Siemens CPU 31 Series Technical Data Manual page 148

Technical data of CPU 31xC
6.6 Technical data of the integrated I/O
Figure 6-4
In the two graphics below we illustrate how the 50 Hz and 60 Hz interference suppression
work
Figure 6-5
6-36
Principle of interference suppression with STEP 7
50 Hz interference suppression
CPU 31xC and CPU 31x, Technical Data
Manual, 01/2006 Edition, A5E00105475-06