124 Rockwell Automation Publication 1766-UM001O-EN-P - September 2021
Chapter 6          Real-Time Clock and Memory Modules
shows the status of the replacement battery. When the battery is low, the 
indicator bit is set (1). This means that the battery wire connector could be 
disconnected or if the battery is connected, the battery may be ready to fail in 
the next two weeks. In the latter case, the replacement battery needs to be 
replaced with a new one. When the battery low indicator bit is clear (0), the 
battery level is acceptable.
The Battery Low (BAT.LO) indicator on the LCD display of the controller also 
shows the status of the replaceable battery. When the battery is low, the 
indicator displays as a solid rectangle ( ). When the battery level is acceptable, 
the indicator displays as an empty rectangle ( ), as shown below.
If the RTC battery is low and the controller is powered, the RTC operates 
normally. If the controller power is removed and the RTC battery is low, RTC 
data is lost.
Memory Module Operation The memory module supports the following features:
• User Program, User Data, Datalog, and Recipe Back-up
• User Program Compare
• Data File Download Protection
• Memory Module Write Protection
• Removal/Insertion Under Power
User Program, User Data, Datalog, and Recipe Back-up
The memory module provides a simple and flexible program, data, DataLog, 
and Recipe transport mechanism, allowing the user to transfer the program, 
data, DataLog, and Recipe to the controller without the use of a personal 
computer and programming software.
The memory module can store one user program at a time.
During program transfers to or from the memory module, the controller’s 
RUN LED flashes.
ATTENTION: Operating with a low battery indication for more than 2 weeks may 
result in invalid RTC data unless power is on continuously.
COMM0
C
OM
M 
1
DCOMM
B
AT.
 L
O
U-
DI
SP
COMM
 
2
ATTENTION: Electrostatic discharge can damage the Memory Module. Do not 
touch the connector pins or other sensitive areas.