Communication Functions
8-23
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
Standard and H systems
The descriptions so far, apply to standard and H systems. Saturation is rarely
reached in todays plants because the communication performance of the standard
systems is substantially higher than that of the redundant H systems.
On the other hand, synchronizations are required for H systems to retain the
synchronous run. This increases the runtime of the block and reduces the
communication performance. This is why the performance limit is reached earlier.If
the redundant H system running has not reached the performance limit, the
approximate value of the performance will be less by factor 2 to 3 compared to the
standard system.
Which sizes influence the communication load?
The communication load is influenced by the following sizes:
• Number of connections /connected operator control and monitoring systems
• Number of variables and number of variables in pictures displayed via WinCC
or on OPs.
• Communication type(operator control and monitoring, S7 communication,
S7-messagefunctions, S5 compatible communication, ...)
• The extension of the configured maximun cycle via communication.
The subsequent section will show you the factors that influence the communication
performance.
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