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Error 50405 at DAQmx write to USB-6501



Have a critical problem.

My company uses the NI USB-6501 OEM in the setup of one of our products. Won't go into what product it is but we have sold 4 of them since this summer and they are all stationed in Norway but far away from me..

After running for a few months at the end of september I got the error "-50405 DAQmx Write (Digital 1D Bool 1Chan 1Samp).vi:2<append> <B>Task Name: </B>_unnamedTask<0>" at one of the terminals. I logged in from a remote location and restartet the computer and got it running again. And since it has happened 5 more times... Three times at the same location and twice at another.

I have added the reset device to my system but that just gives the error "-200220 DAQmx Reset<append> <B>Device Specified: </B>_unnamedTask<0> "

No USB-hub, No (un)plugging of other usb devices.

An USB - Serial adapter (UC232R-10) from FTDI is present on another port.

I'm trying to reproduce the error on an identical system right now but so far without luck..


Some of my code:

DAQmx - idle.png


Any tips? 

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My setup


 -Embedded Touch Computer

 -AFLMB-9652 Motherboard

 -Intel(R) 82801G (ICH7 Family) USB Universal Host Controller



 -WIN XP Embedded

 -Labview runtime 8.5

 -Measurement & Automation Explorer 4.6.2

 -NI-DAQmx Device Driver 9.1.1

 -NI-VISA 4.2

 -NI-VISA Runtime 4.2

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This error is caused my loss of contact with the device. Based on your description I assume that you have read the following KB:


There are several threads in our forum that discusses this issue. You can start out by looking at the link below, and follow the links that appears.


Hopefully this will help you identify and fix the problem.



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