Trigger Layer; Trigger Delay; Source, Delay, And Measure Actions - Keithley 2500 User Manual

Models 2500 and 2502 User's Manual

Trigger layer

The Trigger Layer uses three event detectors; one for each action (Source, Delay, and
Measure).
Event Detector Bypass — As shown in
Event Detector. This bypass is in effect only if Trigger Link is the selected Trigger-In
Source. With this event detector bypass set to ONCE, operation will proceed around the
Source Event Detector.
The programmable trigger-in sources for the Trigger Layer are described as follows:
IMMEDIATE — With Immediate selected, event detection for the three detectors is satis-
fied immediately. Operation proceeds through the Trigger Layer to perform the Source,
Delay, and Measure actions.
TRIGGER LINK — With Trigger Link selected, event detection at each enabled detector
occurs when an input trigger via the Trigger Link input line is received. For example, if the
Trigger In Event for the Source Event Detector is ON, operation will hold up at that detec-
tor until an input trigger is received. If, however, the Source Event Detector is disabled
(OFF), operation will not hold up. Operation will simply continue and perform the Source
action.
With the Trigger Link Trigger-In Source selected, operation will go around the Source
Event Detector

Trigger delay

A programmable delay is available before the Source Action. The Trigger Delay can be
manually set from 0.00000 to 999.99990 seconds. Note that this delay is separate from the
Delay Action of the SDM cycle. The Delay Action is discussed next.

Source, delay, and measure actions

The SDM cycle of the Model 2500 consists of three actions: Source, Delay, and Measure:
SOURCE Action — Any programmed output voltage level changes are performed.
DELAY Action — This programmable delay is used to allow the source to settle before a
measurement is performed. It can be manually set from 0.00000 to 9999.99800 seconds,
or Auto Delay can be enabled. With Auto Delay enabled, the Model 2500 automatically
selects a nominal delay period based on the selected current measurement range.
NOTE
MEASURE Action — During this phase of the SDM cycle, the measurement process
takes place. If the repeat filter is enabled, as shown in the blow-up drawing for Measure
Action, the instrument samples the specified number of reading conversions to yield a sin-
gle filtered reading (measurement). If using the moving filter or if the filter is disabled,
only a single reading conversion will yield a reading.
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(Figure 10-1) by setting the event detector bypass to ONCE.
The Delay Action is set from the CONFIGURE SRC1 or CONFIGURE SRC2
menu. See Section 3, "Source delay."
Figure 10-1, there is a bypass for the Source
Triggering 10-5