
1.AXIS CONTROL B-63943EN-1/02
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1.4.3 Absolute Position Detection
Overview
An absolute position detector (absolute pulse coder) is an incremental
pulse coder with an absolute counter. It detects the absolute position
based on the value of the absolute counter. For an axis on which an
absolute position detector is mounted, no reference position return is
required at power-on because the machine position is always stored
with batteries if the power to the CNC is turned off.
When the machine position has been brought into correspondence
with the absolute position detector, the current position is read from
the absolute counter at CNC power on and the machine and workpiece
coordinate systems are automatically set using the value. In this case,
you can immediately start automatic operation.
Restrictions described in the USER’S MANUAL and others that
include those listed below are removed:
- "Reference position return is required after power-on."
- "The CNC can be used after reference position return is
performed after power-on."
Explanation
- Coordinate systems at power-on
(1) The machine and workpiece coordinate systems are
automatically set. When bit 3 (PPD) of parameter No. 3104 is
set to 1, the relative position display is preset.
(2) The amount of shift by coordinate system setting (G92 for the M
series or G50 for the T series) or local coordinate system setting
(G52) is cleared.
- Setting the zero point of an absolute position detector
In the following cases, set the zero point of an absolute position
detector (bring the counter value of the absolute position detector into
correspondence with the reference position):
- Primary adjustment is performed (after the reference position is
determined).
- The reference position is changed.
- An absolute position detector is replaced with another.
- A servo motor is replaced with another.
- Alarm (DS0300) is issued.
- The file memory is replaced with another.
- Parameter data is cleared.
To set the zero point of an absolute position detector, the following
two methods are available: One method using manual reference
position return and the other using MDI operation.