Sorry for the un-cleanness of the code. The calibrations are logged into HKLM\Software\SPC Rig\Calibrations under string names AmpMax and AmpMin. They vary the 4-20 mA scaling to "calibrate". HKLM\Software\SPC Rig\Calibrations is opened. The refnum is passed to Read Value to read AmpMax, its refnum is then passed to AmpMin, then the refnum is passed to Close Key. The missing Vi (?) is a linear scaling vi that it won't load because I saved it in 8.6.