Keithley 2450 Reference Manual page 229

Section 3: Functions and features Model 2450 Interactive SourceMeter® Instrument Reference Manual
The tests are performed in ascending numeric order: Test 1 (VF), Test 2 (VR) and then Test 3 (IR).
Therefore, the value of VF is inspected against its limit first. The requirement for the value of the
limit's lower bound is that it not exceed some maximum value. To prevent false failures, you need to
set the lower limit value low enough that it will always be less than any value of V that may be
measured. The same is true for setting the lower limit value for IR.
If the VF test fails, the failure is recorded and testing continues with Test 2, the VR test. If the VF test
passes, then testing continues with the VR test.
If the VR test fails, and this is the first test failure, the failure is logged and testing continues with Test
3, the IR test. If the VR test passes, testing continues with the IR test, and so on until all three tests
are complete and all limit inspections have been performed.
If no tests fail, the overall "pass" digital bit pattern is output to the digital I/O, which causes the
component handler to place the diode in the Good Part bin. If any of the tests fail during the test
sequence, the "fail" bit pattern corresponding to the first failure is output, which causes the diode to
be placed in either an overall Bad Part bin, or a more specific Bad VF, Bad VR or Bad IR bin.
Figure 100: Diode grading trigger model with immediate binning blocks 1 to 8
3-84 2450-901-01 Rev. B/September 2013