Configuring the sensor – Overview of functions
Leuze electronic
OGS 600
42
TNT
35/7-2
4
V
7.6
"Minimum contrast" filter
The filter for the minimum contrast queries whether the brightness of the background and
the brightness of the trace have a minimum difference.
This minimum difference can be taught based on a reference trace, or the value can be set
manually.
Figure 7.6:
Application of the "Minimum contrast" filter using a dark trace as an example
7.6.1
Teaching the minimum contrast
The value of the
TraceContrastTol
parameter (UART index 105
d
and CAN index 2010
h
[6
h
])
is used for calculating a minimum threshold for the contrast using the contrast value
measured during the teach. The value appears as a percentage [%] in the index.
Calculation in the sensor:
Contrast =
│
Amplitude_environment - Amplitude_trace
│
TraceContrastMin
= Contrast - ( Contrast *
TraceContrastTol
/100 )
0
3000
y
x
A
B
C
D
x
Edge position
y
Reception signal amplitude
A
Left edge of guide trace
B
Right edge of guide trace
C
Trace width
D
Amplitude of background
E
Amplitude of guide trace
F
Contrast
G
Warning threshold for minimum contrast
H
Minimum contrast (
TraceContrastMin)
J
Verification of minimum contrast.
The second, right trace is not output because the minimum contrast is not fulfilled.
G
E
F
H
J
