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XtrapulsPac - User Guide
Chapter 3 – Reference
3.2.2.7.7 - Absolute Multi-turn Position
With an absolute encoder feedback, the motor absolute position value over one revolution is available and the
servo motor can immediately be enabled after the amplifier power up. The servo drive behaviour at power up is
similar to a resolver sensor feedback. For a position application, an absolute multi-turn encoder allows avoiding
the homing sequence after power up. In this case, the absolute position value over the axis travel distance is
available at power up and the positioning can be immediately started. However, the axis must never leave the
encoder absolute position range.
Encoder Position Range
The absolute encoder gives a position value between 0 and a maximum position value (depending on the
encoder type).
For a Hiperface® encoder, the max. position value is given by:
(Number_of_revolutions x Number_of_periods x 4 x 8) - 1
Number_of_revolutions is the maximum revolution for that encoder.
Number_of_periods is the number of Sin-Cos periods per revolution
4 is the quadrature counter multiplier
8 is the interpolation factor.
Example 1:
Number_of_revolutions = 4096
Number_of_periods = 1024
Then, the maximum position value given by the encoder is 4096 x 1024 x 4 x 8 - 1 = 134 217 727 = 0x7FF FFFF
Once the encoder parameters set, this maximum position can be read with object 0x312D,1.
The current position of the encoder is given by object 0x312D,3
Note: these values are in encoder unit.
