multiple input channels

[hellolv]

Hi,

I am using cRIO-9215 trying to do multiple analog inputs and logging waveform graph and write to text file at the same time.    Sampling frequency is 500Hz.  Bumped into a few issues here.....

1.  How to create multiple channels analog inputs DAQmx?

2.  What is the difference between 2D DBL and wfm? 

3.  It would seem like my timing is all messed up.

Thanks for your time.

[Jonnie_5]

You should check out the examples that shipped w/ LV to see proper dataflow.  Specifically, search for Continuous and checkout the various acquisitoin vi's (Cont Acq&Graph Voltage-Ext Clk.vi is probably a great starting point).
In your vi, you're constantly creating the task and starting it - everytime you run the loop.  A better way is to configure the acquisition out of the loop get your data in the loop and close the task out of the loop (as in the examples).  You also seem to have skipped using the DAQmx Timing.vi, which could be a source of your problems.

1. In the LV help files, search for Physical Channel Syntax.  Ranges use colons :, or you can separate specific names w/ commas.
2. DBL outputs just the raw data as an array (to accomodate the channels).  Waveform has other info included, such as timing, channel name, etc.  In the LV help file, search for Data Formats in DAQmx.
3. see above

[devchander]

Hi Hellov and Jonnie,

thw hardware used here is cRIO. it does not work with DAQmx functions and example Jonnie has pointed

it has its own programming technique.

Look at relevant tutorials on support for cRIO programming. 

Look at this link http://sine.ni.com/apps/utf8/niepd_web_display.display_epd4?p_guid=E336C04001B860D9E034080020E74861

Message Edited by devchander on 04-20-2006 10:51 PM

Message Edited by devchander on 04-20-2006 10:52 PM

[JMota]

Hi,

It all depends on what platform is Hellolv using the 9215 module. If it is being used with a cRIO active backplane (e.g. cRIO-9104) or with an R Series board (e.g. PXI-7833R), then he definitely needs to use the cRIO Programming technique, and write the code that communicates with the IO using LV FPGA. If using the cRIO platform, I suggest looking to the tutorials Devchander suggests and the examples that ship with NI-RIO.

If the 9215 is used in the USB platform, which I don't know much about, he can then use DAQmx to communicate with the IO. From the VI that is attached to his initial post, it seems this is the platform he is working on. I apologize of not being of much help here, but I suggest looking to examples that ship with DAQmx for the 9215 (there should be at least one).

Hope this brings some light as to what platforms the 9215 can be used at.

JMota