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Operation
optoNCDT 1402
Timing
6.5
The controller operates internally with real time cycles in a pipeline mode:
1. Exposure: Charging the image detector in the receiver (measurement).
2. Reading: Reading out of the imaging device and converting into digital data.
3. Computation: Measurement computation.
4. Controlling.
The output through the analog and digital interface starts with the beginning of every new cycle. The analog value and digital switch
outputs are updated immediately and the digital output starts with the start bit.
Each cycle takes 666 µs at a measuring rate of 1.5 kHz. The measured value N is available after each cycle with a constant lag of four
cycles in respect to the real time event. The delay between the input reaction and the signal output is therefore 2 up to 2.7 ms. The
processing of the cycles occurs sequentially in time and parallel in space (see Fig. 14, pipelining). This guarantees a true constant real
time data stream.
Cycle
1.
2.
3.
4.
5.
6.
Time max. 5 s
666 µs
1322 µs
1998 µs
2664 µs
3330 µs
3996 µs
Initialisation
including the
output of the
info string
Exposure N
Reading N
Computation N Controlling N
Output N
Exposure N+1 Reading N+1
Computation N+1 Controlling N+1
Output N+1
Exposure N+2 Reading N+2
Computation N+2 Controlling N+2
...
Exposure N+3
Reading N+3
Computation N+3 ...
First exposure after power up of the sensor
Exposure N+4
Reading N+4
...
...
...
Sensor timing at a measurement rate of 1.5 kHz
Fig. 14:
i
The sensor needs time until measuring values are available according to the set averaging number N.
