Front Panel Operation
2-81
HOLD: When HOLD is selected, the arm source is sup-
pressed. As a result, operation does not pass into the scan lay-
er until HOLD is cancelled by selecting one of the other arm
source selections. Select HOLD from the SELECT ARM
SOURCE menu by placing the cursor on HOLD and press-
ing ENTER. The instrument returns to the SETUP arm layer
menu.
COUNT
This menu item defines the number of times operation re-
turns to the arm layer.
INFINITE: Use this selection to continuously return opera-
tion to the arm layer.
ENTER-ARM-COUNT: With this selection, the user deter-
mines the number of times operation returns to the arm layer.
You can program the Model 6517A to arm up to 99999
times.
CONTROL
Use this menu item to enable or disable the source bypass.
The source bypass is used to bypass the arm event on the first
pass through the arm layer.
SOURCE: With this selection, the source bypass is enabled.
The arm event will be bypassed on the first pass through the
arm layer. This allows operation to proceed into the scan lay-
er without having to wait for the programmed event.
ACCEPTOR: With this selection, the source bypass is dis-
abled.
Continuous Initiation
The INIT item of the ADVANCED TRIGGERING menu is
used to enable or disable continuous initiation.
ON: Use this option to enable continuous initiation. The in-
strument will not go into idle when all trigger model opera-
tions are done. Operation will instead start over from the top
of the advanced trigger model.
OFF: Use this option to disable continuous initiation. After
all advanced trigger model operations are done, the instru-
ment will go into idle.
Halting triggers
The HALT option of the ADVANCED TRIGGERING menu
is used to disarm the instrument and place it in the idle state.
You can press the TRIG key to resume front panel triggers.
Enabling (ON) continuous initiation will also take the instru-
ment out of idle.
2.15.4 External triggering
The Model 6517A has BNC connections on the rear panel
for external triggering (see Figure 2-58). The EXT TRIG IN
jack allows the Model 6517A to be triggered by other instru-
ments. The MTR COMP OUT jack allows the Model 6517A
to trigger other instruments.
External trigger
The EXT TRIG IN jack requires a falling-edge, TTL-com-
patible pulse with the specifications shown in Figure 2-59.
In general, external triggers can be used as events to control
measure operations. For the Model 6517A to respond to ex-
ternal triggers, the appropriate layers of the trigger model
must be configured for it. Paragraphs 2.15.2 and 2.15.3 ex-
plain how to program the three layers of the measurement.
Meter complete
The MTR COMP OUT jack provides a TTL-compatible out-
put pulse that can be used to trigger other instruments. The
specifications for this trigger pulse are shown in Figure 2-60.
EXT TRIG
IN
MTR COMP
OUT
Figure 2-58
External triggering connectors
Triggers on
Leading Edge
TTL High
(2V-5V)
TTL Low
(
≤
0.8V)
2µs
Minimum
Figure 2-59
External triggering and asynchronous trigger link input
pulse specifications
