Mitsubishi Electric QD77MS User Manual page 506

POINT

When the "reference axis speed" is set during 4-axis linear interpolation control,
set so the major axis side becomes the reference axis. If the minor axis side is set
as the reference axis, the major axis side speed may exceed the "[Pr.8] Speed
limit value".
 Refer to Section 9.1.6 "Interpolation control" for the reference axis and
interpolation axis combinations.
Chapter 9 Major Positioning Control
9 - 48