9-10
Extended Drive Functions
MPH-02, MPB-02, MPD-02
DOK-INDRV*-MP*-02VRS**-FK01-EN-P
Functional Description
Basics on Measuring Encoder, Resolution
The measuring encoder is mechanically connected to an axis or shaft and
detects its position data. These position data can be used as measured
values or command variable, but not as control variable.
Only rotary encoders can be used as measuring encoders. The possible
encoders are listed in parameter
P-0-0076, Encoder 3 (measuring
encoder)
.
The scaling of the position data generated with a measuring encoder is
rotary and axis- or shaft-related. Due to the infinite motion range of the
measuring encoder and the limited value range of the position data,
modulo scaling is set automatically.
See also "Mechanical Axis System and Measuring Systems: Scaling of
Physical Data" in chapter "Motor, Mechanical Axis System, Measuring
Systems"
The modulo range can only be selected as an integral multiple of an axis-
of shaft-side revolution and has an upper limit:
N
n
1;
11
2
2047
0765
0
P
n
utions)
haft revol
(axis or s
n
ulo range
mod
∈
−
=
≤
−
−
=
∗
=
n:
number of revolutions at axis or shaft
P-0-0765:
modulo factor measuring encoder
Fig. 9-4:
Modulo range at axis or shaft
The absolute precision is a feature of the encoder and is determined by
its construction and the quality of its components. The data for the
absolute precision are indicated by the manufacturer.
The resolution of the measuring system (division periods or cycles per
encoder revolution) is input in:
•
P-0-0327, Encoder resolution of measuring encoder
The analog encoder signals are converted to digital position data via A/D
converter. This increases the resolution of the position data available for
the axis compared to the resolution of the measuring system (see above)!
measuring encoder (rotary only):
P-0-0327
* 2
15
P-0-0327:
encoder resolution of measuring encoder
Fig. 9-5:
Maximum possible encoder resolution of measuring encoder per
encode revolution
The value range of the position data of the measuring encoder depends
on the modulo factor of the measuring encoder (P-0-0765):
N
n
1;
2
2047
0765
0
P
n
s)
(increment
2
n
range
value
11
20
∈
−
=
≤
−
−
=
∗
=
n:
number of revolutions at axis or shaft
P-0-0765:
modulo factor measuring encoder
Fig. 9-6:
Modulo value range at axis or shaft
Encoders to be Used
Scaling of Measuring Encoder
Position Data
Absolute Precision of Measuring
Encoder
Resolution (Division Periods)
Maximum Measuring Encoder
Resolution After Digitalization
Value Range of Position Data
Courtesy
of
CMA/Flodyne/Hydradyne
▪
Motion
Control
▪
Hydraulic
▪
Pneumatic
▪
Electrical
▪
Mechanical
▪
(800)
426-5480
▪
www.cmafh.com
