Reducing The Response Time With Direct I/O Access - Siemens CPU 31 Series Technical Data Manual

Calculation
The (longest) response time is the sum of:
Table 5-11
+
+
+
+
+
+
+
=
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 5-13)
5.3.4

Reducing 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 5-15)
Longest response time (Page 5-16)
CPU 31xC and CPU 31x, Technical Data
Manual, 01/2006 Edition, A5E00105475-06
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
Cycle and reaction times
5.3 Response time
5-17