Keithley 2001 Operator's Manual page 183

grammed timer interval elapses. The timer can be set to an
interval from 1msec to 999999.999 seconds.
With the Manual
(:ARM:LAYer2:SOURce MANual), the instrument will wait
until the front panel TRIG key is pressed. Note that the
Model 2001 must be taken out of remote (press LOCAL key
or send LOCAL 716 over bus) before it will respond to the
TRIG key. With the Bus control source selected
(:ARM:LAYer2:SOURce BUS), the instrument will wait
until a bus trigger is received (GET or *TRG). With the
External control source selected (:ARM:LAYer2:SOURce
EXTernal), the instrument will wait until an input trigger (via
EXTERNAL TRIGGER connector on rear panel) is
received. With the Trigger Link control source selected
(:ARM:LAYer2:SOURce TLINk), the instrument will wait
until an input trigger is received (via TRIGGER LINK).
With the Hold
(:ARM:LAYer2:SOURce HOLD), the instrument will not
respond to any of the control source events.
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 (ie.,
pressing TRIG key) occurs. The external
or manual trigger is not used (ignored).
After the programmed scan event is detected, the instrument
will wait for the programmed Delay to time out. The
:ARM:LAYer2:DELay <num> command is used to set the
Delay (where num = 0 to 999999.999 seconds). The *RST
and :SYSTem:PRESet commands set the Delay to zero
seconds.
As can be seen in the flowchart, there are three paths that al-
low operation to loop around the control source. Two of
these paths also loop around the Delay. These three paths are
described as follows:
1. When the Source Bypass is enabled (:ARM:TCONfig-
ure:DIRection SOURce) and the External or Trigger
Link control source is selected, operation will loop
around the control source on the initial pass through arm
layer 2. If programmed for another scan (scan count >
1), the bypass loop will not be in effect even though it
will still be enabled. The Source Bypass loop will reset
(be in effect) if operation goes back into arm layer 1.
2. Enabling the Source Bypass also enables the Output
Trigger. When operation returns to arm layer 2 from the
trigger layer, an output trigger pulse will occur. If the
Trigger Link control source is selected, the output
2001-900-01 Rev. K/ August 2010
control source selected
control source selected
NOTE
trigger pulse will be available on the programmed
TRIGGER LINK output line. For all other control
source selections, the output trigger pulse will be
available at the METER COMPLETE connector. The
Output Trigger in this layer is disabled when the Source
Bypass is disabled (:ARM:TCONfigure:DIRection
ACCeptor).
3. Each time the :ARM:LAYer2:IMMediate command is
sent, operation will loop around the scan control source
and the Delay. It is used when you do not wish to wait
for a programmed scan event to occur (or when the Hold
control source is selected).
4. Each time the :ARM:LAYer2:SIGNal command is sent,
operation will loop around the scan control source. This
path functions the same as :ARM:LAYer2:IMMediate
except that it does not loop around the Delay.
After all other operations in the next layer have been com-
pleted, the instrument can be returned to arm layer 2 by pro-
gramming the instrument for additional scans. The
:ARM:LAYer2:COUNt
used to set the scan count to a finite value (where n = 1 to
99999) or for an infinite (INF) number of scans. The *RST
command sets the scan count to one and the :SYSTem:PRE-
Set command sets the scan count to infinite.
After the instrument leaves arm layer 2, operation proceeds
to the measure layer (trigger layer).
Trigger layer
For front panel operation, this layer is
called the measure layer.
In general, measure events control the
measurement (or scan) rate. With the Im-
mediate control source selected (:TRIG-
ger:SOURce IMMediate),
immediately proceeds to the Delay. The
*RST command also sets the measure
control source to Immediate. With one of
the other control sources selected, the in-
strument will wait until the appropriate
event occurs.
With the Timer control source selected (:TRIGger :SOURce
TIMer), the first measurement will occur immediately. Each
additional measurement will occur at a rate determined by
the programmed timer interval (1msec to 999999.999 sec-
onds).
IEEE-488 Reference
<n>|INFinite command can be
NOTE
operation
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