Siemens S7-400 installation manual Inserting a Backup Battery Option

Commissioning

6.8Inserting 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, CPU Data Section 1.2). 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	set the BATT INDIC switch to 1BATT.
module and want to monitor
a backup battery,
have a double or triple-width power supply	set the BATT INDIC switch to 2BATT.
module and want to monitor both backup
batteries,

5. Close the cover.

Automation System S7-400	Hardware and Installation	6-13
A5E00850741-01