User`s manual

7-34 Motion Mate™ DSM314 for Series 90™-30 PLCs User's Manual – January 2001 GFK-1742A
7
Jump Stop
A jump stop is a stop that is caused by a jump.
When a jump stop occurs, the current
programmed acceleration and acceleration mode are used.
Note that s-curve motion will
achieve constant velocity before beginning to decelerate. See the s-curve jump examples for more
details. There are two ways of generating a jump stop each described below.
A conditional JUMP triggered during a PMOVE will always generate a jump stop. Because a
PMOVE always stops before continuing to a subsequent motion, a jump stop always occurs when
a jump takes place during a PMOVE.
When a conditional jump trigger occurs during a CMOVE, however, a jump stop will not occur if
the motion programmed at the jump destination is a PMOVE or CMOVE representing sufficient
distance in the same direction. A jump stop will occur if the PMOVE or CMOVE at the jump
destination does not represent sufficient distance or represents motion in the opposite direction.
In an s-curve move, a jump stop will do one of two things. If the jump takes place after the
midpoint of the acceleration or deceleration, the acceleration or deceleration is completed before
the jump stop is initiated. If the jump occurs before the midpoint of the acceleration or
deceleration, the profile will immediately begin leveling off. Once acceleration or deceleration is
zero, the jump stop begins. See the s-curve jump examples.
Example 10: Jump Stop
The following is an example conditional jump with a jump stop. An enhancement on Example 5,
DWELL, would be to watch an external CTL bit that would indicate a problem with the positive
motion. If the CTL bit never turns on, the profile for the following program will be identical to
the profile shown in the DWELL example. If the CTL bit turned on during the first PMOVE or
the DWELL, the reverse movement would immediately commence.
The following profile would appear if the CTL bit turned on during the first PMOVE, at the
dashed line. Because the first move completed early due to the CTL bit turning on, the second
move would not have to move as far to get back to 0 position as it did in the DWELL example.
Note that because the motion programmed at the jump destination is in the opposite direction as
the initial motion, the profile would be identical if the moves were CMOVEs instead of PMOVEs.
ACCEL 30000
VELOC 15000
1: JUMP CTL09, 2
PMOVE 120000, ABS, LINEAR
DWELL 4000
2: PMOVE 0, ABS, LINEAR
Figure 7-13. Jump Stop
t
v
P
1
P2
C
TL09 ON