Siemens S7-300 appendix Reducing the response time with direct I/O access, = Longest response time

Cycle and reaction times 5.3 Response time

Calculation

The (longest) response time is the sum of:

Table 5-11 Formula: Longest response time

2 x process image transfer time for the inputs

+2 x process image transfer time for the outputs

+2 x program processing time

+2 × operating system processing time

+2 x program processing time

+4 x PROFINET IO update time (only if PROFINET IO is used.)

+4 x DP cycle time on PROFIBUS DP (only if PROFIBUS DP is used.)

+I/O delay

=Longest response time

Equivalent to the sum of 2 x the cycle time + I/O delay time + 4 x times the PROFINET IO update time or 4 x times the DP cycle time on PROFIBUS DP.

See also

Overview (Page 5-14)

5.3.4Reducing the response time with direct I/O access

Reducing the response time

You can reach faster response times with direct access to the I/O in your user program, e.g. with

•L PIB or

•T PQW

you can partially avoid the response times described above.

Note

You can also achieve fast response times by using process interrupts.

See also

Shortest response time (Page 5-16)

Longest response time (Page 5-17)

5-18	CPU 31xC and CPU 31x, Technical data
	Manual, Edition 08/2004, A5E00105475-05