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4.10.2 Channel ready
The CHANNEL READY output jack provides a TTL-
compatible output pulse that can be used to trigger
other instrumentation. The specifications for this trig-
ger pulse are shown in Figure 4-15.
Channel
Ready
TTL High
(3.4V Typical)
TTL Low
(0.25V Typical)
10µs
Minimum
Figure 4-15
Channel ready and asynchronous Trigger Link Output
pulse specifications
Typically, you would want the Model 7001 to output a
trigger after each channel closes and settles (settling
time includes the internally set relay settle time and the
user programmed DELAY period; see paragraph 4.7).
An output trigger will occur after each scanned chan-
nel as long as channel spacing is set to external. See
paragraph 4.8.1 for details on programming the chan-
nel layer.
The Model 7001 can also output a trigger while in the
scan and/or arm layers of operation. Figure 4-9 shows
where these triggers occur in the trigger model. An
output trigger will occur on each return path through
the scan layer if the scan layer Source Bypass is enabled
(Control = Source) and Scan Spacing is programmed
for External. An output trigger will occur on each re-
turn path through the arm layer if the arm layer Source
Bypass is enabled (Control = Source) and Arm Spacing
is programmed for External. See paragraph 4.8.2 and
4.8.3 for programming the scan and arm layer.
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4.10.3 External triggering example
In a typical test system, you may want to close a chan-
nel and then measure the DUT connected to that chan-
nel with a DMM such as the Keithley Model 196. Such
a test system is shown in Figure 4-16 which uses a
Model 7011 multiplexer card to switch 10 DUTs to the
DMM.
The external trigger connections for this test system are
shown in Figure 4-17. Channel Ready (output) of the
Model 7001 is connected to External Trigger Input of
the Model 196, and External Trigger (input) of the
Model 7001 is connected to Voltmeter Complete Out-
put of the Model 196.
For this test system, the Model 196 is configured for ex-
ternal triggering and the scan is configured as follows:
Scan List = 1!1-1!10,
Arm Layer:
Arm Spacing = Immediate*
Arm Count = 1*
Arm Trigger Control = Acceptor*
Scan Layer:
Scan Spacing = Immediate*
Number of Scans = 1
Scan Trigger Control = Acceptor*
Channel Layer:
Channel Spacing = External
Number of Channels = Use Scan list Length*
Channel Trigger Control = Source*
* Indicates that the setting is the RESET (and factory) default
condition.
Notice that Channel Trigger Control is set for Source.
With this selection, scan operation will initially bypass
the need for an external trigger to close the first chan-
nel. Since arm spacing and scan spacing are set for Im-
mediate, the scan will start immediately as soon as the
scanner is taken out of the idle state by pressing the
STEP key.
When the front panel STEP key is pressed, the scanner
will arm and close the first channel. After Channel 1!1
settles (channel ready), a trigger is sent from Channel
Front Panel Operation
4-49
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