Pre-trigger data from four AI using Daqmx

[united kingdom]

Hello Bob,

Sorry for I did not make it clear.

In the Reference analog edge function.bmp file which I attached is the signal from my sensor, I am very sure it is very accurate.

In the another file which I used your sample.vi to acquire data from two input channels, I set the configure trigger and gate.vi property was showen in the file. In the graph, the white line is the signal which is I connect to a very low frequence sinewave from signal generator, (the purpose doing this is to provide some signal to a input channel to find out how to acquire in multichannels). The red line is supposed from my sensor, I expected it should the same as the graph in the Reference analog edge function.bmp file. because they are the same source (both from my sensor). However, they are so different, obvisouly, the red line does not show the real data from my sensor.

kind regards

Lyn

[Robert_Lee_NIUK]

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Lyn,

Thanks for getting back to me. I'm not sure why you could not observe the signal properly in the 'sample' window of the Triggering express VI. It looked like you were not allowing enough samples to be collected and may just need some more callibration. I have attached various screenshots of the Sample VI I created earlier. I have modified it so that 3 signals are analysed and triggering is performed twice. I hope this can show you how for n signals to be triggerred, you can use n Trigger express VI's. There are various notes on the VI itself aswell as the screenshots. Remember that the code I have written is only an example, you must then modify it so that you can analyse your own signals correctly. If you would prefer, you can use the DAQmx Express VI to setup your signals, this is what i used in the previous version the Sample VI which i posted. Alternatively, you can use code similar to your orignal program 'Aquire Data....' and integrate the Trigger Express VI's into this code.

I hope this is of use and best wishes on your continued programming.

Many thanks

Rob

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