How do I acquire data at different channel speeds with DAQ Assistant

[RayW]

I am using Labview 7.1 with SCXI-1600 and SCXI-1102.

How do I configure DAQ Assistant so that I can acquire different channels at differing speeds ?

[Kurt_NISalesEngineer]

Hi,

I'm wondering what kind of DAQ card you might have. 

I understand that if for example if you put two DAQ Assistants on the block diagram and they are addressing the same card you may find

that you will get an error message saying resources are reserved. i.e.

This error is the result of a resource conflict when two DAQmx tasks are attempting to perform the same type of operation. With multiplexed data acquisition boards (E-Series and M-Series), only one analog input and one analog output task can be run at the same time. This is the case because all analog input channels require use of the same channel multiplexer and sample clock.

Check these excellent knowledge base links that will hopefully explain things further for you:

Causes of NI-DAQmx Error 50103 "The Specified Resource is Reserved"

http://digital.ni.com/public.nsf/websearch/04BEDD9E9E91ED3486256D180048116D?OpenDocument

Why Can I Not Put More Than One Type of Measurement Into My DAQmx Task Using the DAQ Assistant?

http://digital.ni.com/public.nsf/websearch/89B7218072F1CAF686256DC500722B6E?OpenDocument

How Can I Take Buffered and Single Point AI Simultaneous Without Getting Error -50103?http://digital.ni.com/public.nsf/websearch/457CF2AA0F9B7B2086256E3D00720441?OpenDocument

Since the DAQ Assistant is composed of lower level DAQ MX vi's i would advise you to look into using these vi's to allow for greater manipulation and also advantages like make your code redundent of excess code that the daq assisant has, that you may not use or ever need in your application. If you want to see how the DAQ assistant works i.e. the code behind it ... right click > from the shortcut menu select > open front panel to convert it into a subvi.

I hope this helps!

Kind Regards

Kurt

[Kurt_NISalesEngineer]

with the first link i have posted check out:

Case 1: Using multiple DAQ Assistant Express VIs for different instances of analog input.

All the best

Kurt

[IanW]

If your requirements aren't too demanding you can scan all channels at the fastest rate and reduce the data for the slower channels. I've done this with pressure signals at 1000 samples per second and temperatures at 10 samples per second.

Ian