May 11, 2004

Automation v0.5

The sine generator works now! Special thanks to Dale Cigoy at Keithley for insisting that I could get down to a couple milliseconds per measurement. I'll post more information and the relevant files tomorrow morning, since some sorting needs to be done on the dependencies. For long waveforms (>100 points), I was running out of GPIB buffer, so I ended up rewriting the source generator to send batches of 25 points directly to the 6430, rather than building a huge command to send all at once. With basically everything optimized, sourcing current and measuring just voltage, I was able to achieve 1.8793 ms per measurement on average. This value seemed pretty stable, though, since I don't have an oscilloscope on hand, it is hard to tell whether this is the real value or if some measurements are faster than others. The timestamp resolution is around 1.9 ms.

For the following table, current, amplitude 1 μA, was sourced sinusoidally and 2500 points sent to the 6430.

scenarioavg time per measurement (ms)
everything off, measuring just voltage1.879
everything off, measuring all functions1.921

Alas when I tried to change the auto-zero I got a buffer read error. I'm not sure why.

Posted by torque at May 11, 2004 12:24 AM | TrackBack
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