System modifications during operation
17.2 Possible hardware modifications
S7-400H
System Manual, 03/2012, A5E00267695-11
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Modifications to the user program and the connection configuration
The modifications to the user program and connection configuration are loaded into the
target system in redundant system mode. The procedure depends on the software used. For
more details refer to the
Programming with STEP 7 manual and the PCS 7, Configuration
Manual.
Note
After reloading connections/gateways, it is no longer possible to change from a RAM card to
a FLASH card.
Special features
●
Keep changes to a manageable extent. We recommend that you modify only one DP
master and/or a few DP slaves (e.g. no more than 5) per reconfiguration run.
●
When using an IM 153-2, active bus modules can only be plugged in if the power supply
is off.
NOTICE
Remember the following when using redundant I/O that you have implemented as one-
sided I/O at the user level (see section Other options for connecting redundant I/Os
(Page 207)):
Due to the link-up and update process carried out after a system modification, the I/O
data of the previous master CPU may be temporarily deleted from the process image
until all (changed) I/Os of the "new" master CPU are written to the process image.
During the first update of the process image after a system modification, you may
(incorrectly) have the impression that the redundant I/O has failed completely or that a
redundant I/O exists. So correct evaluation of the redundancy status is not possible until
the process image has been fully updated.
This does not apply for modules that have been enabled for redundant operation (see
section Connecting redundant I/O to the PROFIBUS DP interface (Page 177)).
Preparations
To minimize the time during which the fault-tolerant system has to run in single mode,
perform the following steps before making the hardware change:
●
Check whether the CPUs provide sufficient memory capacity for the new configuration
data and user program. If necessary, first expand the memory configuration (see section
Changing the CPU memory configuration (Page 329)).
●
Always ensure that plugged modules which are not configured yet do not have any
unwanted influence on the process.