There are three modes for parcentricity calibration:
Mode 1: This mode uses concentricity data from the fovcert.dat file. If a fovcert.dat file exists and it contains concentricity certification data, PC-DMIS uses this calibration mode.
Mode 2: This mode measures the series of circles, and it links together the circles in order to automatically correct for any concentricity error in the standard. If there is no concentricity data in the fovcert.dat file, and the ProbeQualVisionParCalibrationUseBridging entry (located in the USER_ProbeCal section of the Settings Editor) remains at its default setting of TRUE then this mode is used.
Mode 3: This mode measures the standard concentric circles and assumes they are perfectly concentric. If the fovcert.dat file doesn't contain concentricity data, and the ProbeQualVisionParCalibrationUseBridging entry is set to FALSE then PC-DMIS uses this calibration mode.
A related entry, ProbeQualVisionParCalibrationXYSamples, located in the same section of the Settings Editor, defaults to 3. This defines the number of times a given circle is measured at a given magnification during the parcentric high calibration.