User manual

IEEE-488 Reference
4-208 2001-900-01 Rev. K / August 2010
Description This command is used to specify how much of the defined buffer (:POINts) will be used to store
pre-triggered readings. When a pre-trigger store is started (see :FEED:CONTrol), readings will
continuously be stored in the buffer. When the pre-trigger event occurs (see
:PRETrigger:SOURce), post-trigger readings will then fill the part of the buffer that is not
reserved for pre-trigger readings.
For example, assume 25% of a 100 point buffer is reserved for pre-trigger readings. When the
pre-trigger store is started, readings will continuously fill the buffer. When the pre-trigger event
occurs, subsequent readings will then be stored starting at buffer location 26 and continuing un-
til buffer location 100 is filled. Storage stops after buffer location 100 is filled. The result is 25
pre-trigger readings and 75 post-trigger readings.
Programming example 10 OUTPUT 716; “:trac:feed:pret:amo 25; amo?”
20 ENTER 716; A$
30 PRINT A$
40 END
Line 10 Two commands in this program message; the first specifies that 25% of the buffer
will be used for pre-trigger readings, and the second queries the percentage.
Line 20 Addresses the Model 2001 to talk.
Line 30 Displays the percentage of the buffer to used for pre-trigger readings (25).
:READings [BUFFER,] <n>
:TRACe:FEED:PRETrigger:AMOunt:READings [BUFFER,] <n>Specify number of pre-trigger read-
ings
Parameters No memory
Option MEM 1 MEM 2
<n> = 0 to 250 0 to 1400 0 to 6000 (Full)
= 0 to 850 0 to 7000 0 to 30000 (Compact)
= MAXimum Present buffer size (TRACe:POINts)
= DEFault Half present buffer size (TRACe:POINts)
= MINimum 0
Format :trac:feed:pret:amo:read <n>
Defaults Power-up 5
*RST No effect
:SYSTem:PRESet No effect
Query :READ? [BUFFER,]
Short-form formats: :trac:feed:pret:amo:read?
Response message: 0 to 30000
Description This command is used to specify how much of the defined buffer (:POINts) will be used to store
pre-triggered readings. This command is essentially the same as the :PERCent command except
the amount is expressed as an exact value instead of a percent.