Interrupt Response Time - Siemens SIMATIC PCS 7 CPU 410-5H System Manual

15.15.7

Interrupt response time

Definition of interrupt response time
The interrupt response time is the time from the first occurrence of an interrupt signal to the
call of the first instruction in the interrupt OB.
General rule: Higher priority interrupts are handled first. This means the interrupt response
time is increased by the program execution time of the higher-priority interrupt OBs, and by
previous interrupt OBs of the same priority which have not yet been processed (queue).
Note that any update of the standby CPU extends the interrupt response time.
Calculating the interrupt response time
Minimum interrupt response time of the CPU
+ minimum interrupt response time of the
signal modules
+ cycle time on PROFIBUS DP or PROFINET IO
= Shortest interrupt response time
Minimum interrupt response time of the CPU
+ maximum interrupt response time of the
signal modules
+ 2 * cycle time on PROFIBUS DP or PROFINET IO
= Longest interrupt response time
Hardware and diagnostic interrupt response times of the CPUs
Table 15- 19 Hardware and interrupt response times; maximum interrupt response time without com-
CPU
CPU 410-5H stand-alone mode
CPU 410-5H redundant
Increasing the maximum interrupt response time with communication
The maximum interrupt response time is extended when the communication functions are
active. The additional time is calculated using the following formula:
CPU 410-5H t
where n = cycle load due to communication
CPU 410-5H Process Automation
System Manual, 09/2014, A5E31622160-AB
munication
Hardware interrupt response
times
min.
60 µs
140 µs
= 100 µs + 1000 µs × n%, significant extension possible
v
15.15 Cycle and response times of the CPU 410-5H
Diagnostic interrupt response
times
max. min.
90 µs 60 µs
310 µs 120 µs
Supplementary information
max.
90 µs
250 µs
317