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MAX selects 1 billion readings. However, when pretrigger is selected, the maximum is 50,000 readings
(
without
the MEM option) or 2,000,000 readings (
with
the MEM option).
l
This parameter is set to its default value after a Factory Reset (
) or Instrument Preset
(
).
SAMPle:COUNt:PRETrigger {<
count
>|MIN|MAX|DEF}
SAMPle:COUNt:PRETrigger? [{MIN|MAX|DEF}]
Allows collection of the data being digitized
before
the trigger. Reserves memory for pretrigger samples
up to the specified number of pretrigger samples.
It is recommended that all triggered measurements be made using an appropriate fixed
manual range. That is, turn autorange off (
SENSe:<function>:RANGe:AUTO OFF
), or set
a fixed range using the
,
, or
command.
Parameter
Typical Return
0 to 1,999,999. Default: 0.
+999999
Configure AC voltage measurements using the 100 V range. Set the sample count to 10,000 and the pre-
trigger sample count to 5000 (5000 samples are taken before the trigger, and 5000 after). The trigger
occurs when the input signal reaches 0.75 volts.
CONF:VOLT:AC
VOLT:AC:RANG 100
SAMP:COUN 10000
SAMP:COUN:PRET 5000
TRIG:SOUR INT
TRIG:LEV 0.75
INIT
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Applies only to the 34465A and 34470A.
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Pretrigger applies to all measurement functions except CONTinuity and DIODe test.
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Use
to set the
total
number of samples to take, then use SAMPle:COUNt:PRETrigger
to set the number of pretrigger samples to take.
For example, with a sample count of 50,000, and a pretrigger sample count of 20,000, up to 20,000
samples are taken before the trigger, then 30,000 samples are taken after the trigger occurs.
The sample count and pretrigger count do not affect when the trigger occurs. If the memory allocated
for pretrigger samples fills up, the oldest readings are discarded. In the example above, the 20,000
most recent
pretrigger samples are saved, even if more than 20,000 samples occur before the trigger.
If the trigger occurs
before
the pretrigger count is satisfied, only the actual pretrigger samples taken
are saved.
In all cases, after the trigger is received, only
sample count
minus
specified pretrigger count
readings
are taken. In this example, if the trigger occurs after 5 pretrigger samples have been taken (instead of
the specified 20,000), only 30,000 post-trigger samples are taken. This is because memory was
reserved for 20,000 pretrigger samples.
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If a trigger occurs during a measurement, that measurement is considered to be a pretrigger sample.
Keysight True
volt
Series Operating and Service Guide
307
SCPI Programming Reference
