Windows reports one set of com ports and VISA reports a different set

[old_man]

Have the wierdest thing happening.  I have several USB to serial converters on a large test system.  On one computer only, it does not give the same list of com ports.  One or more are off by 2.  I nuked the MAX database and had it rebuilt to no avail.

LV 10SP1   10.0.1 32 bit

[old_man]

Just to clarify, You can go to manage the ports and get a list from Windows.  You can then go do a Labview list of the ports and some of the numbers do not match. 

[Jacob_R]

Hello,

What version of NI-VISA do you have on this paricular machine and what version is on the other test systems? You may want to re-install the NI-VISA driver or update it.

Jacob

[old_man]

I have actually seen this now on a second computer but only once.  I am taking the original computer and completely starting over with a reformat and rebuild.  It appears to be related to using several usb to serial converters.  USB seems problematic with LabView.  I routinely get LabView hangs or shutdowns.

Just as some background, I have been a test engineer for 30+ years and using LabView since it came out.  I was on the Plug and Play Consortium committee.

[RTSLVU]

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@old_man wrote:

I have actually seen this now on a second computer but only once.  I am taking the original computer and completely starting over with a reformat and rebuild.  It appears to be related to using several usb to serial converters.  USB seems problematic with LabView.  I routinely get LabView hangs or shutdowns.

Just as some background, I have been a test engineer for 30+ years and using LabView since it came out.  I was on the Plug and Play Consortium committee.

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I think the problem is poorly built USB-RS232 adapters and/or poorly written Windows drivers for said adapters.

I have been using these adapters for years and some have total crap drivers that BSOD Windows, some wont work with some hardware and work with others, some work flawlessly for years in any computer and connect to any device I throw at it.

I have had the greatest success with the "Prolific" adapters from Cables To Go 

But even these might need the updated driver from Prolific if you are using it on a Windows 2000 or XP computer.

[old_man]

Turns out I am using the Prolific units and a stand alone usb DI\O 24 board that uses the ftdi drivers.  I have historically had lots of problems with the ftdi drivers, but it is funny Windows reports one thing and LabView another.  A short app written with VB results in the same listing as Windows.  That leads me to believe that LabView has issues with USB. 

[Jacob_R]

Hello,

I'd like to get more data points regarding this issue. May I ask what ftdi VCP and NI-VISA drivers you are using? I'd like to check whether this is a known issue and go from there.

Have you gotten your test system working?

[old_man]

I believe I got things sorted out.  Somewhere (NI?) I got a code snippet that allowed you to do a search for VISA references and change them into COMs.  As it turns out, it was simply stripping the ASRL string and taking the ASRL number and calling it a COM number.  ASRL numbers do not necessarily correspond to COM numbers.  You need to get the ASRL reference and then use the property function to get a string that contains the COM number.

[JÞB]

Also check for conflicts in the Driver specific serenum HKEY.   I once had a silly PC who's BIOS reserved COM1-4.  The serenum HKEY Start value (the lowest COM port number the VCP driver would assign) was actually a COM port reserved by the BIOS.  There went 2 days I'll never get back