Pcs7, Step Ii: Changing And Loading User Program - Siemens SIMATIC S7-400H Manual

Modifications to the System while in Operation
10.3.2

PCS7, Step II: Changing and Loading User Program

Initial situation
The fault-tolerant system is working in the Redundant system mode.
Caution
!
The following program modifications are not possible in the 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, since otherwise the
modifications to the block parameters could be lost. More details of this can be
found in the manual CFC for S7, Continuous Function Chart .
Procedure
1. Perform only the program modifications relating to the hardware to be
removed. You can remove the following components:
– CFC and SFC charts
– blocks in existing charts
– channel drivers, connections and parameterizations
2. In SIMATIC Manager select the charts folder and select the menu command
Extras > Charts > Generate module drivers.
This removes the driver blocks that are no longer required.
3. Compile only the modifications in the charts and load these into the PLC.
Note
Until the first FC is called the value of its output is undefined. This is to be taken
into account in the connection of the FC outputs.
Result
The fault-tolerant system continues to work in the Redundant system mode. The
modified user program will no longer attempt to access the hardware to be
removed.
10-18
S7-400H Programmable Controller Fault-Tolerant Systems
A5E00068197-04