time based recording

[tata245]

I want to record data to a file while the measured values are running,going on screen.For now I only successed to record data for a specific time period but also the measurement loop stops when the record time stops.How can I do a vi in which the measurement goes on without depending on time and whenever I want to start the recording I push  a button and the recording for a specific time period starts?Please help I feel desperate

[RTSLVU]

.

[tata245]

Hi,
Thank you for your answer but I want to start this recording action with a record button I cant figure out how to do this? How can I do it?

[mikeporter]

The code has a number of issues, like the express VIs and using the wrong timing functions, but beyond that it looks like you are wanting to read a new data point every 100ms for some period of time and then stop. Yes?

Why are you reading the points individually? 100ms equates to a 10 Hz sample rate. Assuming you are wanting to acquire data for 10 seconds, that's 1000 datapoints. So configure the daq to acquire 1000 points at a 10 Hz sample rate, and you're done -- the timing is exact, and no loops.

Mike...

[tata245]

Actually its an encoder measurement.I located a simulate signal on purpose instead of DAQ.So I want to measure RPM with an encoder so record these data to a file.

Considering these how can I trigger recording with a record button?

[tata245]

it doesn't work ,time limitation continues with the while loop so it does't limit the recording time.Every time it reaches the target time it starts again from zero time.

[mikeporter]

There's two things wrong. The program structure, but also the way you are doing the measurement. You need to be using a counter, configured as an interval counter -- check the examples that ship with LV. Get that going correctly and we can talk about program structure. No Express VIs. It's time to take off the training wheels.

Mike...