Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
286
Writing and Executing Motion Programs
Rapid-Mode Moves
Rapid-mode moves provide for minimum-time point-to-point moves, subject to pre-defined motor
constraints. These moves are essentially jog moves for each motor assigned to an axis specified in the
move. The acceleration for each motor is controlled by the Ixx20 and Ixx21 acceleration times; however,
if the rate of acceleration determined by the motor’s move speed and these variables exceeds the Ixx19
acceleration limit, the times will be extended so that the rate will not exceed Ixx19. Many users will set
Ixx20 and Ixx21 to very small values (e.g. 1 and 0; do not set both to 0) so that the Ixx19 rate controls all
of these acceleration profiles.
constraints. These moves are essentially jog moves for each motor assigned to an axis specified in the
move. The acceleration for each motor is controlled by the Ixx20 and Ixx21 acceleration times; however,
if the rate of acceleration determined by the motor’s move speed and these variables exceeds the Ixx19
acceleration limit, the times will be extended so that the rate will not exceed Ixx19. Many users will set
Ixx20 and Ixx21 to very small values (e.g. 1 and 0; do not set both to 0) so that the Ixx19 rate controls all
of these acceleration profiles.
The speed of the move is controlled either by the maximum-speed parameter Ixx16 (default) or the jog-
speed parameter Ixx22, depending on the setting of motor variable Ixx90. A short move may not reach
the programmed speed, just accelerating and decelerating through the move.
speed parameter Ixx22, depending on the setting of motor variable Ixx90. A short move may not reach
the programmed speed, just accelerating and decelerating through the move.
A motion program is put into this mode using the RAPID statement. It is taken out of this mode by
another move mode command (e.g. LINEAR, CIRCLEn, PVT, SPLINEn). RAPID is equivalent to the
RS-274 G-Code G00.
another move mode command (e.g. LINEAR, CIRCLEn, PVT, SPLINEn). RAPID is equivalent to the
RS-274 G-Code G00.
Move Time
On a multi-axis rapid mode move, only the motor calculated to take the longest time at its specified Ixx16
or Ixx22 speed will actually be commanded to move at that speed. The commanded speeds for other
motors are lessened so that they have the same ratio of distance to speed, yielding the same move time for
all motors (before acceleration and deceleration are added). This makes the move path in a Cartesian
system approximately linear. However, if the acceleration times are not the same for all motors, as will
happen if the Ixx19 acceleration limits are hit, the commanded move path will not be perfectly linear.
or Ixx22 speed will actually be commanded to move at that speed. The commanded speeds for other
motors are lessened so that they have the same ratio of distance to speed, yielding the same move time for
all motors (before acceleration and deceleration are added). This makes the move path in a Cartesian
system approximately linear. However, if the acceleration times are not the same for all motors, as will
happen if the Ixx19 acceleration limits are hit, the commanded move path will not be perfectly linear.
Maximum Move Time Limit
The maximum move time for a RAPID-mode move is 8,388,607 msec, approximately 2 hours and 20
minutes. If the distance and speed for any motor request a move time greater than this time, Turbo
PMAC will use this maximum time instead, and the speed will be higher than what was programmed.
minutes. If the distance and speed for any motor request a move time greater than this time, Turbo
PMAC will use this maximum time instead, and the speed will be higher than what was programmed.
Minimum Move Time Limit
The minimum move time for a RAPID-mode move is the longest acceleration time (Ixx20 or 2*Ixx21,
whichever is greater) for any motor in the coordinate system, including motors not explicitly commanded
on the program line. Users who may command very short RAPID moves and want them to conclude very
quickly should set Ixx20 and Ixx21 very small for all motors, and use the Ixx19 acceleration limit to
control the acceleration profile.
whichever is greater) for any motor in the coordinate system, including motors not explicitly commanded
on the program line. Users who may command very short RAPID moves and want them to conclude very
quickly should set Ixx20 and Ixx21 very small for all motors, and use the Ixx19 acceleration limit to
control the acceleration profile.
Move Path
Because the move times (before accel/decel) for all motors are made the same, the move path in a
Cartesian system will be at least approximately linear. However, the acceleration times (not rates) for all
motors must be the same for a truly linear path in a Cartesian system. To obtain this fully linear path,
Ixx20 and Ixx21 must be the same for all motors in the coordinate system, and Ixx19 for all motors must
be set high enough not to be used for the move.
Cartesian system will be at least approximately linear. However, the acceleration times (not rates) for all
motors must be the same for a truly linear path in a Cartesian system. To obtain this fully linear path,
Ixx20 and Ixx21 must be the same for all motors in the coordinate system, and Ixx19 for all motors must
be set high enough not to be used for the move.
If kinematic subroutines are used to program a non-Cartesian system in Cartesian coordinates, RAPID-
mode moves will not in general have a linear path in the system. The kinematic calculations for RAPID-
mode moves are done only at the programmed end points for RAPID-mode moves, not at many points
along the way.
mode moves will not in general have a linear path in the system. The kinematic calculations for RAPID-
mode moves are done only at the programmed end points for RAPID-mode moves, not at many points
along the way.