User manual

260 Rockwell Automation Publication MOTION-UM003F-EN-P - March 2015
Appendix C Program
Depending on the instruction’s Speed parameter, the same ‘% of time’ jerk can
result in different slopes for the acceleration profile than on the deceleration
profile.
The motion planner algorithm adjusts the actual jerk rate so that both the
acceleration profile and the deceleration profile contain at least the ‘% of time’
ramp time. If the Start Speed is close to the programmed Speed parameter, the
actual percentage of ramp time can be higher than the programmed value.
In most cases, the condition is:
if: (start Speed is == 0.0) OR (start Speed is > 2 * max Speed)
then: you get programmed percentage of ramp time
else: you get higher than programmed percentage of ramp time
Conversion from% Time to Engineering Units
If you want to convert % of Time to Engineering Units, use these equations.
For Accel Jerk:
Speed
Jerk
Deceleration
60% of Time
j
a
[% of Time] =
1 +
100
2
j
a
[EU/s
3
] v
max
[EU/s]
a
max
[EU/s
2
]