NI9269 USB DAC : _ao0_vs_aognd channel not showing up as internal channel

[kanti.dasgupta]

Hi,

 I am using a USB DAC 9269 (4 channel analog voltage output) with Labview 2014 and DAQMx version 14.0.0.

The module shows up correctly when I run Labview and I am able to use the DAQ functions (setting channel voltages) from my programs. However I also need to do a readback of the value that is

currently set.

I understand from several posts that I should be able to use the "Internal channel"  _aoX_vs_aognd

(X=0,1,2,3) to read back the values. However if I try to configure an input to a "build task" after enabling the "internal channels" , the browse window for selecting channels is still empty.

Are these channels only available for PCI systems and not USB chasis based systems?

Or is DAQMx 14.0.0 too old for this ?

Regards-

Kanti

[GerdW]

Hi Kanti,

However I also need to do a readback of the value that is currently set.

Why?

Your VI should always know the current state of that AO channels!?

[kanti.dasgupta]

The reason I want to do a readback is as follows. 

Most of the times I would be ramping the output voltage at some rate - while it is obviously possible to keep a variable updated (while setting the channel value), at the beginning of the program (when the vi first starts) I have to *assume* that it is zero. This is correct most of the times but not always - a readback is the safest and fullproof solution.

Regards-

Kanti

[GerdW]

Hi Kanti,

at the beginning of the program (when the vi first starts) I have to *assume* that it is zero.

This is correct most of the times but not always - a readback is the safest and fullproof solution.

At start of your program you could read a file, which yu used to store the latest setting of your AO channels. This would be a fool-proof situation…

I still don't get why you need to (re)start your VI when you already output some voltages on those AO channels!?

When I switch on a testbench in the morning all output channels are zero (or on their predefined default value). And as long as the testbench is running my program always knows about the current state of the AO values…

[ericericeric25555]

Did you find a solution to this problem?