S7-400 cycle and response times
19.9 Example of calculation of the interrupt response time
S7-400H
System Manual, 03/2012, A5E00267695-11
381
19.9
Example of calculation of the interrupt response time
Elements of the interrupt response time
As a reminder: The process interrupt response time is made up of:
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The process interrupt response time of the CPU
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The process interrupt response time of the signal module
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Twice the DP cycle time on PROFIBUS DP
Example: You have installed a 417-5H CPU and four digital modules in the central controller.
One digital input module is the SM 421; DI 16×UC 24/60 V; with process and diagnostic
interrupts. You have enabled only the process interrupt in your CPU and SM
parameterization. You decided not to use time-driven processing, diagnostics or error
handling. You have parameterized an input delay of 0.5 ms for the digital input modules. No
activities are required at the scan cycle checkpoint. You have set a cycle load of 20% due to
communication.
Calculation
In this example, the process interrupt response time is based on following time factors:
●
Process interrupt response time of CPU 417-5H: Approx. 0.3 ms (mean value in
redundant system mode)
●
Extension due to communication according to the description in section Interrupt
100 µs + 1000 µs × 20% = 300 µs = 0.3 ms
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Process interrupt response time of SM 421; DI 16×UC 24/60 V:
–
Internal interrupt processing time: 0.5 ms
–
Input delay: 0.5 ms
●
The DP cycle time on the PROFIBUS DP is irrelevant, because the signal modules are
installed in the central unit.
The process interrupt response time is equivalent to the sum of the listed time factors:
Process interrupt response time = 0.3 ms + 0.3 ms + 0.5 ms + 0.5 ms = approx. 1.6 ms.
This calculated process interrupt response time is the time between detection of a signal at
the digital input and the call of the first instruction in OB 4x.
Содержание SIMATIC S7-400H
Страница 24: ...Preface 1 1 Preface S7 400H 24 System Manual 03 2012 A5E00267695 11 ...
Страница 46: ...Getting Started 4 5 Special layout features of SIMATIC Manager S7 400H 46 System Manual 03 2012 A5E00267695 11 ...
Страница 120: ...Memory concept 10 1 Overview of the memory concept of S7 400H CPUs S7 400H 120 System Manual 03 2012 A5E00267695 11 ...
Страница 258: ...Communication 14 8 General issues regarding communication S7 400H 258 System Manual 03 2012 A5E00267695 11 ...
Страница 354: ...Synchronization modules 18 3 Selecting fiber optic cables S7 400H 354 System Manual 03 2012 A5E00267695 11 ...
Страница 434: ...Technical data 20 6 Runtimes of the FCs and FBs for redundant I Os S7 400H 434 System Manual 03 2012 A5E00267695 11 ...
Страница 460: ...Function modules and communication processors supported by the S7 400H S7 400H 460 System Manual 03 2012 A5E00267695 11 ...