Siemens SIMATIC S7-400 Manual page 16

Structure of a CPU 41x
2.1 Control and display elements of the CPUs
You need a cable with a 2.5 mm Ø jack plug to connect the power supply to the "EXT.-
BATT" jack, as shown in the following illustration. Make sure the polarity of the jack plug is
correct.
Figure 2-2
You can order a jack plug with an assembled cable from the Electronic Plant Karlsruhe
under the order number A5E00728552A.
Note
You require the external power supply to the "EXT.-BATT." jack when you replace a power
supply module and want to backup the user program stored in RAM and the data mentioned
above while you are replacing the module.
See also
Monitoring functions of the CPU (Page 2-5)
Status and error displays (Page 2-8)
Multipoint Interface (MPI) (Page 2-21)
2-4
Connecting Cable with Jack Plug
S7-400 Automation System, CPU Specifications
Manual, 10/2006, 6ES7498-8AA04-8BA0