Keysight N1911A Programming Manual page 226

4 CALibration Subsystem
Query
CALibration[1]|2:ZERO:AUTO?
The query always returns a value of 0.
Error Messages
– If this command is set to ON and an 8480 Series, E-Series or N8480 Series
– If zeroing was not carried out successfully the error –231, "Data Questionable;
– If there is no sensor connected, the error –241, "Hardware Missing" occurs.
– If this command is set to ON and TRIGger[:SEQuence[1]|2]:COUNt setting is
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power sensor is connected the error –241, "Hardware missing" occurs.
ZERO ERROR" occurs. If you are using an N1912A, the error message specifies
which channel failed zeroing.
more than 1, the error –221, "Setting conflict" occurs.
N1911A/1912A P-Series Power Meters Programming Guide