Keithley 6485, User Manual

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6-4 Buffer and Sweeps Model 6485 and 6487 User’s Manual
NOTE If any readings stored in the buffer are the result of an overflow or Model 6487
overvoltage condition, the buffer statistics calculation will not be performed.
Buffer recall via front panel operation will show a series of dashes in place of
the requested buffer statistics value. In remote operation, the corresponding
buffer statistics will be represented by the value +9.91e37.
SCPI programming — buffer
Table 6-1
SCPI commands — buffer
Commands Description
TRAC:CLE
TRAC:FREE?
TRAC:POIN <n>
TRAC:POIN:ACT?
TRAC:FEED <name>
TRAC:FEED:CONT <name>
TRAC:TST:FORM <name>
TRAC:DATA?
FORM:ELEM <list>
CALC3:FORM <name>
CALC3:DATA?
Clear readings from buffer.
Query bytes available and bytes in use.
Specify number of readings to store: 1 to 2500, Model 6485;
1 to 3000, Model 6487.
Returns number of readings actually stored in buffer.
Select source of readings for buffer: SENS, CALC1, or CALC2.
Select buffer control mode: NEV or NEXT.
Select timestamp format: ABS or DELT.
Read all readings in buffer.
Specify data elements for TRAC:DATA? response message:
READ, UNIT, VSO, TIME, and STAT (VSO, 6487 only).
Select buffer statistic: MIN, MAX, MEAN, SDEV, or PKPK.
Read the selected buffer statistic.
Programming example
The following command sequence stores 20 readings into the buffer and then calculates
the mean average on the buffer readings:
' Select data elements:
*RST
' Return 6485/6487 to RST defaults.
FORM:ELEM READ,TIME ' Select reading and timestamp.
' Store and Recall Readings:
TRIG:COUN 20
' Set trigger model to take to 20
readings.
TRAC:POIN 20 ' Set buffer size to 20.
TRAC:FEED SENS ' Store raw input readings.
TRAC:FEED:CONT NEXT ' Start storing readings.
SYST:ZCH OFF ' Turn off zero check.
INIT ' Trigger readings.
TRAC:DATA? ' Request all stored readings.
' Acquire Mean Statistic for Buffer Readings:
CALC3:FORM MEAN
' Select mean statistic.
CALC3:DATA? ' Request mean statistic.