Two signals at two waveform graphs

Hello Everyone!
I got some problems with my software for data acquisition.
I got two signals and I have to show two signals at two different Waveform Graph.
How to seperate signals?
Solved!
Go to Solution.
Attachments:
separate.png ‏37 KB
spearate.vi ‏23 KB

I read DAQmx help and what I know is that Each row corresponds to a channel in the task. Each column corresponds to a sample from each channel.
I really don't know how to wire Index Array... Can you explain it to me, please?
Look at the attachment, is it ok?
Attachments:
explain.png ‏8 KB

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Thanks for your help and for sending the demo.
I understand the concept of how the signals will look if they're not synchronised and your demo shows that nicely. I guess I have been perplexed by someone else telling me that the timestamps in the output file (and following from that I assume timestamps on a waveform graph) do not give an indication of whether signals are synchronised. The reason they gave for this was that the timestamps are manufactured by the software, not the DAQ hardware. They suggested that I put the setting "ignore waveform timestamps" on my waveform graphs, and then check that both signals come in at the same time (i.e. both start at zero), but I'm not convinced about this.
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Thanks for the response Dennis.
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How can I get extract the data between two cursors on an XY graph

How can I get extract the data between two cursors on an XY graph

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hey, sorry for this question i think that the answer ei very simple.
I generate a squared signal with labview Vi in a fpga and with a Compact RIO module.
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Hi,
To have information abourt this forum, refer to this link:
http://forums.ni.com/ni/board/message?board.id=4170&message.id=9244#M9244
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Hello LabView Gurus,
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Attachments:
v603.png ‏320 KB
v603.vi ‏186 KB

Jeff Bohrer wrote:
Basic math gives me a bit of pause on this approach. You are sampling at 50 times the frequency of interest so you get 50 samples per cycle. your phase resolution is 1/50th cycle or 7.2 degrees +/- noise. You will need to samlpe faster to reduce phase resolution or average multiple readings (at a time cost that is signifigant)
Jeff- (Hardly Working)
I am sampling at 100 times the sine wave's frequency and 200 times the square wave's frequency. Increasing the sampling rate completely solves my problem. But since I am acquiring several other inputs, I cannot afford a sampling rate higher than 5kHz.
F. Schubert wrote:
I'm not a signal processing expert, but here my basic understanding.
If you simulate sampling with 5kHz and a frequency of 50 Hz (and both are 'sync' by design), you always get an exact 5 periods. Any variation of your signals frequency gives you a propability to get 4 or 6 'trigger' events. That's an up or down of 20%!
The one measure to reduce such problems is using 'window functions'. They don't fit your current approach (counting instead of a DSP algorithm), so this needs to be reworked as well.
My approach would be to use the concept of a Locki-In amplifier. You need to phaseshift your ref-signal by 90°. Then multiply your measurement signal with the ref signal and the phase shifted ref signal. The obtained values for x/y coordinates of a complex number. Calculate the theta of the complex number (with the LV prim). Feed this in a low pass filter.
The trick on this is, that the square wave has harmonics in it, in this you are interested in the second harmonic which is the sine wave.
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I suggest you to check on wikipedia for some of the keywords I mentioned. Go also for the external links which lead to great tutorials and AppNotes on the signal processing basics.
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Felix
www.aescusoft.de
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An interesting view. the sine wave can indeed be looked as a second harmonic of the square wave. I will implement your idea and get back to you as soon as I get some results. But since I have very limited knowledge of signal processing, it might take me a while to get my hear around the solution you mentioned.

How do you add two separate treadlines to a graph

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You have to have the proper Table layout for this to work.
Numbers requires that the two different series be in different pairs of columns.
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Message was edited by: Jerrold Green1

Two signals at two waveform graphs

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