Technical Manual PD4-E-M (EtherCAT)
5 General concepts
5.3.3 Gear ratio
The gear ratio is calculated from motor revolutions (6091
:1 (Motor Revolutions)) per axis rotation
(6091
:2 (Shaft Revolutions)) as follows:
Motor revolution (6091h:1)
Gear ratio =
Shaft revolution (6091h:2)
5.3.4 Feed constant
The feed constant is calculated from the feed (6092
h
:1 (Feed) per revolution of the output shaft
(6092
:2 (Shaft Revolutions) as follows:
Feed Constant =
Feed (6092
h
:01)
Shaft Revolutions (6092
h
:02)
The feed constant is useful for specifying the lead screw pitch for a linear axis and is used if the unit is
based on length dimensions or if it is dimensionless.
5.3.5 Calculation formulas for user units
Position unit
contains:
•
Bits 16 to 23: The position unit (see chapter Units)
•
Bits 24 to 31: The exponent of a power of ten (see chapter Units)
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Factor
Unit
reserved (00h)
reserved (00h)
Example
If 60A8
h
is written with the value "FF410000
h
" (bits 16-23=41
h
and bits 24-31=FF
h
), the unit
is set to tenths of degree (factory setting).
With a relative target position (607A
) of 3600, the motor moves exactly one mechanical
revolution, if Gear ratio is 1:1. The Feed constant plays no role in this case.
Example
If 60A8
h
is written with the value "FD010000
h
" (bits 16-23=01
h
and bits 24-31=FD
h
(=-3)), the
unit is set to millimeter.
With a relative target position (607A
) of 1, the motor moves exactly one mechanical
revolution, if Feed constant and Gear ratio are 1:1.
If the Feed constant is set according to the lead screw pitch of a linear axis, the motor turns
far enough that a feed of 1 mm is achieved.
Version: 1.0.1 / FIR-v1748
43
