Yaskawa MP930 - Manual (Page 241)

Absolute Position Detection
7.3.1 Finite Length Mode Axis
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7.3 Using an Absolute Encoder
This section describes precautions regarding use as well as the procedure for setting the zero point
when using an absolute encoder.
7.3.1 Finite Length Mode Axis
J Overview
An absolute encoder stores the number of rotations from the encoder zero point in internal
memory backed up by battery. This way the zero point of the coordinate system can be deter-
mined without returning to the zero point when the system is started up. Once the system is
started, the encoder functions just like an incremental encoder.
Unfortunately, the maximum number of rotations from the encoder zero point is ¦99999 rota-
tions at which point it is reset to 0. When system power is turned ON therefore, the MP930
position may not be the same before and after power is turned ON.
A Finite Length Mode Axis has only limited movement that falls within a range of ¦99999
absolute encoder rotations.
Zero point
Reverse limit
Reverse
direction
Forward
direction
Forward limit
(+99999 rotations) (−99999 rotations)
Therefore be sure to note the following precautions when using an absolute encoder as a Finite
Length Mode Axis.
D Be sure to initialize the encoder prior to setting the zero point.
D Use an absolute encoder only within the range of ¦99999 rotations
Note: The actual machine operating range may vary depending on parameters like the
gear ratio.
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