Keithley 6487 Reference Manual

8-4 Limit Tests and Digital I/O Model 6487 Reference Manual
Figure 8-3
Operation model for limit test
klqb Display messages indicate which test or tests have failed, but they do not
indicate which limit (HI or LO) has failed. When using remote operation, you
can determine which limit failed by reading the measurement event register. See
Ref C for the FAIL? commands in Table 8-3 on page 8-18.
Relative (Rel), mX+b, m/X+b, and log can be used with limit testing. The tests
will be done on the result of the math operation (not the input values). These
math operations are covered in Section 5.
Application — A typical application for a 2-stage limit test is to sort a batch of DUT
according to tolerance. For example, you may want to sort diodes (all having the same
nominal value) into three groups, 1%, 5%, and >5%. The limits for Limit 1 would be the
5% tolerances and the limits for Limit 2 would be the 1% tolerances. If a diode passes both
tests, it belongs in the 1% group. If it passes Limit 1 but fails Limit 2, it belongs in the 5%
group. If it fails both tests, it belongs in the >5% group.
Pass
?
Start
Measure
DUT
Yes
Limit 1
Test
No
Display
“L1”
Limit 2
Test
Pass
?
Display
“L2”
Display
“OK”
Yes
No
End

Keithley 6487 Specifications

General

Type	Picoammeter/Voltage Source
Current Measurement Range	20 fA to 20 mA
Interfaces	GPIB, RS-232
Voltage Burden	< 200 µV
Input Impedance	>10^14 Ω
Power	100 V / 120 V / 220 V / 240 V
Basic Current Measurement Accuracy	0.4%