Automation Technology MCS 1280 Series, User Manual

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MCS Manual Rev. 1.4 35
Subpixel Limitations
The range values of the 3D sensors are limited to 16bit which result to possible values between 0
and 65535. Setting the subpixel value to 6 correspond to a factor of 2^6 = 64. If the laser line
appears at a sensor row higher than #1023 (with 6 subpixel) will result in a bit overflow. For
example: laser line at row #1500 -> 1500 x 2^6 = 96000.
Therefore, it can be necessary to use a lower subpixel value to avoid a bit overflow. The table
below shows the maximum subpixel value compared to the used number of rows and the laser
line appearance on the sensor ship without bit overflow.
The subpixel value in the factory configuration is always set to fit the complete Z-Range on the
sensor chip without overflows.
0 1 2 3 4 5 6
1023
✓ ✓ ✓ ✓ ✓ ✓ ✓
2047
✓ ✓ ✓ ✓ ✓ ✓ 
3072
✓ ✓ ✓ ✓ ✓  
Nevertheless, it is still possible to use a higher subpixel value even when the laser line appears on
a sensor row >#1023. In that case make sure that the defined AOI is smaller or even 1023/2047
rows and that the flag AbsOffsetPos (Camera Control -> Mode and Algorithm Control ->
AbsOffsetPos) is set to false. Then the offset position with respect to the start row of the AOI is
returned and thus the laser line can appear on sensor rows >#1023.
With the release of the C5-1280CS models some new features were implemented based on the
SFNC 2.3 standard as well as some AT specific features.
One new feature is the Mono8 mode in 3D line mode to reduce the amount of acquired data to
be able to increase the maximum profile frequency. This reduction leads to a specific set up which
is described in the table below.
0 1 2 3 4 5 6
3
✓ ✓ ✓ ✓ ✓ ✓ ✓
7
✓ ✓ ✓ ✓ ✓ ✓ 
15
✓ ✓ ✓ ✓ ✓  
31
✓ ✓ ✓ ✓   
63
✓ ✓ ✓    
127
✓ ✓     
255
✓      
Using number of rows with a higher subpixel accuracy then stated in the table above can result
in a bit overflow. That happen easy, when the pixel values go over the 8 Bit (2^8 - 1 = 255) range.
More details regarding the operation of the 1280 sensor can be found in a
separate application note.