Siemens SIMATIC S7-400H System Manual page 51

You can order an assembled jack connector and cable with the order number
A5E00728552A.
Note
If you replace a power supply module and want to backup the user program and the data (as
described above) in an RAM while doing so, you must connect an auxiliary power supply to
the "EXT. BATT." socket.
Do not interconnect the cables of different CPUs. Interconnecting the cables of different
CPUs may lead to problems with regard to EMC conditions and different voltage potentials.
S7-400H
System Manual, 03/2012, A5E00267695-11
5.1 Operator controls and display elements of the CPUs
Assembly of a CPU 41x–H
51