Siemens SIMATIC S7-300 Product Information page 96

Basic functions
4.1 Encoder settings
Multiturn information (parameter 421 in the drive)
The multiturn information contains the number of full encoder revolutions.
With each complete revolution of the encoder, the multiturn information is incremented by
one. If the maximum data width of the multiturn information is achieved, the encoder actual
value is reset to zero.
Encoder pulses per revolution (parameter 408 in the drive)
The encoder pulses per revolution is the characteristic parameter of the encoder. It defines
the number of encoder tallies per revolution. For analog encoders, it specifies the number of
sine / cosine oscillations per revolution. Optical encoders have tallies which are etched on a
sheet of glass. The greater the number of encoder pulses per revolution, the higher the
resolution of the encoder.
Sometimes the encoder data gives the encoder resolution (e.g. 12-bit resolution),
rather than the number of tallies. The encoder pulses per revolution are calculated
as follows:
Encoder pulses per revolution = 2
96
U
Sine track
Sine pick-off
Cosine pick-off U
Cosine track
resolution
Excitation: 2 to 10 kHz
Rotary
transformer
Connection of the SINAMICS S120 to the Technology CPU
Product Information, 09/2011, A5E00480378-04