REXROTH IndraDyn A Series, Project Planning Manual

Page: 174 / 220

9-18
Application Notes Rexroth IndraDyn A
Accuracy/Repeatability
There are two types of accuracy for rotary encoders: "absolute accuracy"
and "relative accuracy".
The absolute accuracy of rotary encoders is determined primarily by the
quality and precision of the encoder construction as well as by the
mechanical attachment to the motor.
The following values apply to IndraDyn A motors:
Encoder option
acc. to type
code
Technical data
Absolute
accuracy
C0
Incremental encoder, sinus/cosine signal
1Vpp with 2048 lines/rev
± 0.0056°
(± 20" )
M0
Multi-turn incremental encoder with I²C
interface.
Incremental encoder, sinus/cosine signal
1Vpp with 512 lines/rev
± 0.0167°
(± 60" )
M2
Multi-turn incremental encoder with
EnDat2.1 interface. Incremental encoder
sinus/cosine signal 1Vpp with 2048 lines/rev
± 0.0056°
(± 20" )
S0
Single-turn incremental encoder with I²C
interface. Incremental encoder
sinus/cosine signal 1Vpp with 512 lines/rev
± 0.0167°
(± 60" )
S2
Single-turn incremental encoder with
EnDat2.1 interface. Incremental encoder
sinus/cosine signal 1Vpp with 2048 lines/rev
± 0.0056°
(± 20" )
Fig. 9-19: Absolute accuracy of encoder
The relative accuracy of encoder systems is also referred to as
"repeatability". It is determined primarily by the interpolation variances
during further processing of the measured signals in the internal and
external interpolation - and digitization electronics.
For IndraDyn A motors, the following guidelines apply for operation with
Rexroth drive controllers (as of the publishing date of this documentation):
Encoder option
acc. to type
code
Technical data
Relative
accuracy
C0
Incremental encoder, sinus/cosine signal
1Vpp with 2048 strokes
± 0.01'
M0
Multi-turn incremental encoder with I²C
interface.
Incremental encoder, sinus/cosine signal
1Vpp with 512 lines/rev
± 0.005'
M2
Multi-turn incremental encoder with
EnDat2.1 interface. Incremental encoder
sinus/cosine signal 1Vpp with 2048 lines/rev
± 0.005'
S0
Single-turn incremental encoder with I²C
interface. Incremental encoder
sinus/cosine signal 1Vpp with 512 lines/rev
± 0.001'
S2
Single-turn incremental encoder with
EnDat2.1 interface. Incremental encoder
sinus/cosine signal 1Vpp with 2048 lines/rev
± 0.001'
Fig. 9-20: Relative encoder precision
Continuous development of the hardware and firmware for drive
controllers may result in variances from the above values. Therefore,
Absolute Accuracy
Relative Accuracy
“Repeatability”