Mitsubishi A1SD75P1-S3, User Manual

Page: 430 / 622

12 - 17
MELSEC-A
12 CONTROL AUXILIARY FUNCTIONS
(3) Precautions during control
It is recommended that the "movement amount per pulse (A)" be set to a value
close to "1" for the following reasons.
“1” set in the “movement amount per pulse” indicates the minimum value of
“ Pr.1 Unit setting.” (In case of [mm] unit: 0.1 [
µ
m])
"Movement amount per pulse" = "1" means the minimum value of " Pr.1 Unit
setting". (0.1 [(m] when the unit setting is [mm])
(a) If the setting of the movement amount per pulse is less than 1, the
command frequency increases, and the actual speed may exceed the speed
limit value ( Pr.7 Speed limit value, Pr.32 JOG speed limit value),
causing the servomotor speed to be overspeed.
(b) If the setting of the movement amount per pulse is less than 1, the
mechanical system may vibrate.
(c) Set the movement amount per pulse that will make the pulse output
frequency to the drive unit not more than 400kpps when the differential
driver is connected, or not more than 200kpps when the open collector is
connected.
If the setting of the movement amount per pulse is a value that will make the
pulse output frequency to the drive unit more than 400kpps (when the
differential driver is connected) or more than 200kpps (when the open
collector is connected), the AD75 may operate improperly.
(d) Depending on the servomotor resolution (No. of PLG pulses), the speed
may not reach the rated speed, even when the pulses are output from the
AD75 at the max. pulse output frequency. In this case, a drive unit electronic
gear function, etc., is jointly used.
(Example) No. of pulses per servomotor rotation = 16384 pulses
Rated speed = 2000r/min
AD75 differential driver = 400kpps
In this case, the speed is calculated by the following equation.
400000
16384
×
60 = 1465 (r/min) < 2000 (r/min)
REMARK
In the AD75, the general term for the functions in items (a) to (c) above is defined as
the "electronic gear function". Refer to the User's Manual for the servomotor for the
definition of the "electronic gear" on the servomotor side.
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