Siemens SIMATIC S7-1500 System Manual page 103

Flexible automation concepts
8.3 Configuration control
Rules
Observe the following rules:
● The central configuration must not contain a CP/CM, e.g., no CM 1542-5 (DP master or
DP slave). You cannot load the configuration if you have configured a module of this type
and configuration control is enabled.
● If you have enabled configuration control, the CPU is not ready for operation without a
control data record. The CPU returns from startup to STOP if a valid control data record is
not transferred in the startup OB. The central I/O is not initialized in this case. The cause
for the STOP mode is entered in the diagnostics buffer.
● For addressing the WRREC instruction, use the HW identifier 33 (decimal, for the LADDR
block parameter) to write the control data record.
The HW identifiers can be found, for example, under PLC tags > Default tag table >
System constants or in the "System constants" tab in the Inspector window of the CPU.
● The control data record is saved retentively in the CPU, which means that it is not
necessary to write the control data record 196 again at a restart if the configuration is
unchanged. Prior to commissioning, we recommend that a memory reset be performed
for the CPU in order to delete any control data record that is present.
● Slot entries in the control data record outside the configured preset configuration are
ignored.
● The control data record can be shortened. It must contain the entries up to the last slot of
the current preset configuration.
● Each real slot may only be present once in the control data record.
● A real slot may only be assigned to one configured slot.
● System power supply modules (PS) can also be subject to configuration control. For a
system power supply module (PS) on slot 0, we recommended that you avoid
reconfiguration.
Note
Modified configuration
The writing of a control data record with a modified configuration triggers the following
automatic reaction by the CPU: Memory reset with subsequent startup with this modified
configuration.
As a result of this reaction, the retentively saved original data record 196 is deleted and
the new data record 196 is saved retentively.
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S7-1500 Automation System
System Manual, 02/2014, A5E03461182-AB