Assembly of a CPU 41x–H
5.10 Overview of the parameters for the S7-400H CPUs
S7-400H
74 System Manual, 03/2012, A5E00267695-11
5.10 Overview of the parameters for the S7-400H CPUs
Default values
All parameters are set to factory defaults. These defaults are suitable for a wide range of
standard applications and can be used to operate the S7-400H directly without having to
make any additional settings.
You can determine the CPU-specific default values by selecting "Configuring Hardware" in
STEP 7.
Parameter blocks
The responses and properties of the CPU are defined in parameters which are stored in
system data blocks. The CPUs have a defined default setting. You can modify these default
setting by editing the parameters in the hardware configuration.
The list below provides an overview of the parameterizable system properties of the CPUs.
● General properties such as the CPU name
● Start-up
● Cycle/clock memory, e.g. the scan cycle monitoring time
● Retentivity, i.e., the number of bit memories, timers, and counters that are retained after
restart
● Memory, e.g. local data
Note: If you change the work memory allocation by modifying parameters, this work
memory is reorganized when you download system data to the CPU. As a consequence,
the data blocks generated by means of SFC are deleted and the remaining data blocks
are initialized with values from load memory.
If you change the following parameters, the work memory area available for logic blocks
and data blocks will be modified when loading the system data:
– Size of the process image, byte-oriented in the "Cycle/Clock memory" tab
– Communication resources in the "Memory" tab
– Size of the diagnostic buffer in the "Diagnostics/Clock" tab
– Number of local data for all priority classes in the "Memory" tab
● Assignment of interrupts (hardware interrupts, time delay interrupts, asynchronous error
interrupts) to the priority classes
● Time-of-day interrupts such as start, interval duration, priority
● Watchdog interrupts, e.g. priority, interval duration
● Diagnostics/clock, e.g. time-of-day synchronization
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