Starting Up
6-13
S7-400 and M7-400 Programmable Controllers, Installation Manual
C79000-G7076-C424-01
6.8 Inserting a Backup Battery (Option)
Backup
Depending on the power supply module, you can use one or two backup batteries:
To back up a user program and save it without loss in the event of a power
failure.
For retentive storage of bit memory, timers, counters, and system data as well
as data in variable data blocks.
You can also provide this backup with an external battery (5 to 15 VDC). You
achieve this by connecting the external battery to the EXT. BATT. socket on the
CPU (see
Reference Manual
, Section 4.2). You can also back up modules in an
expansion rack via the EXT. BATT socket on the receive IM.
Inserting a Backup Battery
To insert the backup battery (batteries) in the power supply module, proceed as
follows:
1. Discharge any static charge by touching a grounded metal part of the S7-400.
2. Open the cover of the power supply module.
3. Insert the backup battery/batteries in the battery compartment.
Ensure correct polarity of the battery.
4. Switch on battery monitoring with the BATT INDIC slide switch, as shown in the
following table.
If You ... ...Then
have a single-width power supply module, set the BATT INDIC switch to BATT.
have a double or triple-width power supply
module and want to monitor a backup bat-
tery,
set the BATT INDIC switch to 1BATT.
have a double or triple-width power supply
module and want to monitor both backup
batteries,
set the BATT INDIC switch to 2BATT.
5. Close the cover.
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