Keithley 2001 Operator's Manual page 89

• With the External source selected, the instrument waits
for an input trigger via EXTERNAL TRIGGER on the
rear panel.
• With the Manual source selected, the instrument waits
until the front panel TRIG key is pressed.
• With the GPIB source selected, the instrument waits for
a bus trigger (GET or *TRG).
• With the Trigger Link source selected, the instrument
waits for an input trigger via TRIGGER LINK on the
rear panel.
• With the Timer source selected, operation immediately
proceeds into the measure layer on the initial pass
through the scan layer. Each additional scan does not
occur until the programmed timer interval elapses. The
timer can be set from 1msec to 999999.999sec.
• With the HOLD source selected, the instrument does
not respond to any of the event sources.
With the Immediate trigger source select-
ed, a "trigger ignored" message will be
displayed if an external trigger is sent to
the Model 2001 or a manual trigger (i.e.,
pressing TRIG key) occurs. The external
or manual trigger is not used (ignored).
After the programmed scan event is detected, the instrument
waits for the programmed Delay to time out. The scan layer
Delay can be set from 0 to 999999.999sec. Selecting
BENCH or GPIB RESET from the SAVESETUP option of
the main menu sets the Delay to zero seconds.
As can be seen in the flowchart, there is a path that allows
operation to loop around the source. When Source Bypass is
enabled (Scan Trigger Control set to Source) and the event
source is External or Trigger Link, operation loops around
the source on the initial pass through the scan layer. If
programmed for another scan (scan count > 1), the bypass
loop is not in effect even though it is still enabled. The
Source Bypass loop resets (is in effect) if operation goes
back into the arm layer.
Enabling Source Bypass also enables the Output Trigger.
When operation returns to the scan layer from the measure
layer, an output trigger pulse occurs. If the event source is
Trigger Link, an output trigger pulse is available on the
programmed TRIGGER LINK output line. For all other
event sources, the output trigger pulse is available at the
METER COMPLETE connector. The Output Trigger in this
layer is disabled when Source Bypass is disabled (Scan
Trigger Control set to Acceptor).
After all other operations in the next layer are complete, the
instrument can be returned to the scan layer by programming
2001-900-01 Rev. K/ August 2010
NOTE
the instrument for additional scans. The Scan Count option
is used to set the scan count to a finite value (where n = 1 to
99999) or for an infinite number of scans. Selecting BENCH
RESET from the SAVESETUP option of the main menu sets
the scan count to infinite; selecting GPIB RESET sets the
scan count to one.
After the instrument leaves the scan layer, operation
proceeds into the measure layer (trigger layer).
Measure layer
For bus operation, this layer is called Trig-
ger.
In general, measure events control the measurement (or
scan) rate. With a measure source of Immediate, operation
immediately proceeds to the Delay. Selecting BENCH or
GPIB RESET from the SAVESETUP option of the main
menu also sets the measure source to Immediate. With one of
the other sources selected, the instrument waits until the
appropriate event occurs:
• With the External source selected, the instrument waits
for an input trigger via EXTERNAL TRIGGER on the
rear panel.
• With the Manual source selected, the instrument waits
until the front panel TRIG key is pressed.
• With the GPIB source selected, the instrument waits for
a bus trigger (GET or *TRG).
• With the Trigger Link source selected, the instrument
waits for an input trigger via TRIGGER LINK on the
rear panel.
• With the Timer source selected, the first measurement
occurs immediately. Each additional measurement
occurs at a rate determined by the programmed timer
interval (1msec to 999999.999sec).
• With the HOLD source selected, the instrument does
not respond to any of the event sources. Another source
must be selected to acquire a reading.
With the Immediate trigger source select-
ed, a "trigger ignored" message will be
displayed if an external trigger is sent to
the Model 2001 or a manual trigger (i.e.,
pressing TRIG key) occurs. The external
or manual trigger is not used (ignored).
After the programmed measure event is detected, the
instrument waits for the programmed Delay to time out. The
measure layer Delay can be set from 0 to 999999.999sec.
Front Panel Operation
NOTE
NOTE
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