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SM-Universal Encoder Plus User Guide
11
Issue Number: 6 www.controltechniques.com
Stegmann
Stegmann encoders typically have a 2.5Vdc offset. The sinref and cosref are a flat DC
level at 2.5Vdc and the cos and sin signals have a 1V peak to peak waveform biased at
2.5Vdc.
The result is a 1V peak to peak differential voltage as show in Figure 3-4.
Heidenhain
The Heidenhain Sin and Cos signals with respect to zero volts are offset at 2.5Vdc as
shown in Figure 3-5.
The feedback signals which are seen by the SM-Universal Encoder Plus are the
differential signals Sin - Sin\ and Cos - Cos\ as in Figure 3-5, these being 90° phase
shifted and at 1Vdc peak to peak.
Figure 3-5 Heidenhain SinCos encoder feedback signals
Encoders are available which have a 1V peak to peak voltage on sinref, sin, cos and
cosref. This results in a 2V peak to peak voltage seen at the Solutions Module terminals.
The drive will still function with this type of encoder, however reduced performance in
the form of speed and torque ripple at four times the line rate will result.
(line rate = no. of lines per revolution x revolutions per second.)
COS
2.5Vdc
SIN
0.25Vdc
SIN, COS signals
with respect to 0V
(offset at 2.5Vdc)
COS
SIN
0.5Vdc
0.5Vdc
Differential signals
received by
SM-Universal
Encoder Plus
0Vdc
COS ref SIN ref
0.25Vdc
It is recommended that encoders of this type are not used with Unidrive SP, and that the
encoder feedback signals should meet the above parameters (1V peak to peak).
NOTE