Keithley 2001 Operator's Manual page 88

Front Panel Operation
Idle
The instrument is considered to be in the idle state whenever
it is not operating within one of the three layers of the Trigger
Model. The front panel ARM indicator is off when the
instrument is in the idle state. While in the idle state, the
instrument cannot perform any measurement or scanning
functions.
From the front panel there are four ways to put the
instrument into idle:
• Select RESET GPIB from the SAVESETUP option of
the main menu. Press the TRIG key to take a reading.
After each reading, the instrument returns to the idle
state.
• Select HALT from the CONFIGURE TRIGGER menu.
Press the TRIG key to resume triggering.
• Enable BURST-MODE from the CONFIGURE DATA
STORE menu. This places the instrument in idle until
the TRIG key is pressed. After each burst acquisition
the instrument returns to idle.
• Configure an internal or external scan with the SCAN
key. Disabling the scan resumes triggering.
Once the instrument is taken out of the idle state, operation
proceeds into the arm layer (arm layer 1) of the Trigger
Model.
Arm layer
For bus operation, this layer is called arm
layer 1.
In general, the instrument requires an arm event to allow
operation to proceed to the next layer (scan layer). With an
arm source of Immediate, operation proceeds to the next
layer when the instrument is taken out of the idle state.
Selecting BENCH or GPIB RESET from the SAVESETUP
option of the main menu also sets the arm 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.
3-56
NOTE
• 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).
As can be seen in the flowchart, there is a path that allows
operation to loop around the source. When Source Bypass is
enabled (Arm 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 arm layer. If
programmed for another arm (arm 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 into
Idle.
Enabling Source Bypass also enables the Output Trigger.
When operation returns to the arm layer from the scan 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 (Arm Trigger Control set to
Acceptor).
After all other instrument operations are complete, the
instrument can be returned to the arm layer by programming
the instrument for additional arms. The Arm Count option is
used to set the arm count to a finite value (where n = 1 to
99999) or for an infinite number of arms. Selecting BENCH
or GPIB RESET from the SAVESETUP option of the main
menu sets the arm count to one.
After the instrument leaves the arm layer, operation proceeds
into the scan layer (arm layer 2).
Scan layer
For bus operation, this layer is called arm
layer 2.
In general, the instrument requires a scan event to allow
operation to proceed to the next layer (measure layer). With
a scan source of Immediate, operation immediately proceeds
to the next layer. Selecting BENCH or GPIB RESET from
the SAVESETUP option of the main menu also sets the scan
source to Immediate. With one of the other sources selected,
the instrument waits until the appropriate event occurs:
2001-900-01 Rev. K/ August 2010
NOTE
NOTE