DAQdx and NI 9221

[hlod]

I'm acquiring signal on module 9221 (voltage) with NI cDAQ...

If there is connected signal on module everything working OK, measured voltage is OK. But if I don't have connected anything on channels, then my results jumping for example:

-0,000549, -0,00002 .....

What I must add or change to show this result as zero (0), because I'm logging all data;

thanks

[P@Anand]

If you having any open connection you will get a sine wave pattern if you want to avoid this better not to read the values else have programming mechanism to override the values with zeros for the channels that are open.

[hlod]

And how can I "override this values with zeros"? I need automatic solution, when not measuring anything(there is also no cable on module), result is 0 value, otherwise when measuring show correct value.

[P@Anand]

That you need to have a control in the software ( May be a boolean status ) If you are connecting any hardware make it true so that it reads the actual values else make it false so you will read zero. Make sure that you have seperate boolean for each channels. Am searching any property node that tells whether the channel is used.

[hlod]

Well maybe I can add for each channel "switch" (to acquire or not), but I used DAQ Assistant for all channel. See picture.

[P@Anand]

My suggestion would be is : Do not use DAQ assistant in applications they are just for practice once you understand Data acquisition go for the low level vi's in LabVIEW you have example for that just check it out. Also you are not using the signals as waveforms so better configure them as DBL values.

[hlod]

Hmm what you mean with this:

"Also you are not using the signals as waveforms so better configure them as DBL values."

You can see on my picture that I convert dynamic data to double...

[P@Anand]

Yes but that is not required if you are directly configure that as DBL.?

[hlod]

Sorry, but I don't know where can I configure signal as DBL. Maybe you think that I use just one "convert to dynamic data..." ?

[P@Anand]

Just check the following quick example on Low level vi data acquisition. Note: You need to configure the task in MAX and use it here.

Good Luck