Removing/Replacing The Backup Battery - Emerson ControlWave Instruction Manual

ControlWave I/O Expansion Rack Instruction Manual

5.2.6 Removing/Replacing the Backup Battery

Caution
Removing /
Replacing the
Battery
5-12
For the backup battery to function, CPU switch SW3-4 must be
Note:
ON. See Section 2.4.1 for information on setting CPU module
switches.
The CPU module includes a backup battery that sits in front of the
PSSM module as you face the ControlWave I/O rack. The battery
provides backup power for the real-time clock (RTC), CMOS RAM,
and the system SRAM on the CPU module. The CPU module backup
battery is a 3.6V, 950 mA-hr ½ AA lithium cell battery.
: The CPU module draws power from the battery only if the
Note
module loses power. The system SRAM has a standby current
draw of 50 uA maximum for each part. For a ControlWave
containing 2MB of SRAM, a worst-case current draw of 110 uA
allows a battery life of approximately 8,636 hours. This means
you should not need to replace a battery until the ControlWave
has been in service for an extended period (normally many
years).
You lose SRAM contents when you remove the backup battery or its
assembly from the CPU module.
If you replace a backup battery or its assembly, wait at least one minute
before re-powering the system. This enables the SRAM to completely
discharge.
1. If the ControlWave I/O rack is running, place any critical control
processes under manual control.
Remove the bezel that covers the PSSM and CPU modules.
2.
3. Grasp the battery retaining clip and gently pull it up and away from
the backup battery assembly to release the top of the retaining clip.
Pull the retaining clip down and outward to remove it.
4.
5. Remove the battery. Wait at least one minute for SRAM to fully de-
charge.
Put in the replacement battery.
6.
7. Snap the retaining clip back into place.
Put the bezel back in place.
8.
Service & Troubleshooting Revised Aug-2015