Rockwell Automation Publication MOTION-UM003K-EN-P - January 2019 263
Homing Chapter 12
• The ControlLogix 5560 and GuardLogix 5560 series A controllers have
a battery to recover the position after a power cycle but does not support
APR.
• The ControlLogix 5560 and GuardLogix 5560 series B controllers
recover the position after a download or restore from CompactFlash
software card or a firmware update from the ControlFLASH™ software.
A battery is not required.
• The ControlLogix 5570 controller with a ControlLogix Controller
Energy Storage Module (ESM) works the same as the GuardLogix 5560
series B controller with a battery.
• The ControlLogix 5570 controller without a ControlLogix Controller
Energy Storage Module (ESM) works like a ControlLogix 5560 series B
controller without a battery.
Absolute Feedback Device
The absolute feedback device permits absolute position be retained through a
power cycle. These devices take various forms, but they can all maintain an
absolute feedback position while power to the drive and feedback device is off.
When power is turned back on, the drive reads the feedback referenced
absolute position from the feedback device. By applying a saved absolute offset
to this absolute feedback position, the motion control system can recover the
machine referenced absolute position.
Most drive products provide this capability. However, Absolute Position is lost
if the drive is swapped out or drive firmware is updated. Integrated motion on
the EtherNet/IP network lets you recover Absolute Position through power
cycles, program downloads, and firmware updates.
SERCOS Versus Integrated Motion on Ethernet Networks
For a SERCOS axis with absolute feedback, the drive scaling function and
absolute position are maintained in the drive. Therefore, the drive scaling
function and absolute position can be easily restored in the control after a
power cycle or download of a new project. This restoration is accomplished by
reading the position from the drive.
By contrast, an integrated motion on the EtherNet/IP network axis supports
controller-based scaling where absolute position is maintained in the firmware
of the controller. Without the work of the APR feature, absolute position
would be lost after a power cycle or project download.
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