4. Motion Control Instructions If there are multiple rows of codes and E and F in G2 code are omitted, the velocity, acceleration, deceleration of the cutter are based on E and F in the previous rows of codes before the row where G2 is. If the previous rows of G codes have not specified E and F, “maximum velocity”, “maximum acceleration”, “maximum deceleration” in the parameters of X axis will be taken as reference. In absolute mode for G90, the terminal point of circular arc is the absolute coordinate value regarding 0 unit in their own directions as reference. In relative mode for G91, the terminal point of circular arc is the incremental value of the start point of circular arc.
No matter whether in the absolute mode or in relative mode, the coordinates of the center of a circle I_J_(I_K_/J_K_) are always the relative coordinates with the start point as reference T is the quantity of one full circle; the path is the length of the arc when T=0; the path is the corresponding full circles plus the arc length when T is a constant. The difference between Format 2 and format 1 is that format 2 determines a segment of the circular arc via the start point, terminal point and radius.
If the input value to the right of R parameter is positive number (R+), the circular arc is the minor arc less than 180 degrees; if the input value to the right of R parameter is negative number (R-), the circular arc is the major arc more than 180 degrees. The following full lines are the motion path when G3 selects R+ and R- and the arrows on the arc refer to the motion direction. The coordinate relations on different planes:
Y Z Z Start point Start point Start point Terminal point Terminal point Terminal point Ce nter of a circle Ce nter of a circle Ce nter of a circle O O O a) XY plane circular arc b) XZ plane circular arc C) YZ plane circular arc X X Y Please note the relations between the coordinate planes and I, J, K. Only two of I, J and K exist in one circular arc instruction. Which two exist depends on the corresponding plane, e.g. on XY plane, only I and J show. The coordinate plane can be set by G17, G18 and G19. The circular and helical motion paths for G3 on different coordinate planes are shown as below. 4-202 DVP-MC operating manual J I K l K J