DAQ of analog input signals - adding two channels

[Emanuel_Lab]

Hello,

who can help me with the topic DAQ of analog input signals. I want to measure analog voltage input channel AI14 and AI15 and save the datas? It is an analog voltage signal between +/- 10V. I have a NI 6351 PCI card and LabVIEW 2009.

When I add the DAQ assistant with channel AI14 and AI15 as a voltage signal, the software shows me an error. "Resource already used".

Who can help me and add channel 14 and 15 in the existing .vi?

[GerdW]

Hi Emanual,

Who can help me … in the existing .vi?

With this VI no one will be able to help: it's block diagram is way too large!

This is just a small part of the block daigram, with the navigation window on top:

The bright area inside the navigation overview marks a FullHD screen!

When I add the DAQ assistant with channel AI14 and AI15 as a voltage signal, the software shows me an error. "Resource already used".

Where do you add that "DAQ Assistent"?

Why do you even try to add the DAQAssistent ExpressVI? THere already is valid DAQmx code in your VI!

Why don't you just select those two AI channels in the "Analoge Eingänge" DAQmx channel control?

[Emanuel_Lab]

Hi Gerd,

at first thank you for your help. I am happy about every kind of tip or support.

1) With this VI no one will be able to help: it's block diagram is way too large!

What can I do to change the size? Should I try to get everything on one or two .jpg`s?

I thought that other users can open the .VI?

2) Why don't you just select those two AI channels in the "Analoge Eingänge" DAQmx channel control?

Thanks, yes I tried to select another channel, I am able to select channel 14 or channel 15 instead of channel 0 or 1. But I want to measure and save datas from four channels. AI 0, 1, 14 and 15.

Can you show me how/where to select four channels in parallel? In my opinion there is an array with AI only from AI0 and AI1.

Thanks in advance.

[GerdW]

Hi Emanuel,

What can I do to change the size? Should I try to get everything on one or two .jpg`s?

I thought that other users can open the .VI?

Yes, we can open the VI. And it doesn't help to attach images of code…

The point is: the block diagram is way to large to get any useful information from it. You need to clean up the code, create (more) subVIs and implement a useful program architecture.

Can you show me how/where to select four channels in parallel?

Create a DAQmx physical channel control.

Left-click on the arrow symbol.

Select "Search" (or similar, "Suchen" in German).

Then a list of channels will be presented: select the channels you need while pressing the Ctrl key…

[Emanuel_Lab]

Hi Gerd,

I have a lot of sub VI`s, you find them in the attachment.

Now I was able to select my favourite AI channels. Thanks to you. Now I also want to show in a "waveform chart" the values of "channel 14 and 15" and I also want to save the datas in the .txt file.

That`s not possible up to now.

[Emanuel_Lab]

Now I found the Hirarchy, see attachment. It seems, there is a good structure in the software programm.

I also added RMS (AI14) and Raw sound (AI15). But I don`t know how to show the results in the front panel and also saving datas in the txt file.

I think that the cluster to forward measurement datas has only two AI channels.

[GerdW]

Hi Emanuel,

in your image you seem to use the Shift key instead of the Ctrl key.

Shift selects a range of channels, Ctrl selects single channels…

Now I also want to show in a "waveform chart" the values of "channel 14 and 15" and I also want to save the datas in the .txt file.

Just do that!

[Emanuel_Lab]

I would like to do it, but I am not able to do it, because I don`t know how to "catch" the signal.

How to tell the software, please save also channel 14 and 15 into the txt file.

How to tell the wave chart, please use channel 14 and/or channel 15.

[GerdW]

Hi Emanuel,

the chart should be connected to the data coming out of DAQmxRead: it should display the samples, but not the content of the "DAQmx physical channels" control…

As you miss such basic concepts you should take care of those "Training resources" offered in the header of the LabVIEW board!