sychronization with the real time signal

[kanya]

dear sir,

    i am using scxi1125 card to get the anolog signal from the real system.i just do the operation of zerocrossing in labview and sent the output through the printer port of the computer.when i compare my input signal and the zerocrossed output from the printer port its doesnt match with the frequency of the input sine signal. there is more delay between the input and output.

    so if i want to acquire the data ,process it and to control it what i have to do?

[TheWoost]

Hi kanya,

When you initially bring the data in from the analog input task, are you bringing in raw samples or the waveform datatype (which includes timing information)?  My guess is that the writing of the processed data to the printer port is software timed and is not synchronized properly with the input signal.  If you have the SCXI-1180 feedthrough module to provide access to the digital output lines of your communicating DAQ device, doing a digital output task rather than printer port output would probably be more in line with what you want.

Regards,
Andrew W
National Instruments