Keithley 2700 - Page 179

5-6 Rel, Math, Ratio, Channel Average, dB Model 2700 Multimeter/Switch System User’s Manual
“Pressing REL” using rel commands
When the front panel REL key is pressed, the displayed reading is used as the rel value.
Subsequent readings are then the result of the actual input value and the rel value.
The :REFerence:ACQuire and :REFerence:STATe ON commands (in that order) can be
used to “press” the REL key. For example, the following command sequence is the
equivalent of pressing the REL key while on the DCV function:
VOLT:REF:ACQ ' Acquire reading as rel value.
VOLT:REF:STAT ON ' Enable rel.
Setting rel values
The :REFerence <n> command specifies the rel value for the specified function, while the
:ACQuire command uses the input signal as the rel value. The :ACQuire command is
typically used to zero the display. For example, if the instrument is displaying a 1µV
offset, sending :ACQuire and enabling rel (STATe ON) zeroes the display.
The ACQuire command is only functional if the instrument is on the specified function.
For example. If the instrument is on the DCV function, the only valid acquire command is
VOLT:DC:REF:ACQ. Also, if the instrument is overflowed (“OVERFLOW”), or a read
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ing has not been triggered (“------”), an execution error (-200) occurs when :ACQuire is
sent.
The :REFerence <n> command is coupled to the ACQuire command. When a rel value is
set using :REFerence <n>, the :REFerence? query command returns the programmed
value. When rel is set using :ACQuire, the :REFerence? query command returns the
acquired rel value.