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11 SUB FUNCTIONS
V
Old speed
Cd.7
Pr.6
Fig. 11.2 Operation performed when axis stop signal ON or JOG start signal OFF occurs before new
speed value is reached
11 - 3
[2] Precautions during control
(1)
The time required to reach a new speed from an old speed at speed change is
" Cd. 8 ACC/DEC time at speed change".
For a deceleration stop made by axis stop signal ON or JOG start signal OFF
after the new speed is reached following a speed change request, the time
required to make a stop after reaching " Pr. 6 Bias speed at start" from the
operating speed is " Cd. 9 DEC/STOP time at speed change".
However, if the new speed ( Cd. 7 New speed value) is less than the old speed,
the time required to make a stop from axis stop signal ON or JOG start signal
OFF may exceed the preset deceleration stop time ( Cd. 9 ) when a deceleration
stop is made by axis stop signal ON or JOG start signal OFF right after the speed
change command (before " Cd. 7 New speed value" is reached). (See below.)
Note that the deceleration stop time is the "time required to make a stop from the
target speed", and not the "time required to make a stop from the current speed".
If axis stop signal ON or JOG start signal OFF occurs before the target speed is
reached, the time required to make an actual stop is determined by the "current
speed (speed at axis stop signal ON or JOG start signal OFF)" and "slope of
deceleration from the target speed to a stop (slope of deceleration found from the
target speed ( Cd. 7 ) and deceleration stop time ( Cd. 9 ))".
When it is necessary to make a stop in a short time before the target speed is
reached, make adjustment using the Cd. 9 value.
Speed change command
Axis stop signal ON or JOG start signal OFF
before target speed is reached
Target speed
Cd.8
Actual deceleration time
Axis stop signal ON or JOG start
signal OFF after target speed is
reached
Same slope
Preset deceleration stop time
Cd.9
MELSEC-Q
Cd.7
New speed value
ACC/DEC time at speed change
Cd.8
DEC/STOP time at speed change
Cd.9
Bias speed at start
Pr.6
t
11 - 3
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