Yaskawa MP920 User's Manual Design - Manual (Page 460)

10.3 Using an Absolute Encoder
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10.3 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.
10.3.1 Finite Length Mode Axis
„ 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
determined without returning to the zero point when the system is started up. Once the sys-
tem is started, the encoder functions just like an incremental encoder.
Unfortunately, the maximum number of rotations from the encoder zero point is ±99999
rotations at which point it is reset to 0. When system power is turned ON therefore, the
MP920 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.
Therefore be sure to note the following precautions when using an absolute encoder as a
Finite Length Mode Axis.
• Be sure to initialize the encoder prior to setting the zero point.
• Use an absolute encoder only within the range of
±99999 rotations
Note: The actual machine operating range may vary depending on parame-
ters like the gear ratio.
• Do not change the Zero Point Position Offset (OL††06) while operating in Finite Length
Mode.
Otherwise this may cause machine damage or an accident.
CAUTION
0
(-99999 rotations) (+99999 rotations)
Reverse limit
Zero
point
Reverse
direction Forward
direction
Forward limit