Using usb-6008, and it losses communication with PC randomly

[Primaira]

Hi -

I have written a vi controlling a system that uses DI, DO, AI and AO functions on a usb-6008 board. I can run the system a 100 times over, but, at random, it will stop working. The green light on the usb-6008 will stop blinking, the vi will continue to run without any error message. The vi runs a fairly simple sequence, it does seems to be in the same area of the sequence when it fails, somwhere between steps 7-10. I can't determine if it is a hardware problem, or something in my code.

I've attached the vi.

Thanks!

[Brandon_B]

Hello Primaira,

Thank you for using NI forums.  Do you have any other USB devices plugged in your system when this happens?  Also, once the device starts communicating are you able to restart communication by simply restarting the VI, or do you have to physically power cycle the device?  Lastly, what version of LabVIEW and DAQmx are you using?

Regards,

[Primaira]

Hi Brandon -

Thanks for your reply.

To answer your questions:

There are a few other usb-6008 boards on the same pc, as well as keyboard and mouse. none of the other devices are being used when the vi is running.

I am using LV version 8.6, DAQMX version 8.7.2.

After reading through more of the forums - I found a few things I am in the process of trying -

I added a ferrite ring to the NI usb cable

I just downloaded version 9 of DAQMX - just about to install it.

The only way I have been able to get the system to run again has been to un-plug and re-plug the usb cable into the PC.

Thanks.  

[Brandon_B]

Hello Primaira,

I'm curious to see if the upgrade to DAQmx 9.0 helps, because that was going to be one of my first suggestions.  Let me know how that works out for you.

Regards,

[Primaira]

After running the system  150+ times on Friday, I thought the ferrite rings and/or DAQmx upgrade to version 9.0 solved my issue. This morning, first run, the system failed, with the usual error message 50405. Seems this is still an issue with NI usb systems?

Next step is to try and implement the device reset vi that comes with DAQmx 9.0 I guess? Any other thoughts? Losing confidence in my system by the minute.

[Primaira]

Hi Brandon -

Just to update you on my issue - I updated my DAQmx drivers to version 9.0. I added the reset device.vi to my code when the inevitable 50405 error occurs. I am able to get my device to reset programatically (as, opposed to unplugging the device), however, with the USB 6008 power on state of all DO's high, it just kills my system, even if for a brief moment.

From scouring other postings, it seems like the issue I am having is just the way it is with NI usb devices? Worse yet, with my particular board, where I cannot implement any software workarounds (reset device is no good without being to control the power on state of the hardware), the USB 6008 is rendering itself useless?

This is very frustrating. Please, any thoughts or help? I am looking into inverting all the DO's with line inverters - but this is a workaround for a flawed product........

Regards,

Mike

[Brandon_B]

Hello Primaira,

You are correct that the default power-on state for digital lines is high.  This is due to an internal pull-up resistor on the board.  For most devices you can simply connect a pull down resistor to the board to change to power-on state to low, but this method isn't recommended for the 6008 because it would end up limiting the current that the device could supply.  The recommended way is to use an inverter on your digital lines as you suggested.  This information can be found in the KnowledgeBase article Can I Use a Pull-down Resistor to Set the Default State of the Digital Lines on my NI DAQ Device?

You mentioned that you had some other USB devices on your systems as well.  Are these directly connected to USB ports or through a USB hub?  The error you are receiving is prevalent when using a USB hub.  One thing I would try is disconnecting all the other USB DAQ devices and connecting just the one 6008 directly to a USB port.  Let me know how this works for you.

Regards,

Message Edited by B.E.Z. on 10-06-2009 10:30 AM

[Primaira]

Hi Brandon -

I have already tried removing everything else attached to the PC, and furthermore, used a laptop with nothing else attached to it, with the same results. No USB hubs are being used either - all direct connections to the USB ports on the pc's.

[Brandon_B]

Hello Primaira,

This could just be an issue with the USB device.  It seems like the only sure way to make sure you won't run into this problem would be to implement the inverters we talked about earlier and reset the device each time.

Regards,

[BZajec]

Dear Primaira,

 I had a similar problem with my usb 6009.   Finally I used shorter USB cable for conection of usb 6009 and PC and now it works fine.  Perhaps this is the problem also in your case.

 regards,

 Bojan