Siemens S7-300 Additional marginal conditions, Base load through Profibus devices, Tips and notes

Cycle and reaction times 5.2 Cycle time

Additional marginal conditions

The maximum cycle load through communication in the measurement is 20 %.

The lower graphic shows that the OB1 cycle is influenced by increasing the cyclical

PROFINET interconnections to remote partners at PROFINET:

Dependency of the OB1 cycle on the number of interconnections Cycle time in ms

14

12

10

8

6

4

2

0

OB1 cycle with 32 remote PROFINET partners

OB1 cycle with 5 remote PROFINET partners

0	32	64	96	128	160	200
		Number of interconnections

Base load through PROFIBUS devices

The 16 PROFIBUS devices with their interconnections among each other generate an additional base load of up to 1,0 ms.

Tips and notes

The upper graphic already includes the use of uniform values for the transfer frequency of all interconnections to a partner.

•The performance can drop by up to 50 % if the values are distributed to different frequency levels.

•The use of data structures and arrays in an interconnection instead of many single interconnections with simple data structures increases the performance.

CPU 31xC and CPU 31x, Technical data	5-13
Manual, Edition 08/2004, A5E00105475-05