+
-
~
SECTION2
Operation
OPINLD•Cf'EHMm:M
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236-ILC-3
Interlock Cables
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Model
8006
Test
Fixture
-
OUT
It
©©
Source
Measure
Unit
#1
Figure
2-13.
Interlock
Connections
for
Multi
Unit
Test
System
Figure 2-13 provides a more detailed drawing showing
interlock connections. One interlock cable
is
provided
with the
Model8006
test fixture. Additional interlock ca-
bles can be ordered from Keithley (Model236-ILC-3).
In the drawing, the interlock cable from the test fixture is
connected to Interlock 1 of Source Measure
Unit
#1.
However, it could have just as well been connected to In-
terlock2. The interlock connectors
on
the Source Measure
Unit are wired identically (in parallel).
As shown
in
Figure
2-13,
The interlock of a single test fix-
ture
is
connected to one of the Source Measure
Units.
In-
terlock
is
then daisy-chained to the other
Source
Measure
Units in the test system. Connecting more than one test
fixture to the test system defeats the purpose
of
Interlock.
As long as one test fixture lid remains closed, the lid of an-
other test fixture can be opened without interrupting
power, thus exposing the user to potentially hazardous
voltage.
+
To another
Source
Measure Unit
Source
Measure
Unit
#2
2.4.2
Trigger Connections
The
Source Measure
Unit
can be programmed to output
one
or
more trigger pulses. Typically, a TRIGGER OUT
pulse
will
be
sent to a second Source
Measure
Unit
(TRIGGER IN) to start a programmed operation.
Trigger connections are shown
in
Figure
2-14.
In the
closed loop configuration, the Source Measure Units
keep triggering each
other
until the test sweep
is
com-
pleted (synchronous sweep). Typically, one unit
will
per-
form the sweep steps while the other
unit
sets bias levels.
In this configuration, a controller
is
not necessary. A con-
troller becomes necessary
when
more than one sweep
is
performed
by
a Source Measure Unit. Since a
Source
Measure
Unit
can only store the results of only one
sweep, the controller
is
needed to store the data so addi-
tional sweeps can be run.
The open loop configuration
is
typically used
when
a
computer
is
being used to control the test over the
IEEE-488
bus. In test configurations that use multiple
sweeps, a computer
is
required to store the sweep data
2-17
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