read multiple analog inputs at the same time

[Chairat]

Now tried to do as the document via 1 Daq Assistant  but still not working. (Example simple queue) Any Ideas? with this?

[Dennis_Knutson]

Chairat,

Please use your own thread. You hijacked this one about coding DAQmx with c++ and you are just confusing things. Not a very polite way to post.

[Dennis_Knutson]

Hongkun,

Look at the help for the DAQmxCreateAIVoltageChan function to see how to configure diff or rse. You can also configure this in MAX.

[Hongkun · Accepted solution]

Thank you for your reply! It is very helpful! I have checked the DAQmxCreateAIVoltageChan function and learn how to set the correct configuration. So I think I have solved completely my analog input problem. 

To sum up:

1, you need to read in multiple analog input lines at the same time in one single task (e.g. set the line address to Dev1/ai0:1)

2, configure the channel to the correct mode in the DAQmxCreateAIVoltageChan, such as DAQmx_Val_RSE or DAQmx_Val_Diff. Be careful, in the example code "Acq-IntClk" installed with the drive, this mode is set to "DAQmx_Val_Cfg_Default", which means the default mode is used. I strongly adviced not using this mode unless you are sure what is actually going on. Personally I find the result is changing every time even I measure the same constant signal.

3, set the correct size of the data array into which  you want to put the acquired data. For example, you are reading 2 lines, each line you want 100 samples, then set this array to data[200] otherwise a buffer error will show up.

Hope this can help the others!