Output Signals - HEIDENHAIN PWM 8 Operating Instructions Manual

12.1.3 Output Signals

TTL
TTL square-wave signals
Encoders that output TTL square-wave signals feature electronics that digitize the sinusoidal scanning
signals without interpolation.
Two TTL square-wave signals Ua1 and Ua2 that are phase-shifted by 90° are output together with the
reference pulse Ua0 gated with the incremental signals Ua1 and Ua2. Encoders with distance-coded
reference marks output several Ua0 reference pulses.
The measuring step results from the distance between two edges of the signals Ua1 and Ua2.
To each square-wave signal the integral electronics in addition outputs the corresponding inverted signal.
Incremental signals
Edge separation
The scanning frequency depends on the encoder model.
Reference mark signal
Pulse width
Delay time
Fault detection signal
TTL square-wave signal trains Ua1, Ua2 and their inverted
Ua1
signal trains and
Ua2 lags Ua1 with ccw rotation (view on shaft or on encoder
flange) or when the scanning unit moves away from the ID plate -
of the linear encoder.
a ≥ 0.4 µs at 400 kHz scanning frequency
a ≥ 0.45 µs at 300 kHz scanning frequency
a ≥ 0.8 µs at 160 kHz scanning frequency
a ≥ 1.3 µs at 100 kHz scanning frequency
1 square-wave pulse Ua0 and its inverted pulse
90° elec.
It d l ≤ 50 ns
UaS
1 square-wave pulse
(single-ended signal: max. cable length 50m)
UaS
= LOW: fault detected
UaS
= HIGH: device operates properly
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Ua2
.
Ua0