Triggering Sequence - Keithley 6220 Reference Manual

Model 6220/6221 Reference Manual

Triggering sequence

The Trigger Link is used to synchronize source-measure triggering operations of
the Models 6221 and 2182A. See
on Trigger Link connections.
As previously explained, Model 6221 output pulses are synchronized to the fre-
quency of the power line voltage. A low or high pulse is generated on the positive-
going edge of each line cycle.
The triggering sequence for the 3-point measurement method (two lows mea-
sured) is shown in
assumes that the trigger delays for both the Model 6221 and 2182A are set to
zero. Since the trigger delays are zero, they are not shown.
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Figure 5-12
Model 6221 – When Pulse Delta is started from the Model 6221, it outputs
a low (I-Low) current pulse. After the programmed Source Delay of the
Model 6221 expires, an output trigger is sent to the Model 2182A to start its
operations. Source Delay is used to allow the pulse to settle.
NOTE The programmed Pulse Width and Source Delay
determines the integration time for Model 2182A
measurements. The integration time for the Mod-
el 2182A is automatically set when Pulse Delta is
armed.
Model 2182A – The Model 2182A performs a measurement conversion
(A/D #1), and an output trigger is sent back to the Model 6221.
Model 6221 – At the start of the next line cycle, the Model 6221 outputs the
programmed high (I-High) current pulse. After the Source Delay expires, an
output trigger is sent back to the Model 2182A.
Model 2182A – The Model 2182A performs a measurement conversion
(A/D #2), and an output trigger is sent back to the Model 6221.
Model 6221 – At the start of the third line cycle, the Model 6221 again out-
puts the programmed low (I-Low) current pulse. After the Source Delay
expires, an output trigger is sent back to the Model 2182A.
Model 2182A – If measuring the second low pulse, the Model 2182A per-
forms another measurement conversion (A/D #3) and Pulse Delta is then
calculated by the Model 6221. The Model 2182A sends an output trigger to
the Model 6221 to start the next Pulse Delta cycle (if Pulse Delta count is
>1). Otherwise, Pulse Delta will stop.
flow process from the Model 2182A to the Model 6221.
Return to
Delta, Pulse Delta, and Differential Conductance 5-43
"System connections," on page 5-6
and is explained as follows. Note that this diagram
Figure 5-6
Section 5 topics
for details
shows the data (reading)