HEIDENHAIN PWM 20 - Manual (Page 211)

212 HEIDENHAIN ATS Software User's Manual
7.2.2 Incremental signals 1 Vpp
The sinusoidal incremental signals A and B are phase-shifted by 90° elec. and have a signal
amplitude of 1 Vpp typ. The usable component of the reference mark signals R is approxi-
mately 0.5 V. The values for the signal amplitudes apply for Up = 5 V
 5 % at the encoder (see
Encoder specifications) and refer to a differential measurement at a 120
 terminating resistor
between the associated outputs. The signal amplitude changes with increasing scanning
frequency.
The linear encoders with single reference marks have a reference mark every 50 mm of the
glass scale, one or several of which can be activated by means of a selector magnet. The
quiescent level of the output signal is increased by approximately 1.5 V; the usable component
G of the reference mark signal to be evaluated is based on this level. Signal peaks with amplitude
G also appear in the quiescent level for the inactive reference marks every 50 mm.
Incremental signals Two nearly sinusoidal signals A and B
Reference mark
signal One or several signal peaks R
Connecting cables
Note
The stated tolerances are standard values!
The tolerances of measuring systems for high resolutions (e.g. angle encoders) and large
temperature ranges (e.g. motor encoders) are tighter!
The supply voltage of 5 V
5% at the encoder has to be ensured!
Signal amplitude M 0.6 to 1.2 Vpp
Typ. 1 Vpp
Recommended lower threshold sensitivity for
signal monitoring Min. 0.3 V
Recommended upper threshold sensitivity for
signal monitoring Max. 1.35 V
Asymmetry /2M 0.065 TV
15°
Signal ratio M
A
/ M
B
0.8 to 1.25
Phase angle /2 90°
10° el.
P - N =
ˆ
1 2
+
Usable component G 0.2 to 0.85 V
Quiescent value H Max. 1.7 V
Signal-to-noise ratio E, F Min. 40 mV, max. 680 mV
Zero crossovers K, L 180°
 90° el.
Shielded HEIDENHAIN cable PUR [4(2 x 0.14 mm
2
) + (4 x 0.5 mm
2
)]
Cable length Max. 150 m at 90 pF/m distributed
capacitance
Propagation time 6 ns/m