User manual

Publication 1768-UM001C-EN-P - November 2007
Develop Motion Applications 91
Add the Motion Group
You can add a motion group to set up the motion planner.
To add a motion group to set up the motion planner, perform this procedure.
1. Choose your coarse update period.
2. In RSLogix 5000 programming software, right-click Motion Groups and
choose New Motion Group.
Motion Group Overview
Motion Planner Part of the controller that takes care of position and velocity information for your axes.
Coarse Update Period How often the motion planner runs. When the motion planner runs, it interrupts all other
tasks regardless of their priority.
Motion Planner
Scans of your code,
system overhead,
and so on.
0 ms 10 ms
20 ms 30 ms 40 ms
In this example, the coarse update period = 10 ms. Every 10 ms the controller stops scanning your code
and whatever else it is doing and runs the motion planner.
IMPORTANT
Add only one motion group for the project. RSLogix 5000
programming software does not let you add more than one
motion group.
IMPORTANT
The coarse update period is the interval between updating
your axes’ positions and scanning your code.
a. Set the coarse update period to 10 ms.
b. Leave at least half the controller’s time for the scanning of all
your code.
c. Set the coarse update period to a multiple of the motion
module’s cycle time.
Example: If the cycle time is 2 ms, set the coarse update
period to 8 ms, 10 ms, 12 ms, and so on.