Keithley KUSB-3100, User Manual

Page: 27 / 129

Principles of Operation
13
2
2
2
2
2
2
2
2
2
Figure 2: Continuous Scan Mode
Input Triggers
A trigger is an event that occurs based on a specified set of
conditions. Acquisition starts when the module detects the initial
trigger event and stops when the specified number of samples has
been acquired (if the buffer wrap mode is none, described on
page
14 ), or when you stop the operation. Note that when you stop the
operation, the module completes the reading of the channel-gain list.
The KUSB-3100 module supports the following trigger sources:
• Software trigger – A software trigger event occurs when you
start the analog input operation (the computer issues a write to
the module to begin conversions). Using software, specify the
trigger source as a software trigger.
• External digital (TTL) trigger – An external digital (TTL) trigger
event occurs when the module detects a high-to-low transition on
the Ext Trig In signal connected to the module. Using software,
specify the trigger source as a falling-edge external digital trigger
(trigger source extra).
Initial trigger event occurs
Chan 0
Chan 1
Chan 2 Chan 0
Chan 1
Chan 2 Chan 0
Chan 1
Chan 2 Chan 0
Chan 1
Chan 2
Input
Sample
Clock
Data acquired continuously