Changing The Type Of Load Memory - Siemens SIMATIC S7-400H Manual

11.7.2

Changing the Type of Load Memory

The following types of memory cards are available as load memory:
• RAM card for the test and commissioning phase
• FLASH card for the permanent storage of the finished user program
The size of the new memory card is irrelevant here.
With this type of memory modification no program segments are transferred from
the master CPU to the standby CPU, only the contents of the blocks in the user
program that remain unchanged (see Section 6.2.3).
It is the user's responsibility to load the entire user program into the new load
memory.
Initial situation
The fault-tolerant system is working in redundant system mode.
The current status of the user program is available on the PG/ES as a STEP 7
project in modular form.
Caution
!
You cannot use a user program loaded from the PLC here.
It is not permissible to recompile the user program from an STL source file since
then all the blocks will be given a new time stamp. No block contents will then be
copied on master/standby switch-over.
Procedure
Perform the steps below in the order specified:
Step What Has To Be Done?
1 Switch the standby CPU to STOP mode using
the PG.
2 Unplug the existing memory card from the
standby CPU and plug in a memory card of
the desired type.
3 Reset the standby CPU using the PG.
4 Load the user program and the hardware
configuration into the standby CPU.
5 Start the standby CPU by means of the menu
command PLC > Mode > Switch to CPU
with... modified configuration.
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
Modifying the System During Operation
How Does the System React?
The system is working in single mode.
Standby CPU requests reset.
–
–
•
Standby CPU links up, is updated and
becomes the master.
•
Previous master CPU goes into STOP.
•
System works in single mode.
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