Overview Of The Parameters For The S7-400 Cpus - Siemens SIMATIC S7-400 Manual

2.12

Overview of the parameters for the S7-400 CPUs

Default Values
When shipped all parameters are set to default values. These defaults are suitable for a
whole range of standard applications, in other words, an S7-400 can be used immediately
without requiring any further settings.
You can define CPU-specific default values using the "HW Config" tool in STEP 7.
Parameter Fields
The behavior and properties of the CPU are specified in the parameters that are stored in
system data blocks. The CPUs have a defined initial default status. You can modify this
default status by changing the parameters in HW Config.
The list below provides an overview of the selectable system properties of the CPUs.
● General properties, for example, the CPU name
● Startup, for example, enabling hot restarts
● Synchronous cycle interrupts
● Cycle/clock memory (e.g. scan cycle monitoring time)
● Retentivity, meaning the number of flags, timers and counters that are retained during a
● Memory, for example local data
S7-400 Automation System, CPU Specifications
Manual, 10/2006, 6ES7498-8AA04-8BA0
restart
Note: If you change the work memory allocation by modifying parameters, this work
memory is reorganized when you load system data to the CPU. The result of this is that
data blocks that were created with SFC are deleted, and the remaining data blocks are
assigned initial values from the load memory.
The usable size of the working memory for logic or data blocks is changed when loading
the system data if you change the following parameters:
– 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
2.12 Overview of the parameters for the S7-400 CPUs
Structure of a CPU 41x
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