Filter
Top Products
8 - 6
MELSEC-
A
8 ZERO POINT RETURN CONTROL
8.2.3 Zero point return method (1): Near-point dog method
The following shows an operation outline of the "near-point dog method" zero point
return method.
Operation chart
1)
The machine starts a machine zero point return.
(The machine starts acceleration specified in "
Pr.53
Zero point return acceleration time selection" in the
direction set in "
Pr.46
Zero point return direction", and moves at " Pr.48 Zero point return speed".)
2) The machine detects near-point dog ON and starts deceleration.
3)
The machine decelerates to "
Pr.49 Creep speed" and then moves at the creep speed.
4)
At the first zero point signal after near-point dog OFF, pulse output from the D75P2 stops and "deviation
counter clear output" is output to the drive unit.
5)
After the completion of "deviation counter clear output", the zero point return complete flag (RX(n+2)0,
RX(n+5)0) turns from OFF
ON and the zero point return request flag (RX(n+1)F, RX(n+4)F) turns from
ON
OFF.
Md.30 Machine feed value
Current feed value
[RWrn+ 0 to 1, RWrn+8 to 9]
Md.44 Movement amount
after near-point dog ON
Axis operation status
[RWrn+7, RWrn+15]
Md.44 Movement amount after near-point dog ON
t
Machine zero point return start
(Positioning start signal)
ON
OFF
Pr. 48 Zero point return speed
Deceleration at the near-point dog ON
Pr. 49 Creep speed
ON
OFF
OFF
ON
Standing by
In zero point return
Inconsistent
0
Value the machine moved is stored
Zero point address
V
Zero point signal
Value of *1.
Deviation counter clear output
Near-point dog
ON
One servomotor rotation
*
1
1) 2) 3) 4) 5)
Standing by
Inconsistent
Adjust so the near-point dog OFF position is
as close as possible to the center of the zero
point signal HIGH level.
If the near-point dog OFF position overlaps
with the zero point signal, the zero point return
stop position may deviate by one servomotor
rotation.
Zero point return request flag
[RX(n+1)F, RX(n+4)F]
Zero point return complete flag
[RX(n+2)0, RX(n+5)0]
OFF
Fig. 8.2 Near-point dog method machine zero point return