MAX issues - loss of all communications

[KDillon]

I did reboot the PC - many times!  And I'm using a powered USB hub.  Still, I'm going to check all of the items listed.  I didn't even know I had to check the power save options on USB ports.

It's working now with the devices plugged directly into my PC.  I did end up having enough USB ports, but I had to unplug my mouse.  Even with devices plugged into the laptop, I did have issues with the USB module not being detected, and I had to reboot my PC to fix those.  I'm scared that when I *think* it's working, it's going to all of a sudden stop again.  I thought it was working for a week before I had this problem!

I suspect the NI USB module might be the culprit behind these issues, so I might try plugging the instruments into the USB hub and plugging the I/O module directly into the laptop.

[Chris-NI]

Hi KDillon,

I am glad to hear you have been able to get at least some of your devices working so far.  I have a couple steps you may want to try to get everything back up and running:

1. Try the NI USB device on another machine to verify the device is still working properly.  This will tell us if there is an issue with the device or the computer.
   
   
2. I have seen instances where force closing LabVIEW causes a MAX database corruption.  This can lead to unexpected behavior in device connectivity.  Follow the instructions on this Knowledge Base to reset your MAX database:
   

   What is the Process for Removing MAX Database Corruption? - http://digital.ni.com/public.nsf/allkb/2C7480E856987FFF862573AE005AB0D9

3. Your DAQmx driver may have become corrupt since it seems only the NI devices are not connecting after removing the hub.  Try downloading the latest version of DAQmx that is supported in your version of LabVIEW:
   

   Driver Downloads (search "DAQmx") - http://www.ni.com/drivers
   NI-DAQ and LabVIEW Version Compatibility (for Windows) - http://digital.ni.com/public.nsf/allkb/B0D5630C0A50D5C6862578E800459248

4. Check to make sure that NI Device Loader and (in some older versions of DAQmx) NI mDNS Responder are running in your services (Windows XP: Start»Run» type services.msc; Windows 7: Start» type services, return).

Generally speaking, force closing any application that is interfacing with hardware is not advised.  It sounds like the hanging of your code and subsequent force close of your application caused the issue to manifest.  I would recommend debugging your application either using breakpoints or Highlight Execution, depending on the size of your code, to determine where the hang is occurring.  This will help determine what is causing the initial crash as some changes likely need be made to the program.

We also have several getting started guides online about DAQ and LabVIEW that many users find helpful (some concepts may already be familiar):

• LabVIEW Basics - http://www.ni.com/gettingstarted/labviewbasics/
• Introduction to Taking an NI-DAQmx Measurement in LabVIEW - http://zone.ni.com/reference/en-XX/help/370689M-01/daqmxtutorial/introtutorial/
• Getting Started with DAQmx - http://www.ni.com/white-paper/5434/en
• Online Self-Paced Training (exclusive to active SSP members) - http://www.ni.com/self-paced-training

Regards,

[JÞB]

Nice Post Chris!

[KDillon]

Chris,

Thanks for the detailed post.  That's really helpful to a beginner like me.

1.  The NI USB device does work, but I have to reboot quite often because it will randomly STOP working.  It seems to lose communications regularly.  A reboot almost always does the trick.

2.  I didn't have to force close Labview until it locked up on me the first time because of the communication issues.

As for determining where the hangup is occurring, I know where it happened.  It was during the step of the test that initializes communication with the external instruments.  (It uses the Labview drivers made by the instrument publishers).  I'd never had issues until that one day where I came back from lunch and right after lunch, it hung up on me.  (I think I actually ran the test once, and when I ran it again it froze up).

I could post my code to see if I'm making any mistakes, but I'm not sure it would do any good since it has a ton of dependencies and you can't really run it unless you have the instruments I'm using.

I am going to take a hard look at all of these things both Chris and Jeff have posted.  Hopefully I'll come to some resolution.  I really appreciate the step-by-step responses... they've been very helpful.

[KDillon]

Okay, I was checking the version compatibility information, and I'm not sure what I'm looking at any more.  I've been using "National Instruments Measurement & Automation Explorer" version 5.1.0f0.  I looked at the compatibility charts, and the numbers don't match at all.  Am I even using the right software?  This is the tool I used to configure my USB I/O.  For what it's worth, I haven't used it for anything concerning the power supply or electronic loads - those I've strictly used the device drivers.

[Chris-NI]

Hi KDillon,

You will want to verify compatibility between LabVIEW and DAQmx.  You can expand the Software section in Measurement & Automation explorer to see what versions of these are installed.  Alternatively, when you are in the LabVIEW Environment, Help»About LabVIEW will give you LabVIEW version information.