Hi all, I'm doing some automated low-current measurements and I may have some useful information for people in this thread. I don't have 6485, but higher model 6487 picoammeter, though.
At any rate, 6487 has internal buffer, which can store several hundreds measured values. It can be programed to do repeated measurements at certain time intervals and store the results in this buffer. Needless to say, access to the buffer is much faster than RS232 or GPIB. In the 6487 LabView driver, there are "multipoint" functions, which can set up these repeated measurements and then read the entire buffer at once.
And now about measurement speed: according to the 6487 manual, the instrument can take up to 1000 readings/second. However, such acquisition speed is possible only with low accuracy (resolution), with line filters turned off etc. In the default state, the 6487 has almost all these features turned on and set to achiveve high accuracy. But by turning them down, you can beef up acquisition speed. These things can be changed remotely, too. Of course, you will have to find some compromise between speed and accuracy, as needed in your applications.
Hope this helps.
