15 READ Subsystem198 Keysight U2040 X-Series Programming GuideREAD[1]|2|3|4[:SCALar][:POWer][:AC]:DIFFerence:RELative?SyntaxREAD[1]|2|3|4[:SCALar][:POWer][:AC]:DIFFerence:RELative?[[,[,]]]DescriptionThis query sets the specified CALCulate block measurement function to the differencemode with relative mode on, aborts then initiates Channel A, calculates the differencemeasurement result, and places the result on the bus. The result is a ratio-basedmeasurement and is expressed in the units defined by UNIT[1]|2|3|4:POWer:RATio.The relative value used is that set by the CALCulate:RELative:MAGNitude:AUTOcommand.ParametersNOTE INITiate:CONTinuous must be set to OFF, otherwise error –213, “INIT ignored” occurs.If TRIGger:SOURce is set to BUS, error –214, “Trigger deadlock” occurs.Item Range of values Description/Default valueexpected_value(for the expected powerlevel)sensor-dependentDEF[a][a] The mnemonic DEF means DEFault. This is not equivalent to the DEFault parameter used in the commandsubsystems. The parameters must be entered in the specified order. If parameters are omitted, they default from theright. The parameter DEFault is used as a placeholder. Specifying DEF leaves the parameter value unchanged.The U2040 X-Series ignores the numeric value entered in thisparameter. Any value entered is treated like DEF.resolution1 to 4[b]1.0, 0.1, 0.01, 0.001DEF[a][b] When SENS:AVER:COUN:AUTO is enabled, the resolution setting affects the number of averages applied. Refer to“Auto-averaging mode” on page 44 for more information.A numeric value for the resolution. If it is unspecified, thecurrent resolution setting is used. If a value is entered, itshould correspond to the current resolution setting otherwisean error occurs.source_list (@1),(@1)This channel list specifies the channels used to calculate thedifference. If unspecified and the current setup is a differencemeasurement, then this difference setup is used, otherwise itdefaults to Channel A-A.
