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Model 2750 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 sam-

ple 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

) 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 trig-

ger 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 read-

ing 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.

FETCh?

READ?

MEASure?

CALC[1]:DATA[LATest]?

CALC[1]:DATA:FRESh?

As shown in Figure D-4, these commands are used to read data arrays output from the

CALC1 Math block. However, if there is no Math function enabled, these commands read

the data arrays in the sample buffer.

2750-900-01.book Page 9 Wednesday, August 3, 2011 7:56 AM

Keithley 2750 User Manual

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