USB 6008 limited to 8 distinct channels in physical channel list

[Steve_TDiode]

It seems that the USB-6008 DAQ device is limited to having 8 distinct channels in its physical channel list.  Trying to scan for example ai0 five times in a row followed by ai1 for five times by passing a string "dev1/ai0,dev1/ai0,dev1/ai0,dev1/ai0,dev1/ai0,dev1/ai1,dev1/ai1,dev1/ai1,dev1/ai1,dev1/ai1"results in error -200284 "Some or all of the samples requested have not yet been acquired"at DAQmx Read (after Timeout).  Note that the DAQmx Create Channel vi needs its Name to Assign input to have distinct names for any channel that is repeated in the channel scan list (for example "1,2,3,4,5,6,7,8,9,10").  This error does not occur with a simulated 6008.  Other daq devices are able to repetitively sample the same channel hundreds of time in this manner.

The reason for such repeated same channel sampling is for averaging when acquiring more than one channel and avoiding channel ghosting if the channels were acquiring in sequence (0,1,0,1,0,1, etc).

Steve

[J-Barticus]

Hi Steve,

I believe there are only 8 channels in the USB-6008 scan list. The firmware of the device is expecting at most 8 specified channels because there are only 8 analog input channels and therefore does not cooperate when you include more.

-Jake B.

[Steve_TDiode]

Jake,

 Other daq devices are able to accept many more channels in their scan list than they actually have physically available.  For example, I have been able to define hundreds or thousands of channels.  This seems to be a 6008 device specific limitation.  Another engineer stated that this will work when acquiring continuously rather than finite.

Steve