Siemens S7-300 Shortest response time, Conditions for the shortest response time, Calculation

Cycle and reaction times 5.3 Response time

5.3.2Shortest response time

Conditions for the shortest response time

The figure below shows the conditions under which the shortest response time is reached.

Response time

CCP (OS)

PIO

PII

User program

CCP (OS)

PIO

Delay of inputs

Immediately before reading in the PII, the status of the monitored input changes. This change of the input signal is still included in the PII.

The change of the input signal is processed by the application program.

The response of the user program to the change of the input signal is issued to the outputs.

Delay of outputs

Calculation

The (shortest) response time is the sum of:

Table 5-10 Formula: Shortest response time

1 x process image transfer time for the inputs

+1 x process image transfer time for the outputs

+1 x program processing time

+1 × operating system processing time at the SCC

+I/O delay

=Shortest response time

The result is equivalent to the sum of the cycle time plus the I/O delay times.

See also

Overview (Page 5-14)

5-16	CPU 31xC and CPU 31x, Technical data
	Manual, Edition 08/2004, A5E00105475-05