System modifications during redundant operation
10.4 Removal of components
CPU 410-5H Process Automation
168 System Manual, 09/2014, A5E31622160-AB
Step 2: Modify and download the user program
Starting situation
The fault-tolerant system is operating in redundant system mode.
The following program modifications are not possible in redundant system mode and result
in the system mode Stop (both CPUs in STOP mode):
• Structural modifications to an FB interface or the FB instance data.
• Structural modifications to global DBs.
• Compression of the CFC user program.
Before the entire program is recompiled and reloaded due to such modifications the
parameter values must be read back into the CFC, otherwise the modifications to the block
parameters could be lost. You will find more detailed information on this topic in the
S7, Continuous Function Chart
manual.
1. Edit only the program elements related to the hardware removal. You can delete the
following components:
– CFCs and SFCs
– Blocks in existing charts
– Channel drivers, interconnections and parameter settings
2. In SIMATIC Manager, select the charts folder and choose the "Options > Charts >
Generate Module Drivers" menu command.
This removes the driver blocks that are no longer required.
3. Compile only the modifications in the charts and download them to the target system.
Note
Until an FC is called the first time, the value of
its output is undefined. This must be taken
into account in the interconnection of the FC outputs.
The fault-tolerant system continues to operate in redundant system mode. The modified user
program will no longer attempt to access the hardware being removed.
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