3-54 Basic DMM Operation Model 2700 Multimeter/Switch System User’s Manual
DATA[:LATest]?
DATA:FRESh?
These commands do not trigger a reading. They simply return the last reading
string. The reading reflects what is applied to the input.
While the instrument is performing measurements, you can use these
commands to return the last reading. If the instrument is not performing
measurements, DATA[:LATest]? will keep returning the same reading string.
DATA:FRESh? can only be used once to return the same reading string. That
is, the reading must be “fresh.” Sending this command again to retrieve the
same reading string will generate error -230 (data corrupt or stale), or cause a
the GPIB to time-out. In order to again use DATA:FRESh? a new (fresh)
reading must be triggered.
FETCh?
READ?
FETCh? is similar to DATA[:LATest]]? in that it can be used to return the last
reading. However, it can also be used to return more than one reading. When
returning more than one reading, the readings are automatically stored in the
buffer.
In order to return multiple reading strings, continuous initiation must be
disabled (INIT:CONT OFF) so that the sample count (SAMPle:COUNt),
which specifies the number of measurements to be performed, can be set >1.
After INITiate is sent to trigger the measurements, FETCh? will return the
reading strings.
In general, READ? performs an INIT to trigger measurements and then a
FETCh? to retrieve the reading strings. With continuous initiation disabled
(INITiate:CONTinuous OFF), you can use the READ? command to trigger
and return readings. The sample count determines the number of reading
strings to be returned. With the sample count >1, the returned readings are
automatically stored in the buffer.
NOTE When readings are stored in the buffer by the TRACe command (or
by front panel data store operation), INIT and multi-sample READ?
queries are locked out. With readings in the buffer that were stored
in that manner, you cannot use the INIT or READ? command if sam
-
ple count is >1 (error -225, out of memory). Buffer operation is cov-
ered in Section 6.
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