Siemens SIMATIC S7-400H - Deliberate Delaying of the Update; Performance Values for Link-Up and Update

Linking and Synchronizing
6-25
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
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
P15_AWP
of the max. blocking time for priority classes > 15
The user program share T
P15_AWP
of the max. blocking time for priority
classes > 15 can be calculated using the following formula:
T
P15_AWP
in ms = 0,7 × size of the DBs in working memory in Kbyte + 75
The following table provides the resulting times for some typical values for the
main memory data.
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
500 Kbyte 430 ms
1 Mbyte 800 ms
2 Mbyte 1.51 s