Independent A/D sampling

[GS]

I need to be able to sample up to 8 analog channels independently. For instance I need to start up a conversion in one VI and then in another VI start up another conversion on another channel. I thought maybe the PCI-6143 should be able to do that, but when I tried it with a simulated device I get the following error:

   Error -50103 occurred at DAQmx Read (Analog Wfm 1Chan NSamp).vi:2
   Possible reason(s):
   The specified resource is reserved.
   The operation could not be completed as specified.

If it can be done are there any examples that show how to do it?

[MikeS81]

Hi GS,
you can only sample all eight channels together, because you can only start one task for the analog inputs. A solution for you could be, to configure all channels you need. Then you read all together, but convert only the channel you want.

Hope it helps.

Mike

[Bueller]

Hi GS,

The PCI-6143 is a Simultaneous Sampling Multifunction DAQ, that is there is a dedicated A/D converter for each analog channel. However, you can't program more than one task for the same action, in this case analog read. This is why probably you are getting the 50103 error.

What you can do is create one task that can read all the channels, then you can make any processing/conversion on each channel separately.

I recommend checking the " Cont Acq&Graph Voltage - Write to data File (TDMS).vi"  under  Help>>Find examples in LabVIEW.

To specify a range of physical channels, use a colon between two channel numbers or two physical channel names(Dev0/ai0:4)

It is worth mentioning also that due to the architecture of the hardware, you must sample all channels at the same rate. So you cannot set up multiple acquisitions acquiring at different rates. The workaround is to sample all channels at the rate that the fastest channel requires. You can always ignore/average the extra samples on the slower channels.