lost devices while working

[nguyenduyhung]

I have three 9211 and one 6009. I must connect all devices to a single 800 Mhz , 256  M Ram , Mandriva 2006 computer with NI-DAQmx Base 2.1. The computer the two USB ports. My program uses C API to read from physical channels of a device sequentially , then switch to the next devices
- If I connect two NI devices directly to my computer USB ports, my program works fine
- But with four NI devices, I have to use powerd USB hub (My hub is D-Link DUB-H7). I got this problem: the program read physical channels of the first devices succesfully, then switch to second device. First channel of second device is then read successfully, but the second channel raises DAQmxBase Errror: -1073807346
After that, all NI devices are lost. In fact the power lights are still on but lsdaq command returns no detected devices

In the mean time, I have tested my program in other more powerful computer such as a 1.8 Ghz, 1000 M RAM, Mandriva 2006. It runs more than 1 month without any problem

Please give me some advices. Note that I can not change my hardware

[MickeyD]

Hello,

I have a couple questions.  All the information I have found about this error suggests it is caused by the DAQmx base driver when it is used in a stand alone application.  Are you making a exe file and then running it on your PC?  

If you are not building a stand alone executable, then it is going to be related to using the DAQmx base driver withthe USB hub.  I will look more into a potential issue there, but I was going to ask a few questions.  Since you are on a Mandriva system you could be using DAQmx with these devices instead.  DAQmx is a more fully featured API, so it might be in your best interestes to take a look at getting the DAQmx for Linux driver at ni.com/support.

Do the device power lights flicker off and then back on when the second channel reads and the error is generated?

I assume you have to restart your PC for the NI devices to be found again?

Please get back to me with that info and I will continue to stay on top of this issue with you.

Have a great afternoon,

Michael D
Applications Engineer
National Instruments

[nguyenduyhung]

- Are you making a exe file and then running it on your PC?

I said that I used C API that comes with DAQmx Base 2.1 (Linux ). Of course it should be standalone executable file

- DAQmx is a more fully featured API, so it might be in your best interestes to take a look at getting the DAQmx for Linux driver at ni.com/support.

As I undertand, no DAQmx for Linux has been released. Otherwise please give me the link I can download
- Do the device power lights flicker off and then back on when the second channel reads and the error is generated?

the power lights remain on all the time.

- I assume you have to restart your PC for the NI devices to be found again?

I just re-plug USB HUB cable to computer. Then lsdaq returns all devices

Thanks

[MickeyD]

Hi,

Here is the  link to use DAQmx with Linux

NI-DAQmx Version 8.0 for Linux 

Let me know if you have any difficulty with this install.

I will look into the issue you are seeing more, I think I understand it well enough to recreate it if necessary.  One question though.  It does not matter which 2 USB devices you use, before using the hub.?  Only when using the powered hub do the devices disappear?  I have not found anything else about an issue like this, but I will keep looking for USB power bus related issues.

Have a great day,

Michael D
Applications Engineering
National Instruments

[Brad_K]

By the way, the README for NI-DAQmx 8.0 for Linux says:

Not Supported on Linux
-------------------------

The following NI-DAQmx driver features supported on NI-DAQmx for Windows are not
supported on Linux:

...
* USB data acquisition products - Not supported. Refer to the "Support in NI-DAQ
  8.0" section for a complete list of supported devices.
...

I would recommend continuing to investigate why the application fails under DAQmx Base. Are you certain that the external power for the USB hub is connected properly? Trying out some different configurations may offer more insight. Some ideas:

• One device plugged into USB hub
• Two devices plugged into USB hub
• Reading channels in a different order--does it always fail on the same channel?
  
• Plugging the devices into the USB hub and connecting it to your 1.8 Ghz, 1000 M RAM, Mandriva 2006 computer (instead of using four USB ports on that PC's USB host controller)
  
• Different brand/model of USB hub
• Try different devices on the USB hub (such as a USB flash drive)
  

Brad

Message Edited by Brad K on 03-21-2007 12:32 PM

Message Edited by Brad K on 03-21-2007 12:33 PM

[MickeyD]

Hi Brad,

I apologize for my confusion.  You are correct the USB devices do not work with DAQmx in Linux.  

With regards to the original post:
Please get back to us about your issue. Brad's point  about your  more powerful PC not using the USB hub is very important.  Is that the case, or are you using the hub when you go to the more powerful machine?

Thanks again Brad,

Michael D
Applications Engineering
National Instruments