Copyright © 2012 - 2017 ABI Electronics Ltd
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8.6 Comparison tolerances
These settings change the way that SENTRY scans devices and makes comparisons.
The SENTRY compares
PinPrints
between devices, and attempts to produce a result for each pin and for the overall device.
You can set the tolerances and limits for this decision using the
Comparison Options
. Click on
Comparison
tab in the
Administration
section. Each saved device has its own tolerance settings, and the device you are editing is shown at the top
of the
Comparison
tab. It is possible to view the comparison options when no device is selected; in this case the user default
values are shown.
The comparison tolerances work in three stages – point by point comparison, pin by pin comparison, and overall device
comparison. The result of the comparison for each individual pin can be
SUCCESS
,
SUSPECT
or
FAIL
. The SENTRY
compares the
PinPrint
point by point, using the specified Comparison Point Tolerances, for a genuine and suspect device and
produces a percentage match figure for the pin. Once the SENTRY has evaluated the comparison result for each pin, it then
derives an overall result for the device by checking the number of FAIL and SUSPECT pins. Note that both FAIL and SUSPECT
pins can cause both FAIL and SUSPECT results, depending on how many there are.
a) Comparison point tolerance
These values are used to generate a mask around the recorded data inside which any points are deemed to be valid. Any
points outside this mask are deemed to be invalid. The software uses the number of points inside and outside the mask when
calculating the pin status.
Horizontal tolerance
– The percentage of the total range that the measurement needs to be within in the horizontal direction for
the data to be deemed valid.
Vertical
– The percentage of the total range that the measurement needs to be within in the vertical direction for the data to be
deemed valid.
It is possible to restore the default settings for these by clicking the
Restore Default
button, which sets all the values to the
saved user defaults.
b) Pin comparison tolerance
FAIL: If the percentage match figure for the pin is less than or equal to the specified FAIL tolerance, the pin result will be FAIL.
SUSPECT: IF the pin result is not FAIL, but the percentage match figure for the pin is less than or equal to the specified
SUSPECT tolerance, the pin result will be SUSPECT.
SUCCESS: If neither of the above applies, the pin result will be SUCCESS.
It is possible to restore the default settings for these by clicking the
Restore Default
button, which sets all the values to the
saved user default values.
c) Overall result tolerance
FAIL: If the percentage of pins with a FAIL result is greater than the specified
FAIL when failed pins >
setting, or if the
percentage of pins with a SUSPECT result is greater than the specified
FAIL when suspect pins >
setting, the overall device
result will be FAIL
SUSPECT: If the overall result is not FAIL, but the percentage of pins with a FAIL result is greater than the specified
SUSPECT
when failed pins >
setting, or if the percentage of pins with a SUSPECT result is greater than the specified
SUSPECT when
suspect pins >
setting, the overall device result will be SUSPECT.
SUCCESS: If neither of the above applies, the overall device result is SUCCESS.
It is possible to restore the default settings for these by clicking the
Restore Default
button, which sets all the values to the
saved user default values.
