Front Panel Operation
2-87
External Triggering and Trigger Link
As previously mentioned, the trigger pulses for the asynchro-
nous Trigger Link are identical to the trigger pulses used for
External Triggering. The only thing that prevents them from
being used together in a test system is connection incompat-
ibility. Trigger Link uses an 8-pin micro-DIN connector
while External Triggering uses two BNC connectors.
This connection problem can be solved by using the Model
8502 Trigger Link Adapter. The adapter has two 8-pin micro-
DIN connectors and six BNC connectors. The micro-DIN
connectors mate directly to the Trigger Link connector on
the Model 6517A using a trigger link cable. The BNC con-
nectors mate directly to the External Triggering BNC con-
nectors on other instruments using standard male BNC to
BNC cables.
Figure 2-67 shows how a Keithley Model 706 Scanner can be
connected to the Trigger Link of the Model 6517A using the
adapter. With this adapter, a Model 706 could be substituted
Idle
Bypass
B
Wait for
Trigger Link
Trigger
Scan
Channel
C
Output
Trigger
Trigger
D
No
Yes
7001or 7002
Make
Measurement
6517A
Press STEP to start scan
Arm
A
Wait for
Trigger Link
Trigger
E
Output
Trigger
Trigger
F
No
Yes
Scanned
10
Channels
?
Made
10
Measurements
?
Figure 2-66
Operation model for asynchronous trigger link example #1
for the Model 7001/7002 in the previous example (Asyn-
chronous Trigger Link example #1). With the Model 706 set
for External Triggering, the test would start when the single
scan mode is selected and initiated.
Asynchronous Trigger Link example #2
In this example, the test system (Figure 2-68) includes a
Model 6517A to measure each DUT at two different current
levels that are provided by a Model 220 current source. With
the source set to the first current level, the ten channels are
scanned and measured. The source is then set to the second
current level and the ten channels are again scanned and
measured.
Since this example uses an instrument that does not have
Trigger Link (Model 220), the Model 8502 Trigger Link
Adapter is required. Connections are shown in Figure 2-69.
For this example, the Model 220 is programmed for External
Triggering and is set to source the first current level. The
Models 6517A and 7001/7002 are configured as follows.
