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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 [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.
In that case, make setting so that the movement amount per pulse is 1 or
more using the electronic gear function of the drive unit.
(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 D75P2 may operate improperly.
(d) "Current feed value (RWrn+0 to 1, RWrn+8 to 9)" and "
Md.30
Machine
feed value" are updated to reflect the number of pulses that are actually
output (whole number). If the movement amount per pulse is not set to 1,
the resulting value can differ from the target address by a fraction less than
one pulse.
(e) 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
D75P2 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
D75P2 differential driver = 400kpps
In this case, the speed is calculated by the following equation.
400000
60 = 1465 (r/min) < 2000 (r/min)
16384
REMARK
In the D75P2, 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.