Keithley 2700, Руководство пользователя, Страница: 428 / 500

Model 2700 Multimeter/Switch System User’s Manual Signal Processing Sequence and Data Flow D-9
[SENS[1]]:DATA[LATest]?
[SENS[1]]:DATA:FRESh?
These commands are used to return (read) the last processed data array stored in the
sample buffer.
[SENS[1]]:DATA[:LATest]?
This command returns (reads) one data array. It returns the last processed data array stored
in the sample buffer. If, for example, 10 data arrays are stored in the sample buffer, only
the last (10
th
) data array is returned.
DATA? does not affect data in the sample buffer. Therefore, subsequent executions of
DATA? acquires the same data array. In order to return a new reading, you must first
trigger a new reading(s) and then use DATA?.
When using DATA? to retrieve data, it is good practice to include reading numbers in the
data arrays. Reading numbers that do not change will indicate that the same data array is
being returned.
NOTE
The FORMat:ELEMents command (see Section 14 ) is used to include the
reading number (RNUM) element in each data array.
[SENS[1]]:DATA:FRESh?
This command is similar to DATA[:LATest]? in that is also returns the last processed data
array stored in the buffer. However, it can only be used once to retrieve the same data
array. That is, the data array reading must be “fresh.” Sending this command again to read
the same (stale) data array will not work. It will generate an error (-230; data corrupt or
stale) or cause the GPIB to time-out. In order for DATA:FRESh? to respond, you must first
trigger a new (fresh) reading.
Using this command to retrieve data ensures that only new (fresh) readings are returned
(no readings are repeated). However, as previously noted, problems may occur if a new
reading is not ready (available) when this command is executed.