How can I acquire the data from 3 separate Channels of SCXI1300 simultaneously?

[jingrui]

I am trying to build a DAQ system, which can collect the data coming from 3 different channels. I am using the SCXI 1300 board, Labview 8.0. I used 3 separate DAQ Assistant module to build the system, but it can not collect the data from the 3 channels simultaneously, it can only collect the data from one channel by another channel. So I am wondering how could I fix this problem or rebuild my system.  Thanks

[Dennis_Knutson]

Simple. Use one DAQ Assistant with 3 channels. When you first used the DAQ Assistant, you should have paid a little attention to the help that explained how to select multiple channels. Now that you have a DAQ Assistant with a single channel, doulbe click on it and in the properties window, click the 'Add' button.

[jingrui]

thanks for your reply. But actually I've already tried this method, but a window kept popping up and reporting the error to say my sampling frequency is too large. Then I tried to decrease the sampling frequencies, but the window did not stop popping out until I set the sampling frequency to 1. I just don't know what's going wrong.

[Dennis_Knutson]

Why don't you post your code. And at the same time, provide the actual DAQ hardware you are using. The SCXI-1300 is just a terminal block.

[jingrui]

hi, the DAQ hardware is PCI-6024E , and the code is like the attached file shows. 

[Dennis_Knutson]

No, that is an image and not code. All that anyone can tell is that you still have 3 DAQ Assistants.

[jingrui]

Hi, Denis, thanks for your patience. 

The attached files are the codes. I used one DAQ assistant and chose 3 channels in one program, in this way I don't know how to display and save every single signal, so then I used 3 DAQ assistant and chose 1 channel each to display and save every single signals.  If I used 1 DAQ assistant, I can not get any signal, but if I used 3 DAQ assistant, I can get the signals, but they were not collected simultaneously, so how can I sychronize the collection?

Thanks

[Dennis_Knutson]

All you have to do to get three different displays or three different files, is to use the Split Signals function. this is on the Express>Signal Manipulation palette.

[jingrui]

Hi, Dennis

I tried to use the NI-DAQmx to replace the DAQ Assistant to do the 3-channel data acquisition simultaneously, and I did the signal splition as you told me. The program works fine for 1-channel data collection, but if I chose 3 channels to do the data acquisition simultaneously, the program could not wokr, and  a warning window  kept poping up, and the window tells me the maximum sampling frequency is 0.952. So I am wondering what is going wrong and how to fix it.

The attached files are the code and the screen shot of the warning window, please check them.

Thanks

Jingrui

[Dennis_Knutson]

I don't get any error when I choose 3 channels of a PCI-6024. What is the exact string you have entered in the physical channel control? What exactly is the SCXI-1300 connected to? Is it going to an SCXI module that you have connected to the PCI-6024?