Data Acquisition VI

[Dennis_Knutson]

Your graph should be showing those 100 samples unless you are getting an error. Probe the error wire or place an indicator there. You can easily get an error with continuous sampling and writing to a text file. This can be solved with a producer/consumer architecture or streaming to a binary file.

[dolakha]

Yes Sir, thank you very much for suggestions, I am feeling optimistic  after getting your prompt responses. My program does not shows error while running all the time but it sometime shows time value negative (x axis) , which consequences error in all the time value following it. what may be the cause .......It should increase  gradually upto the stoppage of test. Is it due to error in code?

[Dennis_Knutson]

I don't see anything obviously wrong in the last image you posted. I don't use express functions. Perhaps there is something wrong with the settings.

[dolakha]

Okay, Please suggest me if you find any thing else to support me. I have used kits only from mesuremetn I/O function.... I need to figure out the problem of  negative values in time axis as earlierly posted.

[Dennis_Knutson]

Create an indicator for the 1D waveform array or just probe the input to the write function. Check the settings of the express write. Try export waveforms to spreadsheet file.

[dolakha]

 Hello,

These days I am trying to add two more options on my front panel window like scanning and showing sample datas and adding zeros option so that i can start recording right from the instant of my interest.

sample output expected in front panel(scanning and displaying)

load                            2.2
stroke                  0.005
potentiometer 1         0.0004     all value needs to be changed with time.
potentiometer 2         0.0004

Your suggestions may contribute  a lot for me, I have attached
screenshot for your kind information.

[BobRodge]

Hi dolakha,

You can use the Get Waveform Components function in LabVIEW to obtain all of the signal data that is in the waveform data wire (the output from the DAQmx Read). You can then make indicators of the waveform components and have the numeric data displayed on the front panel.

I am not sure what you mean by adding zeros option. If you want this task to start when you want, you can put it in a Case Structure and wire a button to it. 

[dolakha]

Thanks, I am not done as it shows error while connecting 'get the waveform component' to the wire from Daqmx read data output, error says sth like data type not matched. I have to display 4 different items on front panel.

In the mean time, i want to clearify my earlier email, Zeros means i want to add a botton on front panal so that i can make some items like potentiometer 1& 2 reading equal to zero right before starting the test.

[BobRodge]

Hi dolakha,

Since the waveform data is an array, you could have to put it into an Index Array function first, then take each individual component into the Get Waveform Components function. 

As to the zeros, my recommendation would be to have the waveform data run through a Case Structure. Set up the Case Structure to output zeros in the waveform data when you press the button. Otherwise, the data goes through the false case and will act as normal.

[dolakha]

Dear Bob Rodge

I am greatly thankful to your timely response and valuable suggestions. Now i  came up with upgraded code which is preety close to our demand.All I need to do is to make all the reading except first one i.e load to be zero when i hit the zeros botton so that i can eliminate the human errors in potentiometer and all.Then i can enable the save botton to record datas.

 We all would be highly benifited if we came up with solution. I have attached screenshots for your reference. Thank you.