Incremental signals

HTL square-wave signals

HEIDENHAIN encoders with  HTL interface incorporate electronics that digitize sinusoidal scanning signals with

or without interpolation.

The incremental signals are transmitted as the square-wave pulse trains Ua1 and Ua2, phase-shifted by 90° elec.The reference mark signal consists of one or more reference pulses Ua0, which are gated with the incremental signals. In addition, the integrated electronics produce their inverse signals Ua1^(Inverted), Ua2^(Inverted),  and Ua0^(Inverted)for noiseproof transmission (does not apply to HTLs).

 The illustrated sequence of output signals—with Ua2 lagging Ua1—applies to the direction of motion shown in the

dimension drawing.

 The fault-detection signal UaS^(Inverted), indicates  fault conditions such as failure of the light source. It can be used for such purposes as machine shut-off during automated  production.

 The distance between two successive  edges of the incremental signals Ua1 and Ua2 through 1-fold, 2-fold or 4-fold

evaluation is one measuring step.

 The subsequent electronics must be designed to detect each edge of the  square-wave pulse. The minimum edge separation a stated in the specifications refers to a measurement at the output of the given differential input circuit. To prevent counting errors, the subsequent electronics should be designed so that

they can process as little as 90 % of the edge separation a.

 The maximum permissible shaft speed or traversing velocity must never be exceeded.

 The permissible cable length for incremental encoders with HTL signals depends on the output frequency, the effective supply voltage, and the operating temperature of the encoder.

 The current requirement of encoders with HTL output signals depends on the output frequency and the cable length to the subsequent electronics.