9-2
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6482-901-01 Rev. A / August 2012
Section 9: Measurement Concepts
Model 6482 Dual-Channel Picoammeter / Voltage Source Reference Manual
Source-delay-measure cycle
Overview
Model 6482 voltage bias and measurements operation for each channel can consist of a series of
source-delay-measure (SDM) cycles (
). During each SDM cycle, the following occurs:
1. Set the voltage bias source output level.
2. Wait for the programmed delay period.
3. Make the measurement.
Figure 9-1
Source-delay-measure (SDM) cycle
Triggering
shows how the SDM cycle fits into the trigger model. See
for complete details
on the trigger model. When the source is turned on (triggered), an approximate 100 µs trigger
latency occurs before the programmed source level is output. If the source output stays on, trigger
latency will not be included in subsequent SDM cycles. Trigger latency only occurs when the
output makes the transition from off to on. For the latest specifications, visit the Keithley
Instruments website (http://www.keithley.com). The specifications include trigger latency
definitions and other trigger specifications.
Figure 9-2
Simplified trigger model
Measure
Delay
Start of analog to digital
conversion
End of analog to digital
conversion
Trigger
latency
(100
μ
s)
Source
value
Trigger
Event
Event
Idle
S D M
Delay Measure
Arm
Trigger
layer
Trigger
Trigger
Source
Arm
layer
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