Step 7, Step 2: Editing And Downloading The User Program; Step 7, Step 3: Stopping The Reserve Cpu - Siemens SIMATIC S7-400H System Manual

17.6.2

STEP 7, step 2: Editing and downloading the user program

Starting situation
The fault-tolerant system is operating in redundant system mode.
Restrictions
Any attempts to modify the structure of an FB interface or the instance data of an FB in
redundant system mode will lead to stop system mode (both CPUs in STOP mode).
Procedure
1. Edit only the program elements related to the hardware removal.
2. Download only the program changes to the target system.
Result
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.
17.6.3

STEP 7, step 3: Stopping the reserve CPU

Starting situation
The fault-tolerant system is operating in redundant system mode. The user program will no
longer attempt to access the hardware being removed.
Procedure
1. In SIMATIC Manager, select a CPU of the fault-tolerant system, then choose "PLC >
2. In the "Operating Mode" dialog box, select the reserve CPU, then click "Stop".
Result
The reserve CPU switches to STOP mode, the master CPU remains in RUN mode, the fault-
tolerant system works in single mode. The one-sided I/O of the reserve CPU is no longer
addressed.
S7-400H
System Manual, 03/2012, A5E00267695-11
CAUTION
You can add, edit or remove OBs, FBs, FCs and DBs.
Operating Mode" from the menu.
System modifications during operation
17.6 Removing components in STEP 7
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