Deliberate Delaying Of The Update; Performance Values For Link–Up And Update - Siemens SIMATIC S7-400H Manual

In the least favorable cases this period is extended by the following amounts:
• maximum watchdog interrupt cycle used
• duration of all watchdog interrupt OBs
• duration of high-priority interrupt OBs running up until delay of the interrupts

Deliberate delaying of the update

Delay the update via SFC 90 "H_CTRL" and do not release it again until a state of
lesser communication or interrupt load occurs.
Caution
!
Delaying the update will increase the time during which the fault-tolerant system is
in single mode.
6.3.4 Performance Values for Link–up and Update
User program share T
The user program share T
classes > 15 can be calculated using the following formula:
T
P15_AWP
The following table provides the resulting times for some typical values for the
main memory data.
Table 6-3
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
of the max. blocking time for priority classes > 15
P15_AWP
P15_AWP
in ms = 0,7 × size of the DBs in working memory in Kbyte + 75
Typical values for the user program share T
max. blocking time for priority classes > 15
Main memory data
500 Kbyte
1 Mbyte
2 Mbyte
Linking and Synchronizing
of the max. blocking time for priority
P15_AWP
of the
T
P15_AWP
430 ms
800 ms
1.51 s
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