8-8
Limit Tests and Digital I/O
Model 6487 Reference Manual
Digital output patterns
The Model 6487 uses digital output bit patterns to communicate test results to the compo-
nent handler. For each limit test, unique fail patterns are used for the HI and LO limits. A
pass pattern is used to indicate that there were no errors. After a test is finished, the appro-
priate output pattern is sent to the component handler. The handler decodes the bit pattern
and places the DUT in the appropriate bin.
The Model 6487 can be used with either of the two basic types of handlers. When used
with a category pulse handler, the Model 6487 pulses one of the four handler lines. The
handler then places the DUT into the bin assigned to the pulsed line.
When used with a category register handler, the Model 6487 outputs a bit pattern to three
handler lines. After the Model 6487 sends the end-of-test (EOT) strobe pulse to the fourth
handler line, the handler places the DUT into the bin assigned to that bit pattern.
Component handler types
The Model 6487 can accommodate two different types of component handlers: category
pulse and category register.
Category pulse component handler
When using this type of handler, the Model 6487 pulses one of the four handler lines when
a pass or fail condition occurs. The handler then places the DUT in the bin assigned to that
pulsed line. When interfacing to this type of handler, a maximum of four component
handler bins are supported.
If the handler requires low-going pulses, then the four digital output lines of the
Model 6487 must be initially set to high. This initial HI, HI, HI, HI clear pattern on the
output lines represents a “no action” condition for the handler since it is waiting for one of
the lines to go low. A line goes low when the defined fail or pass pattern sets it low. For
example, if you want a particular test failure to pulse line #4 of the handler, the defined fail
pattern has to be HI, HI, HI, LO. When the failure occurs, line #4 will be pulled low and
the DUT will be placed in the bin assigned to that pulsed line.
If the handler requires a high-going pulse, the four digital output lines of the Model 6487
must initially be set low. The LO, LO, LO, LO clear pattern represents the “no action”
condition for the handler. When one of those lines are pulled high by a defined pass or fail
bit pattern (i.e., LO, LO, LO, HI), the DUT will be placed in the bit assigned to that pulsed
line.
