Table 5-4 Types Of Memory Card - Siemens SIMATIC S7-400H System Manual

What type of memory card to use?
Whether you use a RAM card or a Flash card depends on your application.
Table 5-4
If you ...
also want to be able to edit your program in RUN, use a RAM card
want to keep a permanent backup of your user
program on the memory card when power is off,
i.e. without a backup battery or outside the CPU,
RAM card
Insert the RAM card to download the user program to the CPU. Download the user program
in STEP 7 by selecting "PLC > Download user program to Memory Card".
You can load the entire user program or individual elements such as FBs, FCs, OBs, DBs, or
SDBs to the load memory when the CPU is in STOP or RUN mode.
When you remove the RAM card from the CPU, the information stored on it will be lost.
The RAM card is not equipped with an integrated backup battery.
If the power supply is equipped with an operational backup battery, or the CPU is supplied
with an external backup voltage at the "EXT. BATT." input, the RAM card contents are
retained when power is switched off, provided the RAM card remains inserted in the CPU
and the CPU remains inserted in the rack.
FLASH card
If you use a Flash card, there are two ways of loading the user program:
● Use the mode selector switch to set the CPU to STOP. Insert the FLASH card into the
● Load the user program into the Flash card in offline mode on the programming
The FLASH card is a non-volatile memory, i.e. its data are retained when it is removed from
the CPU or your S7-400 is being operated without backup voltage (without a backup battery
in the power supply module or external backup voltage at the "EXT. BATT." input of the
CPU).
You always download the full user program to a FLASH card.
Downloading additional user program elements
You can download further elements of the user program from the programming device to the
integrated load memory of the CPU. Note that the content of this integrated RAM area will be
deleted if the CPU performs a memory reset, i.e. load memory is updated with the user
program stored on the FLASH card after a CPU memory reset.
S7-400H
System Manual, 09/2007, A5E00267695-03
Types of memory card
CPU, and then download the user program to the Flash card in STEP 7 by selecting
"PLC > Download user program to Memory Card".
device/programming adapter, and then insert the FLASH card into the CPU.
Installation of a CPU 41x–H
5.7 Structure and Functions of the Memory Cards
then ...
use a Flash card
55