Keithley 2700, User Manual, Page: 187 / 500

5-14 Rel, Math, Ratio, Channel Average, dB Model 2700 Multimeter/Switch System User’s Manual
Setting mX+b units
The <char> parameter for CALCulate:KMATh:MUNits must be one character enclosed in
single or double quotes. It can be any letter of the alphabet, the degrees symbol (°) or the
ohms symbol (
Ω
).
The ohms symbol (
Ω
) and the degrees symbol (°) are not ASCII characters and therefore,
must be substituted with the ‘[’ and ‘\’ characters as follows:
CALCulate:KMAth:MUNits ‘[’ Use ohms symbol (
Ω
) as units designator.
CALCulate:KMAth:MUNits ‘\’ Use degrees symbol (°) as units designator.
Percent reference
The :PERCent <NRf> command specifies the reference value for the percent calculation,
while the :PERCent:ACQuire command uses the input signal as the reference value.
The :ACQuire command is only functional if a reading is available. If the instrument is
overflowed (“OVERFLOW”), or a reading has not been triggered (“------”), an execution
error (-200) occurs when :ACQuire is sent.
The :PERCent <NRf> command is coupled to the :PERCent:ACQuire command. When a
reference value is set using :PERCent <NRf>, the :PERCent? query command returns the
programmed value. When reference is set using :ACQuire, the :PERCent? query
command returns the acquired reference value.
Reading math result
CALCulate[1]:DATA[:LATest]? or CALCulate:DATA:FRESh? can be used to retrieve the
result of the selected math calculation. These commands do not trigger a reading. They
simply return the last reading string. The reading reflects the result of the calculation.
While the instrument is performing measurements, you can use these commands to return
the last reading. If the instrument is not performing measurements, CALC:DATA? will
keep returning the same reading string.
CALC: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 the GPIB to time-out. In order to
again use DATA:FRESh? a new (fresh) reading must be triggered.
If math is disabled (CALCulate:FORMat NONE or CALCulate:STATe OFF), the “raw”
reading will be retrieved by CALC:DATA? and CALC:DATA:FRESh?.