How do I set the SCXI-1143 LPF cutoff frequency?

[knicewar]

I must be dense, but I don't understand how to set the cutoff frequency.  One KB article I found talked about using an AI Parameter.vi which I can't find anywhere.  Is this for an older version of LabVIew??  Another forum thread talked about setting the cutoff freq for a 1125 card and said something completely different -- to use a channel property node.  But as I understand it, the cutoff freq on the 1143 is a card-wide property, not a per-channel setting.  So I tried a device property node but it won't let be change it to write.  How do I set the cutoff freq for ALL the channels at once?  Or do I need to set it on each channel?  That seems misleading because it implies you can have a different freq per channel which is NOT the case with the 1143.

[aNIta B]

The AI Parameters.vi is in the traditional DAQ palette.  If you don't have the Traditional NI-DAQ driver, you won't have this vi. You'll find this VI under the Functions Palette»Measurement I/O»Traditional DAQ»Analog Input»Advanced Analog Input.  You should be able to set the cutoff frequency for all of the channels at once, I believe the easiest way to do this is to create a task in Measurement and Automation Explorer (MAX), and set the Cutoff frequency there.

When you open up MAX, expand Data Neighborhood.  Right-click on NI-DAQmx Task and select "Create New DAQmx Task".  Configure your AI voltage task: under the "Channel Settings" you can click on the blue cross to add all of your channels.  Under the Voltage Input Setup, click on the Device tab and check the "Lowpass Filter Enable" box, and enter your Cutoff Frequency.  You might notice that it will allow you to set different frequencies on different channels in your task, however, take note that it states "Auto Zero Mode and Cutoff Frequency apply to all channels on this device."  You'll then be able to put this task in LabVIEW (Functions Palette»DAQmx»TaskConstant).  Good luck!

aNIta B

Applications Engineer

National Instruments 

[knicewar]

The MAX solution won't work for me -- this has to be configurable from a file the VI loads in.  I guess I don't have the traditional driver because I don't see the VI.  I suppose I'll just use the channel property node.

Thanks.

[aNIta B]

One other simple way of doing this is to use the DAQ Assistant (Functions Palette»Measurement I/O»DAQmx»DAQ Assist).  The DAQ Assistant will allow you to configure your device all in one place and is pretty easy to work with, and then you can avoid using that property node.