Doubt Regarding Building VI

[sukumar]

And also this is with one another method. Here also the same problem that the signals are not coming correctly. And here there is no signal from the fourth channel itself. Can u pls solve me this problem. Thanks.

[EdDickens]

I'm going to have to say that there is a wiring problem somewhere. None of the VI's you have posted would cause the same signal to show up in the graphs.

Things to look for in the wiring. You have the DAQ assistant setup to read the signals as Differential signals. This means you should have a high side and a low side signal wire coming from each signal. For example, if you are using one of the standard NI terminal blocks, the signal for channel 0, the high side should be on terminal 68 and the low side should be on 34. Channel 1 should be high on 33, low on 66. Channel 2 should be high 65, low 31. Channel 3 should be high 30, low 63.

If these are all connected correctly, then you may have some cross talk in the wires going to the terminal block or a grounding issue some where else.

Check these and let us know what you find.

Ed

[sukumar]

those are not the differential signals. they all are different. I don't find any mistake in wiring since u may see its all clear, no overcrossings. And the same setup when I use with the other software that it comes with its working fine. Can u tell me what exactly could be the problem. Please once more have a look at it. Thanks

[Dennis_Knutson]

This whole thread seems to be pointless. You did not do what I asked in posting a VI with actual signals. Also, everyone who has looked at your VI has found nothing wrong with the code. If you have a problem with acquiring the signals, then it a problem with your configuration or the physical wiring.

[sukumar]

i have posted the VI. is that not the one u were asking for. I ran the program and stopped and then saved the file which I have posted earlier. what do u mean by posting VI for actual signals? Thanks.

[Dennis_Knutson]

You should carefully read what I asked before and I will repeat it - step by step. First, you need to add a graph for the un-split signal. This means adding an indicator right before the Split Signal function. Run the VI until you see a signal on the graphs. Now comes the important part and what you did not do before. Go to the Edit menu and select Make Current Values Default. Save the VI. Post it. It might be a good idea to close LabVIEW and re-open the VI before you post it. If there are no signals on the graphs, you did it wrong again.

[sukumar]

i dont see "make current values default" in the edit menu. I am using Labview 7.0. can u pls tell me where can i find it. Thanks.

[Dennis_Knutson]

In 7.0, it's under the Operate menu.

[sukumar]

hey here is the VI you asked for..waveform 9 is the unsplit signal. can u tell me now what's the problem would be? Thanks.

[Dennis_Knutson]

THERE IS NO PROBLEM. Each of the individual graphs is showing exactly the same signal that is on the graph with all 8. Do you not realize that each of the 8 graphs is autoscaling the y axis? Just look at the scale numbers on the y axis. Can you not tell that the graph with all 8 is going from .08 to -.04 volts and for example, waveform graph 4 is going from .03 to 0 volts? That's pretty basic. If you want the same scale for all channels, turn off autoscaling and set the y axis values to be the same on all 8.