Using sleep (or usleep from Time::HiRes) is how I've done it in the past, but the problem is accumulating time inaccuracy do to delays in processing.

For a bit more context, I'm taking measurements from electronic test equipment using the GPIB bus. I want to take those readings, say, every 10 seconds. The time it takes to tell the instrument to send a reading, for the instrument to process that request, and then return the result, is somewhat variable. So it's very hard to calibrate the sleep time to keep accuracy.

What I want to do is trigger the measurement cycle every X seconds regardless of how long (less than X, obviously) the measurement process takes.

In one previous iteration, I used HiRes gettime calls before and after the read/write cycle to determine how long the processing took, and used that to adjust the sleep time, but that seemed an awfully awkward way to go. I was hoping that a recurring alarm (which the HiRes setItimer function allows) would be a more elegant way to go.

Thanks! Hope this helps clarify.

In reply to Re^2: Waiting for Alarm by n8ur
in thread Waiting for Alarm by n8ur

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