Siemens SIMATIC S7-400H Manual page 130

Modifications to the System while in Operation
Loaded data blocks must not be cleared and generated again, i.e. the SFCs 22
(CREATE_DB) and 23 (DEL_DB) may not be applied to DB numbers occupied
by loaded DBs.
Make sure that at the time the system modification is made on the PG/ES the
current status of the user program is still available as a STEP 7 project in
modular form. It is not sufficient for the user program from one of the CPUs to
be loaded back into the PG/ES or compiled again from a STL source file.
Modification of the hardware configuration
With a few exceptions, all segments of the configuration can be modified while in
operation. As a rule, a configuration modification also results in a modification in
the user program.
The following must not be modified:
certain CPU parameters (for details refer to the relevant subsections)
the transmission rate (baud rate) of redundant DP master systems
S7 and S7H connections
Modifications to the user program and the connection configuration
The modifications to the user program and the connection configuration are loaded
into the PLC in the Redundant system mode. The procedure depends on the
software used. For more details refer to the manuals under Programming with
STEP 7 V5.1 und PCS 7, Configuration Manual .
Special Features
Do not carry out more modifications than you can keep an overview of. We
recommend that you modify only one DP master and/or a few DP slaves (e.g.
no more than 5) per reconfiguration run.
During routine operation, you can add or remove modules in DP stations with a
redundant PROFIBUS-DP interface module only with the interface modules
IM 153-2, IM 153-2FO or IM 157 specified in Section 6.3.
In the case of IM 153-2 bus modules can only be plugged in is the power supply
is interrupted.
10-4
S7-400H Programmable Controller Fault-Tolerant Systems
A5E00068197-04