Hello,
I've been using an example LabVIEW program such as Sweep and Acquirement to attain a simple I-V measurement. I am aware that 4-wire setup has a hard-limit on voltage of 21V without an interlock, and I only try to sweep up to 20V. However, somehow the voltage gets capped at the level less than 20V--somewhere 16V to 17V depending on a sample (I source voltage and measure current).
I instead tried the manual setting on the touchscreen. I changed the range from auto to 200V, and when I source 20V, the sourcemeter correctly puts 20V to the sample and displays a reasonable amount of current reading. Therefore, I assume the premature voltage cap that happens on LabVIEW implementation comes from the voltage range set as auto. However, I am still very confused as to why this is so. Why does it get capped below the hard voltage limit when the range is in auto mode? And, what kind of modification do I need in LabVIEW program to avoid this issue?