How to refer added signal from DAQ.

[KevWhat]

Hi,

I added new signal as voltage_0 on DAQ. Purpose is to subtract "ch1(voltage1) - ch2(voltage_0)". I supposed to think added new signal(voltage_0) Data port should appear on DAQ Assistant icon. But it looks not so.

How to pick new signal up to subtract ?

Best,

[GerdW · Accepted solution]

Hi Kev,

you still don't like to stay away from ExpressVIs, don't you?

Those ExpressVIs hide a lot from direct view - you always have to check the configuration dialog. Now you set that DAQAssistent to read two analog voltage - but you still get only one DDT wire…

Because that DDT wire contains all those information: use SplitSignal to get your two voltage signals! (Or use FromDDT directly after the DAQAssistent to convert that DDT wire into "more usual" array of waveforms or 2D array of samples…)

Btw. when you want the difference between two voltages you might use a differential measurement, when your DAQ hardware supports it. (Even the cheap USB600x devices support it!)

[KevWhat]

Hi

To separate two voltage signals, it looks I have to leave DAQ Assistant. Problem is I am not familiar with this Virtual Channel or whatever(Unfortunately my experience of Labview is only few weeks). Could you teach me how to call this function ?

Best,

[GerdW]

Hi Kev,

To separate two voltage signals, it looks I have to leave DAQ Assistant.

No. As written before you could use SplitSignals…

Problem is I am not familiar with this Virtual Channel or whatever(Unfortunately my experience of Labview is only few weeks). Could you teach me how to call this function ?

I already linked to that "DAQmx 10 basic functions" article…

LabVIEW also comes with a huge example library. There are a lot of DAQmx example VIs!