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

Structure of a CPU 41x
1.8

Overview of the Parameters for the S7-400 CPUs

Default Values
All the parameters have default settings at delivery. These defaults, which are
suitable for a whole range of standard applications, mean that the S7-400 can be
used immediately without the need for further settings.
You can find the CPU-specific default values using "Configuring Hardware" in
STEP 7.
Parameter Blocks
The behavior and properties of the CPU are defined using parameters that are
stored in system data blocks. The CPUs have a defined default setting. You can
change this default setting by modifying the parameters in the hardware
configuration.
The following list gives you an overview of the configurable system properties
available in the CPUs.
• General properties (e.g. Name of the CPU)
• Startup (e.g. enabling of a restart)
• Clock synchronous interrupts
• Cycle/clock memory (e.g. cycle monitoring time)
• Retentivity (number of memory markers, timers and counters that are
maintained)
• Memory (e.g.local data)
Note: If, for example, you set greater or smaller values than the default values
for the process image, the number of diagnostic buffer entries and the
maximum number of ALARM-8 blocks (SFB 34 and SFB 35) and blocks for S7
communication, the working memory available for the program code and for
data blocks will be reduced or increased by this amount.
• Assignment of interrupts (process interrupts, delay interrupts, asynchronous
error interrupts) to the priority classes
• Time-of-day interrupts (e.g. start, interval duration, priority)
• Watchdog interrupts (e.g. priority, interval duration)
• Diagnostics/clock (e.g. time synchronization)
• Protection levels
Note
16 memory bytes and 8 counter numbers are set to retentive in the default
settings, in other words, they are not deleted when the CPU is restarted.
1-24
Automation System S7-400 CPU Specifications
A5E00165965-01