5.14 Setting Unit Systems
5.14.2 Setting the Speed Reference Unit
5-47
5
Basic Functions That Requir
e Setting befor
e Operation
5.14.2
Setting the Speed Reference Unit
Set the speed reference unit [Vel Unit] in
velocity user unit
(2702 hex).
Setting range: 1/128
≤
Numerator/Denominator
≤
8,388,608
(Alarm A.A20 will be detected if the setting exceeds the setting range.)
For a Rotary Servomotor with an encoder resolution of 24 bits (16,777,216), Pn20E (Electronic
Gear Ratio (Numerator)) is automatically set to 16 and Pn210 (Electronic Gear Ratio (Denomina-
tor)) is automatically set to 1. Therefore, the encoder resolution will be equivalent to 20 bits
(1,048,576). Consider this when you set the position reference unit in
position user unit
(2701
hex).
Index
Subin-
dex
Name
Data
Type
Access
PDO
Mappings
Value
Saving to
EEPROM
2702
hex
0
Number of entries
USINT
RO
No
2
No
1
Numerator
UDINT
RW
No
1 to 1,073,741,823
(default: 1)
Yes
2
Denominator
UDINT
RW
No
1 to 1,073,741,823
(default: 1)
Yes
Speed Reference Unit Setting Example (Electronic Gear Ratio Setting Example for a Ball
Screw)
•
Velocity User Unit (2702 Hex)
Converting one user-defined velocity reference unit [0.1 mm/s] into [inc/s]:
Therefore, the objects are set as follows:
Object 2702 hex: 01 (Numerator) = 1,048,576
Object 2702 hex: 02 (Denominator) = 60
Important
Example
1,048,576
60
1 [Vel unit]
=
=
16,777,216 [inc]
×
(1/16)
6 [mm]
×
0.1 [mm/s]
[inc/s]
