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9 MAJOR POSITIONING CONTROL
POINTS
(1) In the continuous path control, a speed variation will not occur using the near-pass function when the
positioning data is switched (Refer to Section 12.3.3 "Near-pass function").
(2) The QD75MH holds the command speed set with the positioning data, and the latest value of the
speed set with the speed change request as the "
the "current speed" when "-1" is set in the command speed.
(Depending on the relation between the movement amount and the changed speed, the feedrate may
not reach the new speed value, but even then the current speed will be updated.)
(3) When the address for speed change is identified beforehand, generate and execute the positioning
data for speed change by the continuous path control to carry out the speed change without requesting
the speed change with a PLC program.
(3) Speed handling
(a) Continuous path control command speeds are set with each
positioning data.
The QD75MH then carries out the positioning at the speed designated
with each positioning data.
(b) The command speed can be set to "–1" in continuous path control.
The control will be carried out at the speed used in the previous
positioning data No. if the command speed is set to "–1".
(The "current speed" will be displayed in the command speed when
the positioning data is set with a peripheral device. The current speed
is the speed of the positioning control being executed currently.)
1)
The speed does not need to be set in each positioning data when
carrying out uniform speed control if "–1" is set beforehand in the
command speed.
2)
If the speed is changed in the previous positioning data when "–1"
is set in the command speed, the operation can be continued at
the new speed.
3)
An error "no command speed error (error code: 503)" occurs and
positioning cannot be started if "–1" is set in the command speed
of the first positioning data at start.
[Relation between the command speed and current speed]
V
3000
2000
1000
Da. 8 Command speed
Md. 27 Current speed
P1
P2
P3
P4
1000
3000
-1
-1
1000
3000
3000
3000
3000
The current speed is
changed even if the new
speed is not reached in P2.
Md.27
Current speed". It controls the operation at
9 - 11
P5
t
-1
MELSEC-Q
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