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Differential output is a data transmission method by using dedicated IC output and based
on RS422-A specifications. The signal outputs as a differential 2 signal, so it has strong
anti-interference ability, suitable for long-distance and high-speed transmission. The
camera side uses a dedicated IC (called RS422 transceiver) to receive the signal sent by the
encoder.
Differential output
Figure 3-48
What is the difference between an incremental encoder and an absolute encoder?
After power failure, the incremental encoder does not record the angle that it has rotated
before the power failure. Absolute encoders can save the previously rotated angle after
power-off, and record up to 360°. Huaray line scan cameras only support incremental encoders.
What causes missing pulses of rotary encoder?
Possible reasons:
The encoder rotated too fast, exceeded the response frequency of the encoder or
subsequent device.
The wire is extended too long and the signal is attenuated.
Encoder hardware failure.
There is jitter or interference on site, such as jitter of mechanical transmission device and
electrical cable interference.
The encoder and the motor shaft are not fixed tightly, and there are eccentric feet.
How to know the quality of a rotary encoder?
Check whether the number of pulses is correct when connecting the camera.
Connect the oscilloscope to view the waveform.
Test whether the output is normal by using the multimeter.
When the encoder is NPN output: Test the positive pole of the power supply and the signal
output cable. When the transistor is turned on (ON), the output voltage is close to the
encoder supply voltage, and when the transistor is turned off (OFF), the output voltage is
close to 0 V.
When the encoder is PNP output: Test the negative pole of the power supply and the signal
output cable. When the transistor is turned on (ON), the output voltage is close to the
encoder supply voltage, and when the transistor is turned off (OFF), the output voltage is
close to 0 V.
What are rise time and fall time?
Rise time: The time for the output pulse to rise from 10% to 90%.
Fall time: The time for the output pulse to fall from 90% to 10%.
Rise time and fall time
Figure 3-49
