how to acquire one sample at each rising edge on a I/O line till i stop a button

[mpsarma1]

usb 6211 is being used for data acquisition with labview 8.5 in windows xp.

how do i capture data at each rising edge on an i/o line till i stop.

[Nick_F1]

Hi mpsarama1,

There is an example program that will help you get started with what you want to do.  If you open the Example Finder (Help >> Find Examples...)  you can browse to Hardware Input and Output >> DAQmx >> Analog Measurements >> Voltage >> Cont ACQ&Graph Voltage-Ext Clk.vi.

This is an example that uses an external clock.  Basically what that means is that the example takes an external TTL signal, and on every rising edge of that signal a sample is taken.  The rate is used to setup the buffer and the samples to read is the number of samples that DAQmx will buffer before bringing the values into LabVIEW through the DAQmx Read.vi.  You will want to make sure and wire your signal into a PFI line and set the source on the DAQmx Timing.vi to that PFI line.  By default the example program has PFI7 set.

This example program will continue to run and acquire samples on the rising edge of the digital signal that you are sending in as a clock until you click on the stop button.  Please let me know if you have any questions about this example program.