LabVIEW install on my development machine with no issues, but we did recently have an issue on a deployment system because I forgot to install the VISA run-time prior to the Agilent software.. The NI VISA run-time did pop up a warning about another VISA during install, I skimmed it and thought it said that it would "handle it" but at least for me it did not.  I had to go to C:\Windows\SysWOW64 (system32 if you are on a 32 bit OS) and rename the visa32.dll, then do a "repair" (or re-run) the VISA Run-Time installer from NI. 

Basically if you right-click the visa32.dll file and look at digital signatures, if it does not say National Instruments, LabVIEW won't be happy.

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I think what happens is that if you install the Agilent software after, it automatically sees there is already VISA installed and installs it as secondary.  I think I read that the procedure for installing Agilent software with NI products is to do exactly what I described above.