S7-400 cycle and response times
19.8 Interrupt response time
S7-400H
380 System Manual, 03/2012, A5E00267695-11
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 41x–5H t
v
= 100 µs + 1000 µs × n%, significant extension possible
where n = cycle load due to communication
Signal modules
The process interrupt response time of signal modules is made up as follows:
● Digital input modules
Process interrupt response time = internal interrupt processing time + input delay
You will find these times in the data sheet for the respective digital input module.
● Analog input modules
Process interrupt response time = internal interrupt processing time + conversion time
The internal interrupt processing time for analog input modules can be neglected. The
conversion times can be found in the data sheet for the individual analog input modules.
The diagnostic interrupt response time of the signal modules is the time from detection of a
diagnostic event by the signal module to the triggering of the diagnostic interrupt by the
signal module. This short time can be neglected.
Hardware interrupt processing
Hardware interrupt processing begins when the process interrupt OB4x is called. Higher-
priority interrupts stop process interrupt processing. Direct access to I/O modules is
executed during the execution time of the operation. After the process interrupt has been
processed, the system either resumes cyclic program processing, or calls and processes
interrupt OBs of the same or lower priority.
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