Acquire an analogue input data triggered by the high time and low time of a counter pulse

[nooobieee]

Hi All ,

    I'm trying to write a VI in the labview 8.1 version for testing sensors. The power to the sensor is pulsed And I need to get a value when the power to the sensor is ON and power to the sensor is OFF ( measure Max voltage when current is passing through the circuit and min voltage when no current is passing through) . My cycle is like 2 seconds ON and 8 seconds OFF.

And I want to acquire a reading in each of these states continuously. I'm able to use a counter pulse to do the pulsing but how can I tie this up with the data logging so can be sure that I'm logging in one data point in the ON state and one in the  OFF state?

Thanks

SJ

[johnsold · Accepted solution]

Acquire the pulse from the counter on an additional analog input channel.  When it is high your sensor is ON.

Lynn

[nooobieee]

Thank you , Okie now so I get the pulse in teh input line but How can I make sure that i log in a data point when it is On , so say maybe at at 1.5 sec(after it is ON) and then I want a datapoint in the low time , say like at the 5th second (once its off). so how can I trigger the data acquisition only at these times for every cycle?

[nooobieee]

by data point I mean the sensor response(voltage measurement) at these times.

[johnsold]

Let's create an example.  Suppose you sample each channel 10 times per second.  If the pulse goes high at the 17th sample, then log the sensor sample at i = 17 + 1.5 s * 10 S/s = 32.  Similarly the off sample would occur 50 samples after the falling edge of the pulse.

The timing is a simple process of sample rate and counting samples.

If your process generates much noise, take a subset of the samples near the time you want to record the data and average them together.

Lynn