HP 34401A User Manual page 177

Chapter 5 Error Messages
Execution Errors
501 Isolator UART framing error
502 Isolator UART overrun error
RS-232 framing error
511
RS-232 overrun error
512
513 RS-232 parity error
514 Command allowed only with RS-232
There are three commands which are only allowed with the
interface: SYSTem:LOCal, SYSTem:REMote, and SYSTem:RWLock.
Input buffer overflow
521
522 Output buffer overflow
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.
Cannot use overload as math reference
540
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.
For
command before sending other commands over the interface.
178
operation, you should always execute the SYSTem:REMote
RS-232
RS-232