
14.ABSOLUTE-POSITION DETECTION OPERATION B-63324EN-1/03
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14 ABSOLUTE-POSITION DETECTION
On an axis equipped with an absolute pulse coder, the machine position
is monitored even when the CNC power is turned off, so return to the
reference position is unnecessary when the power is turned on again.
An absolute pulse coder consists of an ordinary incremental pulse
coder equipped with an absolute counter. Based on the counter value,
an absolute position can be detected.
The absolute pulse coder uses the backup battery so that the pulse coder
monitors the machine position by the counter if the CNC is turned off.
If an absolute pulse coder is installed on an axis, the current position on
that axis is read from the absolute counter when the CNC is turned on,
and the machine coordinate system and workpiece coordinate system
are automatically set based on the read value. Automatic operation can
thus start immediately.
The requirements for reference position return after power-on
operation, described in this manual, do not apply to axes equipped with
an absolute pulse coder.
Explanation
- Initial Setting at Power-On
(1) The machine coordinate system and a workpiece coordinate
system are set automatically.
The G54 coordinate system is selected as the workpiece
coordinate system.
(2) The offsets from the workpiece reference point which are
specified with G92 and G52 are cleared.
(3) Relative coordinates (RELATIVE) for indicating a position are
set with the DSE bit, bit 1, of parameter No. 2202.
(4) The other initial settings at power-on are the same as when the
absolute position detection function is not provided.
- Manual Reference Position Return
In the following cases, be sure to manually return to the reference
position to associate the reference position with the counter value of
the absolute pulse coder:
(a) First field adjustment (after the reference position is defined)
(b) When the reference position is changed
(c) When the absolute pulse coder is replaced.
(d) When alarm OT32 occurs
(e) When the file memory is replaced
(f) When the file memory is cleared
Manually return to the reference position as follows:
(1) Set APZ, bit 4 of parameter No. 1815, to 0.
(2) Turn the power off then on again. Alarm OT32 is then displayed.