User manual

Rockwell Automation Publication MOTION-UM003F-EN-P - March 2015 83
Configure Axis Scheduling Chapter 3
Once an alternate rate is set on the Axis Schedule Panel, the Base Update
Period for the group on the Attribute tab becomes disabled. You can still
set the base update rate on the Axis Schedule Panel.
If you enter a value outside of that range, a warning appears and the value is
set to either 0.5 or 32, depending on if you entered too small or too large of
a value.
9. Choose the Alternate 2 update period.
If the base update rate is changed to a value that invalidates the alternate
update rates, a warning tool tip appears.
• If you click OK or Apply, a warning box appears that tells you that you
must select valid alternate update rates before you apply any changes.
10. Update the periods as required.
11. Click Apply.
TIP
If the Base Update Period is too small, the controller may not have time
to execute non-motion related ladder logic. Generally, the motion task
for the controller needs 1 millisecond per axis to have reasonable
execution time.
As a result, the configuration sets the lower limit on the Base Update
Period that is based on the number of axes in the group.