Battery Back-up During AC Power Loss
What if the Battery Dies?
In the event of AC power loss to the DL05 PLC, the on-board lithium battery will back-up the
program logic and data values for a period up to three years.
If the Memory Cartridge's battery voltage drops below
approximately 2.5VDC, the red "BATT" LED will illuminate on
the face of the module. At the same time, the Special Relay SP43 is
set to "1." You can use this internal bit as a contact in your ladder
program. Use it to trigger an external alarm – indicating that it is
time to change the battery.
During normal operation, the AC power to the PLC will retain the memory in the Memory
Cartridge. If the AC power fails, or is disconnected, a super-capacitor will continue to hold the
memory for 4 to 7 days even if the battery is too weak to hold the memory. Only after the
capacitor has discharged and the battery has become too weak to retain the memory will
program logic and data memory be lost.
Battery Type
When you see the "BATT" indicator light, replace the battery with a CR2032, coin-type 3.0V
lithium battery (Automationdirect.com, part no. D0–BAT). Do you need to change the battery
while retaining the stored program? If the answer is yes, change the battery during the 4 – 7 days
that the super-capacitor will retain the program after AC power is disconnected.
NOTE: Be sure your hands are clean and dry before handling the battery. Moisture will corrode the battery
surfaces and shorten the life of the battery.
Removing and Replacing the Battery
SP43
Y0
OUT
BATTERY
3V
To remove the battery:
Push the battery in the direction
indicated. You will feel the
battery press against the spring
in the battery socket. Fully
compress the spring and lift the
battery out of the socket.
DL05 Micro PLC User Manual, 6th Edition, Rev. A
Chapter 10: Memory Cartridge
Push
BATTERY
3V
To replace the battery:
The positive (+) side should be facing
out. The battery should enter the
socket as shown (at about a 30° angle
to the printed circuit board). Push the
battery into the socket until the battery
snaps into place.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
A
B
C
D
10–11
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