HP E4418B Programming Manual page 177

MEASurement Instructions
READ[1|2][:SCALar][:POWer:AC]:RELative? [<expected_value>[,<resolution>[,<source list>]]]
Error Messages
INITiate:CONTinuous must be set to OFF, otherwise error -213, "INIT
ignored" occurs.
If TRIGger:SOURce is set to BUS or HOLD, error -214, "Trigger deadlock"
occurs.
If the expected value and resolution parameters are not the same as the
current expected value and resolution settings on the specified window,
error -221, "Settings conflict" occurs.
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