Siemens SIMATIC S7-300 CPU Data: CPU 315-T-2 DP User Manual

Cycle and response times
7.5 Interrupt response time
Calculation
The formulae below show how you can calculate the minimum and maximum interrupt
response times.
Table 7-8 Process/diagnostic interrupt response times
Calculation of the minimum and maximum interrupt reaction time
Minimum interrupt reaction time of the CPU
+ Minimum interrupt reaction time of the
signal modules
+ DP cycle time on the PROFIBUS DP
= Quickest interrupt reaction time
Maximum interrupt reaction time of the CPU
+ Maximum interrupt reaction time of the signal
modules
+2 x DP cycle time on the PROFIBUS DP
The maximum interrupt reaction time is longer when
the communication functions are active. The extra
time is calculated using the following formula:
tv: 200 μs + 1000 μs × n%
Significant extension possible with n = cycle time
extension through communication
Signal modules
The process interrupt response time of signal modules is determined by the following factors:
• Digital input modules
Process interrupt response time = internal interrupt preparation time + input delay
You will find the times in the data sheet of the digital input module concerned.
• Analog input modules
Process interrupt response time = internal interrupt preparation time + conversion time
The internal interrupt processing time of the analog input modules is negligible. The
conversion times can be taken from the data sheet of the analog input module
concerned.
The
diagnostic interrupt response time of signal modules is equivalent to the period that
expires between the time a signal module detects a diagnostic event and the time this signal
module triggers the diagnostic interrupt. This time is so small that it can be ignored.
Process interrupt processing
When the process interrupt OB 40 is called, the process interrupt is processed. Interrupts
with higher priority interrupt process interrupt processing and direct access to the I/O is
made when the statement is executed. When process interrupt processing is completed,
either cyclic program processing is continued or other interrupt OBs with the same or a lower
priority are called and processed.
S7-300 CPU Data: CPU 315T-2 DP
7-16 Manual, 12/2005, A5E00427933-02

Siemens SIMATIC S7-300 CPU Data: CPU 315-T-2 DP Specifications

General

Brand	Siemens
Model	SIMATIC S7-300 CPU Data: CPU 315-T-2 DP
Category	Control Unit
Language	English