Linking and Synchronizing
6-26
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
Table 6-3 Typical values for the user program share T
P15_AWP
of the
max. blocking time for priority classes > 15
Main memory data T
P15_AWP
5 Mbyte 3.66 s
10 Mbyte 7.24 s
The following assumptions were made for this formula:
• 80% of the data blocks are modified prior to delaying the interrupts of priority
classes > 15.
This value must be determined more accurately for fail-safe systems in
particular in order to avoid a time-out of the driver blocks (see Section 6.3.2).
• Approximately 100 ms of update time are allowed for each megabyte of working
memory assigned by data blocks for currently running or held-back
communication functions.
Depending on the communication load of your programmable logic controller,
you have to add to or deduct from the setting of T
P15_AWP
.
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