BNC 1201 - 6 1/2 Digit Digital Multimeter - Manual (Page 130)

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531 Insufficient memory
There is not enough memory to store the requested number of readings
in internal memory using the INITiate command. The product of the
sample count (SAMPle:COUNt) and the trigger count (TRIGger:COUNt)
must not exceed 512 readings.
532 Cannot achieve requested resolution
The multimeter cannot achieve the requested measurement resolution.
You may have specified an invalid resolution in the CONFigure or
MEASure command.
540 Cannot use overload as math reference
The multimeter cannot store an overload reading (9.90000000E+37) as
the math reference for null or dB measurements. The math state is
turned off as a result of this condition.
550 Command not allowed in local
The multimeter received a READ? Command while in the local mode.