User manual

Rockwell Automation Publication MOTION-UM003F-EN-P - March 2015 185
Home an Axis Chapter 8
APR Fault Generation
An APR fault that is caused by a project download, restore from a CompactFlash
card, a restore from an SD card, or a ControlFLASH firmware update after one
of these events:
• Axis configuration
– Change in any of the axis attributes that impacts the absolute machine
position.
• Attribute changes
– Offline edits of the axis attributes or configuration does not cause an
APR fault until after download occurs.
– Online edits of certain attributes result in an immediate APR fault.
Changing the axis feedback device or feedback polarity without
downloading the project also generates an immediate APR fault.
• Axis hardware change or malfunction.
• Axis hardware resource insufficiency.
– Hardware resource insufficiencies are detected only during download
or ControlFLASH firmware update.
• Reconnection of the drive axis.
When an APR fault occurs, the actual position of the axis is set to the feedback
reference position of the axis. This value is read from the absolute encoder of the
axis. The APR Fault clears the axis homed status bit.
Downloading of a Project
The following checks are made during a download of a project.
1. Does the Axis already exist? If not, then it is a new axis and no APR fault
will ever result will ever get generated.
2. Does the Scaling Signature match the saved Scaling Signature?
3. Does the Feedback Serial Number match the saved Feedback Serial
Number?
If these three checks pass, generally absolute position is restored.
During operation, the system monitors changes to that following attributes,
which do not impact the Scaling Signature or result in the loss of the absolute
machine reference and therefore does not generate an APR Fault.
• Conversion Constant
• Position Unwind
• Trav e l Mod e