R1: Reference point approach
15.10 Supplementary conditions
Basic Functions
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Function Manual, 09/2011, 6FC5397-0BP40-2BA0
15.10
Supplementary conditions
15.10.1
Large traverse range
Notes on uniqueness of encoder position
Linear absolute encoder
The absolute value of linear position encoders, e.g. Heidenhain LC181, is always unique for the scale lengths
available.
Rotary absolute encoder
The absolute value of rotary absolute encoders is only unique within the range of the specific maximum encoder
revolutions.
For example, the EQN 1325 rotary absolute encoder by Heidenhain supplies a unique absolute value in the
range of 0 to 4,096 encoder revolutions.
Depending on how the encoder is connected that will result in:
• Rotary axis with encoder on load: 4096 load revolutions
• Rotary axis with encoder on motor: 4096 motor revolutions
• Linear axis with encoder on motor: 4096 motor revolutions
Example
An EQN 1325 rotary absolute encoder is connected to the motor of a linear axis. For an effective leadscrew pitch
of 10 mm this will result in a unique absolute value within the travel range -20.48 to +20.48 m.
