numeric integration

[heang]

Hello

What dt means in numeric integration vi? from the help, it is known that dt represents the step size in numerical method. if the input signal is 1000hz sampling rate, should i put the dt=0.001s?or i just leave it blank?

in a meantime, i have interpreted that the dt represents the interval time from initial t1 to final t2 (within the boundary which is to be integrated). yet i get a correct result. but if i set sampling rate to 5000 hz, the area i get is terribly showing erratic result

there are 2 peaks/spike everytime the signal is acquired. i need to find the area under each peak. so by using detect trigger vi, can extract both peaks to become 2  individual peak in graph. then numerical integration is done on each individual peak.
i can get the good result of 1000hz sampling rate.
but not the replica of 1000hz sampling rate.

what mistake i have done?

thanks
regards

[Dennis_Knutson]

From the help - dt is the interval size, which represents the sampling step size used in obtaining data in Input Array from the function. If you supply a negative dt, the VI uses its absolute value.

Sampling step size is 1/sample rate. Do not leave it blank. The default is 1.