Virtual Global Channels on 9234

[plessnick]

Hello,

What are the AC/DC coupling and IEPE default settings when creating a Global Virtual Channel (Voltage) linked to a DSA (NI-9234)?  These options are disabled for the voltage type virtual channel.  

I can't test it myself as I'm waiting for the hardware.

Regards,

Patrick

[DavidMN · Accepted solution]

Hi Patrick,

The default coupling setting is DC, while IEPE defaults to disabled.

Message Edited by DavidMN on 04-29-2009 01:36 PM

[plessnick]

Hi David,

I just received and tested my hardware and the AC/DC default coupling is not DC but AC.  Can this be changed in any way in MAX?

I've done my tests generating a 4 volts DC signal using a 9263 and the 9234 is reading almost 0 (while my voltmeter gives 4 volts).  If I generate a 4 volts sine wave on the 9263, the 9234 is reading it but the amplitude is a little bit reduce (3.5-3.6 V).  I have DAQmx 8.7.2.

Regards,

Patrick

[dsb@NI]

What frequency is your sine wave? The AC coupling filter characteristics are listed in the specifications (www.ni.com and search for 9234), and low-frequency tones will be progressively attenuated as the frequency approaches zero, DC.

I do not think there is any way to change the defaults for a particular DAQmx device. I recommend setting the configuration explicitly for parameters that affect your measurement. In the future, you can use simulated devices to determine defaults and even begin application development while you wait for your DAQmx devices.

Message Edited by dsb@NI on 05-11-2009 11:22 PM

[plessnick]

Doug,

The idea behind using MAX was to give more flexibility to my customer.  It would be nice that the default AD/DC coupling to be DC (like David wrote me) or configurable in MAX when configuring a Global Virtual Voltage (not accelerometer) channel associated to a physical DSA channel.  This way the user can plug the channel either in a DSA or DAQ device.

I would add a small piece of code to get the device associated to the virtual channel and set coupling to DC if this device is a DSA.  It would be nice if everything can be set in MAX.

Thanks,

Patrick

[DavidMN]

Hi Patrick,

My apologies for the misinformation.  I recommend filing a product suggestion for the ability you desire in MAX here.