9219 Sampling with CompactDAQ and DAQ Assistant

[9219]

When I'm using DAQ Assistant with my NI-9219 Module for strain readings, I get a sample rate of around 2 Hz (High Resolution). How do I use the ADC Timing Mode with the DAQ assistant? I'm new to this, but, I need to be able to access the "High Speed" option on the 9219. I've read "How to Set the Sampling Rate of the NI-9219" and I still haven't found an answer.

Thank you

[MarkGrot]

The short answer is you can't right now.  If you were programming in C or Labview, you could set the ADC Timing Mode property as you mentioned.  The DAQ Assistant, however, exposes fewer properties than the various devices actually support.  This is to simplify the most common use cases.  If every property was available through the Assistant it would become cluttered and difficult to use.  If the property you want is not supported in the Assistant, your best bet is to program directly in Labview or C.

There is a shortcut though.  If you create a task in the Assistant, place that task in Labview, and right click on it, you can generate Labview code.  Then it is as simple as inserting a channel property node and selecting the right property.

You should also consider filling out a feedback form.  If a property is used enough it might get added to the Assistant in a future release.

[Mark_E]

Welcome to the discussion forums!

I just wanted to point you to a few resources that will help you do what you’re trying to do. There’s an awesome Knowledgebase that describes how to set the sampling rate of the 9219 and includes a picture of which property you need to use. As was previously mentioned, you can generate the code from the DAQ Assistant and then add in the property node to give you this more advanced functionality.

The other thing I wanted to mention was that to submit feedback, you would simply need to visit www.ni.com/contact and look under the heading “Product Feedback” to fill out a short form.

Hope this helps.

[9219]

Thanks for the feedback!

I'm very appreciative.

[kazemi]

Does anybody have a sample vi code? It's really hard to understand by beginners.

[BrowningG]

Hello Kazemi,

Thanks for contacting National Instruments. 

There are numerous resources for beginning with DAQmx.  The documents Using the DAQ Assistant and Using the DAQ Assistant to Automatically Generate LabVIEW Code are great places for getting started on using the DAQ Assistant to program data acquisition. 

The DAQ quick start guide located in Start -> Program Files -> National Instruments -> NI-DAQ contains great starting information on using the DAQ Assistant as well.

Once you have gotten comfortable with the DAQ assistant, Getting Started with NI-DAQmx and Learn 10 Functions in NI-DAQmx and Handle 80 Percent of Your Data Acquisition Applications are great for increasing measurement power of your data acquisition system. 

[Bill23]

Hi,

I am also having similar problems. I've looked at the knowledge base article but the pictures don't load up properly for me.

I have tried the shortcut suggested MarkGrot and it works if the only module i'm using is the NI9219. But in my set up I'm also using other modules too such as NI 9211 (thermocouples) and NI9205 and it gives me an error if I try to wire the channel property node with these also in the tasks. The help pop up says that this ADC convert time can be applied to one module only, how is this done?

Thanks

[Brooks_C]

Hello Bill23,

I believe you can still follow Mark's suggestion if you expand the DAQmx Channel Property Node to include both the ActiveChans property as well as the AI.ADITimingMode property.  I've attached a VI that has a property node with both properties that you can copy and paste into your VI.  You will need to select the channels in the task that refer to the NI 9219 so that only channels that this property applies to are selected.

I hope this helps, and have a great night!

Message Edited by Brooks_C on 06-11-2008 05:04 PM

[Bill23]

Hi Brooks,

Yep it works now. Thanks for that!

The problem before was I had the ActiveChans property selected second so nothing seemed to change. So if you select the ActiveChans property first then all other property changes you make applies only to that channel? Can you have the one channel node but have several active chans selected?

Bill

[Brooks_C]

Hello Bill23,

I imagine this would work just fine.  The thing to keep in mind is that property nodes will execute the property list from top to bottom.  If the top property is an ActiveChans all subsequent properties should apply to those channels; then if you write to the ActiveChans property again you should be able to update properties for these channels in the same DAQmx Channel property node as well.

If for some reason this isn't working (though I suspect it will), you should just use a separate property node for the next set of channels.

Have a great Friday!