Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 161)

Section 4B
Connecting the 3-axis Servo Module
4B-15
Important: Battery backup is required for absolute encoders only.
Incremental encoders do not require battery backup.
The servo module provides battery backup for the absolute encoder
position register. This register retains position data during power loss.
The battery backup power originates from the batteries plugged into the
servo board at connector CN10.
Even if battery backup fails, or the encoder cable is temporarily
disconnected, the encoder will still maintain position data for up to 24
hours. This also allows for battery replacement without loss of data.
The battery backup is tested at power up, and at four hour intervals while
system power is on. If battery voltage drops to 2.8V during the battery
test, the control automatically displays the warning message “REPLACE
ABSOLUTE FEEDBACK BATTERY” on the operator panel.
Important: Once the “REPLACE ABSOLUTE FEEDBACK BATTERY”
message is displayed, it is essential that the batteries be replaced to avoid
loss of absolute position data.
To replace the servo module battery, turn all system power OFF and
disconnect the old batteries from CN10 on the servo module. Battery
replacement instructions are included with the battery replacement kit.
Before installing new batteries, use a voltage meter to make sure that new
battery voltage is higher than 3.5V dc.
Figure 4B.13
Digital Servo Module Battery Connector CN10
Servo Module
CN10
CN8
CN2
CN3
CN4
CN5
CN6
CN7
CN9
CN12
The lithium battery contains heavy metals and
must be collected separately from other waste.
4B.2.3
Servo Module Battery
Replacement