Mitsubishi FX2N-10GM, Hardware / Programming Manual

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FX Series Positioning Controllers Program Examples 9
9-3
9.2.2 System of units
There are three types of systems of units, the mechanical system, the motor system and the
composite system, which offer the following characteristics.
Mechanical system [0]:
When you select this system, you have to set the unit of parameters related to the movement
quantity and the speed as well as the unit of the movement quantity and the operation speed in
the mechanical quantity (mm/min, cm/min). In addition, you have to set the pulse rate and the
feed rate.
Motor system[1]:
When you select this system, you have to set the unit of parameters related to the movement
quantity and the speed as well as the unit of the movement quantity and the operation speed in
the pulse quantity (pls, Hz). You do not have to set the pulse rate and the feed rate.
Composite system [2]:
When you select this system, you have to set the unit of parameters related to the movement
quantity and the unit of the movement quantity in the mechanical quantity (mm), and the unit of
parameters related to the speed and the unit of the operation speed in the pulse quantity (Hz).
In addition, you have to set the pulse rate and the feed rate.
In program examples shown in this section, the composite system of units [2] is adopted.
When using the composite or mechanical system of units, set the pulse rate and the feed rate
as described below.
9.2.3 Pulse rate and feed rate
Obtain the pulse rate and the feed rate as follows.
1) The pulse rate indicates the pulse quantity required for one rotation of the servo motor, and
can be obtained using the equation
d
Pulse rate (parameter No. 1) A = P
f
×
..............................................................
d
When the values (CMX = 256, CDV = 125) obtained in Paragraph 9.2.1 are substituted in
the equation
d
and the pulse rate is obtained,
Pulse rate (parameter No. 1) A = 8192 [pls/rev]
×
= 4000 [pls/rev]
2) The feed rate indicates the workpiece movement quantity by one rotation of the servo motor
shaft. In the system shown in Paragraph 9.1, the feed rate can be obtained using the follow-
ing equation.
Feed rate (parameter No. 2) B
= [Speed reducer ratio]
×
P
B
[Ball screw pitch]
×
.........
e
Actually, it can be obtained as follows.
Feed rate (parameter No. 2) B =
×
5 [mm]
×
= 5 [mm/rev]
= 5000 [
µ
m/rev]
1
CMX
CDV
1
256
125
1
Number of rotations
1
1 1
1[rev]