Dchamberss

Dear Jack and EA Olson, Thanks so much for the replies. There is no substitute for experience and all of this is shrouded in the mists for me at this point. I actually "inherited" this code from a member of our research group who is now gone. As you can tell, she was no labview expert either. I've learned enough to understand the code and make it function, but elegant, LOL. No. To be honest I can hardly understand the first reply. I'm going to try to digest (understand) and use your suggestions. You guys have probably save me a week, so I just wanted say "Thanks" ASAP. Sincerely, David Keith Chambers Jack, thanks for the info, I'll check for that set bit to do the polling. I put the delay between the write/read so I could adjust the time in case the photodiode I'm testing needs time to establish a steady-state current, but otherwise, I need the code to run as fast as possible. If the responsivity is high enough, I'll want to do the measurements w/min delay here, using the polling method. I'll chew on this and post again if I have more problems.

Hey guys I've posted here before but couldn't access my account anymore. I would be greatly appreciative to anyone who cares to scrutinize my work and leaves a comment. I'm pretty new to labview and I don't have anyone I work with knows labview. I searched these forums (and Google) before posting. I think the Keithley 6487 is a commonly used instrument and I'm surprised not to see any discussion directly related (maybe I'm naive). Please 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 so the measurement isn't so slow, but I also want a time delay between the voltage write and current read 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!) David Keith Chambers Louisiana Tech University

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