Siemens CPU 314 Reference Manual

CPUs
1-5
PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DP
A5E00111190-01
1.1.3 Backup battery/accumulator
Exceptions
The CPUs 312IFM and 313 do not have a real time clock so they do not need an
accumulator battery.
The CPU 312IFM does not have a buffer which means that you can not insert a
battery.
Backup battery or rechargeable battery?
Table 1-2 shows the differences in the backup provided by an accumulator and a
backup battery.
Table 1-2 Using a Backup Battery or Accumulator
Backup
with...
... Backs up Remarks Backup
Time
Rechargea
ble battery
Real-time clock only The rechargeable battery is charged
after CPU POWER ON.
Note
You must create a backup of the
user program either on Memory
Card or, in the case of CPU314IFM
314 (-5AE0x-), on EPROM.
120 h
(at 25C)
60 h
(at 60C)
... after 1
hour of
recharging
Backup
battery
 User program (if not
stored on memory card
and protected against loss
on power failure)
 More data areas in data
blocks are to be retained
than possible without
battery
 The real-time clock
Note
The >CPU can retain part of the
data without backup battery. You
only need a backup battery if you
want to retain more data than this.
1 year

Siemens CPU 314 Specifications

General

Brand	Siemens
Model	CPU 314
Category	Controller
Language	English