Siemens SIMATIC S7-400H System Manual page 282

S7-400 cycle and reaction times
16.8 Interrupt reaction time
Signal modules
The process interrupt reaction time of signal modules is made up as follows:
● Digital input modules
● Analog input modules
The diagnostic interrupt reaction 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
module. This time is negligible.
Process interrupt handling
Process interrupt processing is initiated with the call of process interrupt OB 4x. Higher-priority
interrupts interrupt process interrupts processing, and direct access to the I/O is made when
the instruction is executed. After the process interrupt has been processed, the system either
resumes cyclic program execution, or calls and processes interrupt OBs of the same or
lower priority.
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Process interrupt reaction time = internal interrupt processing time + input delay
For information on times, refer to the data sheet of the relevant digital input module.
Process interrupt reaction time = internal interrupt processing time + conversion time
The internal interrupt processing time of the analog input modules is negligible. For
information on conversion times, refer to the data sheet of the relevant analog input
module.
System Manual, 09/2007, A5E00267695-03
S7-400H