User manual

38 Rockwell Automation Publication MOTION-UM003F-EN-P - March 2015
Chapter 1 Configure Integrated Motion Control Using Kinetix Drives
For the Kinetix 6500 drive, the minimum Base Update Rate is 1 ms.
Figure 1 - Base Update Period Example
The Base Update Period is a trade-off between updating positions of your axes
and scanning your code. In general, you do not want the Motion Task to take
more than 50% of the overall Logix controller time on average. The more axes
that you add to the Motion Group, the more time it takes to run the Motion
Ta sk .
For a 1756-L6x controller, the incremental impact on the Motion Task is roughly
2…3 drives/ms. For the 1756-L7x controller, the incremental impact on the
Motion Task is roughly at 6…8 drives/ms. Actual impact can vary depending on
axis configuration.
For detailed information on the Axis Scheduling function, Axis Assignment tab,
and Alternate Update Period Scheduling, see Configure Axis Scheduling on
page 77.
Integrated Architecture Builder
To help you determine motion system performance, use the motion performance
calculator in the Integrated Architecture Builder (IAB).
The IAB is a graphical software tool for configuring Logix-based automation
systems. It helps you select hardware and generate bills of material for
applications that include controllers, I/O, networks, PowerFlex drives, On-
Machine cabling and wiring, motion control, and other devices.
You can find the software at
http://www.rockwellautomation.com/en/e-tools/configuration.html
Motion Task
Scans of Your Code, System
Overhead, and so on
0 ms 10 ms
20 ms 30 ms 40 ms
In this example, the Base Update Period = 10 ms. Every 10 ms the controller stops scanning your code and whatever else it is doing and
runs the motion planner.