
1.AXIS CONTROL B-63323EN-1/03
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1.14 TURNING MODE AND COMPENSATION CLAMP OF DUAL
POSITION FEEDBACK
Overview
For axes controlled by the dual position feedback function, turning
mode and compensation clamp are newly available. For details on the
dual position feedback function, refer to the "FANUC AC SERVO
MOTOR α Series Parameter Manual" (B-65150E).
ETurning mode
When the dual position feedback turning mode select signal is input to
the CNC, it selects turning mode. In turning mode, the feedback in the
closed loop for the axis set by bit 0 (STH) of parameter No. 1930 is
ignored. When a move command is issued in turning mode, only
semi-closed loop control is provided.
This function is used to switch the control method depending on the
situation; for example, a certain axis may be placed under position
control by the servo motor or may be controlled as a spindle by the
spindle motor.
In turning mode, feedback in the closed loop is ignored, which allows
all the coordinates (machine coordinates, workpiece coordinates, and
local coordinates) to be shifted by the amount of movement performed
in turning mode. Therefore, once turning mode has terminated,
reference position return is required to match the coordinates. If an
attempt is made to perform automatic operation without first
performing reference position return, alarm PS0181 is issued.
NOTE
For an axis for which turning mode is to be used, an
absolute-position detector cannot be used.
ECompensation clamp
When the dual position feedback compensation clamp signal is input to
the CNC, it stops dual position feedback compensation. As the
compensation stops, the feedback in the closed loop is halted, and
operation is performed in the semi-closed loop. Whenever the axis
subjected to dual position feedback is to be clamped mechanically,
compensation clamp must be applied. This function works on the axis
for which bit 2 (HYB) of parameter No. 1817 is set to 1.