continuous acquisition of several channels quasi-synchronized

[HarryG]

Hello,

I am using DAQ Assistant and have a PCI-6259 board.

So far I have managed to sample one analog channel continuously. The trigger and timing (see DAQ Assistant) is provided by the outgoing line of one of the two counters running at a frequency of 10 kHz.

This works very well.

However, now I need to extend the VI by incorporating the sampling of many more analog channels. In fact, each time the first channel finished the sampling, I want to sample all the other channels required, too, so that the channels are quasi-synchronously sampled.

As this appears to be a standard problem, maybe someone can provide me with a VI or some tips.

Cheers,

HarryG

[StefanK]

Harry,

simply select the channels you want to sample in DAQ Assistant and it will return this data for each channel. Use the "Ctrl" or "Shift" key to select multiple channels - have a look into the attached screenshot. The rest is done by the NI-DAQmx driver.

Hope this helps ...

Good luck

Stefan

[HarryG]

Hello,

thanks for your reply.
If I use the same timing signal for the acquisition for all analog channels, e.g. an external trigger signal, I obtain a warning from the DAQAssistant saying that the requested sampling rate is too high.

My questions are :
1. Despite the obvious error in the timing request, i.e. all channels sampled simultaneously, does the board switch into a mode in which it tries to sample teh channels quasi-simultaneously, i.e. at the highest possible sampling rate ?
2. Because of the warning, is the data aquisition performed properly ?

Thanks in advance for any advice.

HarryG

[StefanK]

Harry,

10kHz is not a thing for this board!
Could you descibe, what your application is intended to do, so that we can find a solution for your special case.
Otherwise we have to go through all timing and trigger considerations with the M- Series and this would blow this thread.
Here, some good resources - general informations about the clocks:
http://digital.ni.com/public.nsf/websearch/42484E84DA98053686256D32006E0494?OpenDocument
http://digital.ni.com/public.nsf/websearch/4D1435DF82EF494186256D8A006DD6D4?OpenDocument

With the info of these two knowledge bases and the LabVIEW Measurements Manual chapter 6 (find it in the LabVIEW Bookshelf) you should be able to get ready programming your application.

Stefan