| HEIDENHAIN encoders with » 1-VPP interface provide voltage signals that can be highly interpolated. The sinusoidal incremental signals A and B are phase-shifted by 90° elec. and have an amplitude of typically 1 Vpp. The illustrated sequence of output signals—with B lagging A—applies for the direction of motion shown in the dimension drawing. The reference mark signal R has a usable component G of approx. 0.5 V. Next to the reference mark, the output signal can be reduced by up to 1.7 V to a quiescent value H. This must not cause the subsequent electronics to overdrive. Even at the lowered signal level, signal peaks with the amplitude G can also appear. The data on signal amplitude apply when the power supply given in the specifications is connected to the encoder. They refer to a differential measurement at the 120 ohm terminating resistor between the associated outputs. The signal amplitude decreases with increasing frequency. The cutoff frequency indicates the scanning frequency at which a certain percentage of the original signal amplitude is maintained: • -3 dB ^ 70 % of the signal amplitude • -6 dB = 50 % of the signal amplitude The data in the signal description apply to motions at up to 20% of the -3 dB cutoff frequency. Interpolation/resolution/measuring step The output signals of the 1 Vpp interface are usually interpolated in the subsequent electronics in order to attain sufficiently high resolutions. For velocity control, interpolation factors are commonly over 1000 in order to receive usable velocity information even at low speeds. Measuring steps for position measurement are recommended in the specifications. For special applications, other resolutions are also possible. Short circuit stability A temporary short circuit of one signal output to 0 V or Up (except encoders with Upmin = 3.6 V) does not cause encoder failure, but it is not a permissible operating condition. |