PXI-4461 connections and text based programming

[ajog]

Hi,

I'm looking for a text-based programming guide for the PXI-4461 24-bit AI/AO card.  Currently, I am able to program it similar to PXI-6259 but cannot find a way to configure it as (differential, pseudo-differential) so as to obtain the correct output impedance. 

Is there a hardware (user) guide for the PXI-4461?

I am using C# to code the PXI-4461.  How may I determine the location of classes and methods specific to the PXI-4461. 

Thanks.

Anand

[Stefo]

Hi Anand,

446x is DSA board. You should be able to configure input configuration of PXI-4461 in exactly the same way as you do it with M series board. This means, when you create task with CreateVoltageChannel.... (or similar) from NationalInstruments.DAQmx namespace, you should be able to set AITerminalConfiguration property (Differential or Pseudodifferential)

Hardware user guide you can find on the product webpage, in tab Resources, then Manuals:

DSA User Manual

446x Specifications

If you are interested in classes and methots for particular board, then propably the best would be to check device specification and then look for the way how to do it in software.

regards,

stefo

[ajog]

Thanks,

But 4461 is both AI and AO.  The acquisition guide doesn't cover AO.  In any event, the AITerminnalConfiguration class might also have a sibling class e.g AOTerminalConfiguration.

I'll check.  But it would be nice if there were a document listing the various classes and their applicability to ALL hardware capabilities. 

Anand.

[ajog]

Hi,

Also, please reference the

Ni Digital Waveform Generator/Analyzer Help that is installed with NI-HSDIO.

This document lists hardware features and programming instructions for the PXI-6551.  Something like this would be highly useful for the PXI-4461 and other cards.

Anand

[ajog]

Hi Steto,

My apologies.  I did go through the documents you referred me to and was able to find a lot of information that answered most of my questions.  This document does however, lack the rigor and detail of the NI DIgital Waveform Generator/Analyzer Help document (that installs with the NI-HSDIO driver).

Anand

[Frank-L]

Hello, ajog

To be able to set the AO Terminal configuration of the PXI-4461 you have to use the function.

"myTask.AOChannels.All.TerminalConfiguration = AOTerminalConfiguration.Pseudodifferential;"

This will allow you to set the terminal configuration to Pseudodifferential or differential. myTask in this instance is the task name that I have created. This is placed right below where the task is created as shown below.

"myTask.AOChannels.CreateVoltageChannel(.......)"

[ajog]

Hello Frank,

Thanks for your response.  Another question

Q:  Is there a programmatic way to disable the PXI-4461 DAC filter which has a -3bB frequency of 0.487fs per the spec. sheet?

Q:  If not, is there an option in the the PXI-4461 to generate step-like (square waves)?

Thanks

Anand

[Frank-L]

Anand,

I have searched pretty in depth and I do not see a way to disable the DAC filter. I was wondering if you meant the Low-Pass Anti-Alias filters on the device, as this is able to be disabled?

You can output square waves from the PXI-4481 using the C# files located at "C:\Users\Public\Documents\National Instruments\NI-DAQ\Examples\DotNET3.5\Analog Out\Generate Voltage\ContGenVoltageWfm_IntClk\CS" and you select to output a square wave waveform.

Frank

[ajog]

Hi Frank,

Is it possible to check this with your hardware team?  There is an anti imaging filter at the output of the DAC which has a -3 dB cut-off equal to 0.487 x fs where fs is the sampling frequency.  This will clearly bandlimit the output so that the edges of the square wave will show 'wiggles' which is typical of a square wave that is missing some higher order harmonics.

I do not believe I was able to install the dotNET examples with the driver correctly.  Would you be so kind as to send me a zipped version?

Thank you so much for your kind attention!

Anand

[ajog]

Hi Frank,

So it appears that as long as the actual square wave generated has a frequency much smaller (say a factor of 20) than the maximum possible sampling rate (204.8 KSPS) we should see a reasonable square wave.  This would require that the user create an appropriately large waveform array and output it at the maximum 204.8 KSPS.

Anand