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S5-115U Manual
Example of interrupt OB (OB2, OB3, OB4, OB5)
9.2
Calculating Interrupt Response Times
The total response time is the sum of the following:
•
Signal delay of the interrupt-initiating module (=time from interrupt-initiating input signal
change until activation of the interrupt line)
•
Interrupt response time of the CPU
•
Execution time of the interrupt program (=sum of all STEP 5 operations in the interrupt-
evaluating program).
Calculate the interrupt response time of the CPU as follows:
Interrupt response time of the CPU=Basic response time+additional response times
The basic response time is 0.4 to 0.9 ms in the case of CPUs with one interface and 0.4 to 1.4 ms in
the case of CPUs with two interfaces and applies when
•
Integral FBs have not been used
•
The integral clock has not been initialized
•
PG/OP functions are not pending
•
No computer link ((3964R) procedure) and no ASCII driver is active
•
Time-controlled OBs are not programmed
and
•
SINEC L1 is not connected.
See Table 9-1 for the additional response times which can vary.
EWA 4NEB 811 6130-02b
Save flag contents
Identify interrupt-initiating
module or interrupt
initiating channel,
acknowledge interrupt
Interrupt response
Transfer saved flag contents
back
Figure 9-1. Program for Interrupt OB (Principle)
Interrupt Processing
9-3
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