Optimizing IV curve read/write on Keithley Picoameter

[Dchamberss]

Hey guys,

I've posted here before but couldn't access my account anymore (maybe I was purged? disgusting).

I want someone to look at my program structure and tell me if I've added the time delay in the right place and if there is a way to increase the speed I can run the measurement at or improve/optimize my coding (perhaps use the device's buffer ??). It seems the writes and read on the GPIB but are slowing down the measurement. Also, I put in the Voltage and Current frontpanel indicators, but they don't work (in real time).

I'm measuring the IV of photodiodes I fabricate (research). I use a Keithly 6487 Picoameter as the voltage source/measurement and current measurement unit. I'm also using a cornerstone (oriel) monochromator to shine different wavelengths of light on the diode. It's all set up on an optical table and both the Pico and the Mono are being run by GPIB. The hardworking tax-payers could only provide me with LabView7 express (for which I'm thankful).

So here's the basic experiment:

100 Shine a single color light on diode (set mono to desired wavelength, open shutter)

200 run an IV curves (step the voltage from A->B w/stepsize x, record measured current)

300 close the shutter

400 increase mono set point ( change the color/wavelength setting)

500 GOTO 100

REPEAT 100-500 over the desired wavelength range.

So this a basic nested loop (loop within a loop).

I want to optizmize the timing of the IV curve to the measurement isn't so slow, but I also want a time delay between the voltage write and current commands to give the device response a few hundered milliseconds to respond/stabilize.

And here's my code (IV-inner loop):

http://picasaweb.google.com/research.ifm/labview

Thanks Everyone for reading this and especially for any helpful comments (even critisism, I'm new so tell now!

Sincerely,

David Keith Chambers