Basics of program execution
7.3 Events and OBs
S7-1500R/H redundant system
156
System Manual, 10/2018, A5E41814787-AA
Table 7- 4
Response of S7-1500R/H redundant system when cycle time is exceeded with OB 80
Initial situation
1st time cycle time is ex-
ceeded
2nd time cycle time is ex-
ceeded
3rd time cycle time is ex-
ceeded
System Primary
CPU
Backup
CPU
System Primary
CPU
Backup
CPU
System Primary
CPU
Backup
CPU
System Primary
CPU
Backup
CPU
RUN-
Solo
RUN
STOP
RUN-
Solo
RUN +
OB 80
STOP
STOP
STOP
STOP
---
---
---
RUN-
Syncup
RUN-
Syncup
SYNCUP RUN-
Syncup
RUN-
Syncup
+ OB 80
SYNCUP
+ OB 80
1)
RUN-
Solo
RUN +
OB 80
STOP
STOP
STOP
STOP
RUN-
Redun-
dant
RUN-
Redun-
dant
RUN-
Redun-
dant
RUN-
Redun-
dun-
dant
RUN-
Redun-
dant +
OB 80
RUN-
Redun-
dant +
OB 80
RUN-
Solo
RUN +
OB 80
STOP
STOP
STOP
STOP
1)
OB 80 is not called until the cycle time is exceeded for the first time after the SYNCUP phase "Finish tasks".
Assignment between event source and OBs
The type of OB determines where you assign OB to event source:
●
For hardware interrupts: Assignment in hardware configuration
●
For all other OB types: Assignment when the OB is created, where applicable after you
have configured the event source
OB priority and runtime behavior
If you have assigned an OB to the event, the OB has the priority of the event. S7-1500R/H
CPUs support the priorities 1 (lowest) to 26 (highest). The following items are essential to the
execution of an event:
●
Call and execution of the assigned OB
●
The update of the process image partition of the assigned OB
The user program processes the OBs exclusively on a priority basis. This means the
program processes the OB with the highest priority first when multiple OB requests occur at
the same time. If an event occurs that has a higher priority than the currently active OB, this
OB is interrupted. The user program processes events of the same priority in order of
occurrence.
Note
Communication
Communication (for example test functions with the PG/PC) always operates with a priority
of 15. To avoid unnecessarily prolonging the program runtime in the case of time-critical
applications, make sure that these OBs are not delayed or interrupted by communication.
Assign a priority > 15 for these OBs.
Содержание Simatic S7-1500H
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