Allen-Bradley controllogix 1756-L55M12, Руководство пользователя

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Publication 1756-UM001G-EN-P - January 2007
Develop Motion Applications 97
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 select New Motion Group.
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.
IMPORTANT
Add only one motion group for the project. RSLogix 5000 software does not let you
add more than one motion group.
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
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 cycle time of
the motion module.
Example: If the cycle time is 2 ms, set the coarse update
period to 8 ms, 10 ms, 12 ms, and so on.