Mitsubishi A1SD75M1, User Manual

Page: 351 / 746

8 - 17
MELSEC-A
8 ZERO POINT RETURN CONTROL
Restrictions
•
The system where the machine can move by the movement amount of more
than one servomotor revolution is required.
•
The system should satisfy the condition that the upper/lower limit stroke limit
signal does not turn OFF when the servomotor rotates one turn in the opposite
direction following a stop made when the machine has moved the movement
amount set to " Pr.52 Setting for the movement amount after near-point dog
ON" after the near-point dog has turned ON.
Precautions during operation
(1) If " Pr.52 Setting for the movement amount after near-point dog ON" is less
than the distance of deceleration from " Pr.48 Zero point return speed" to
" Pr.49 Creep speed", an error "count method movement amount fault" (error
code: 206) occurs, disabling a start.
The machine decelerates to a stop if an error occurs due to a speed change
made midway during operation.
(2) The operation performed when a machine zero point return is stared while the
near-point dog is ON is the same as in the "count method 1)".
(3) Turn OFF the near-point dog sufficiently away from the zero point position.
If the near-point dog is turned OFF during a machine zero point return, there is
no harm in operation. For the following reason, however, it is recommended to
turn OFF the near-point dog sufficiently away from the zero point position.
Reason: If a machine zero point return is made continuously after the near-
point dog is turned OFF at completion of a machine zero point return,
the machine operates at the zero point return speed until it reaches
the hardware stroke limit (upper/lower limit).
(4) When the zero point is not passed from a machine zero point return start until
the machine moves the movement amount set to " Pr.52 Setting for the
movement amount after near-point dog ON", do not touch the servomotor and
positioning system until the machine zero point return is completed.
(When the servomotor rotates one turn in the opposite direction, the AD75
waits until the in-position signal and zero speed signal of the servo amplifier
turn ON. If the servomotor or positioning system is touched in the status where
the stop position has not yet been reached, the in-position signal and zero
speed signal may turn ON due to the motor side load, rotating the servomotor
suddenly in the opposite direction and positioning the machine to the zero
point.)
(5) If the restart command is turned ON after the machine zero point return is
stopped by the stop signal, an error "zero point return restart not possible"
(error code: 209) occurs.
REMARK
•
In the "count method 3)" zero point return method, a machine zero point return
can be made while the near-point dog is ON.
•
In the "count method 3)" zero point return method, a continuous start can be
made after completion of a machine zero point return.