Agilent Technologies E4418B User Manual page 171

-420
Query UNTERMINATED
The power meter was addressed to talk (that is, to send data over the interface) but
a command has not been received which sends data to the output buffer. For
example you may have executed a CONFigure command (which does not
generate data) and then attempted to read data from the remote interface.
-430
Query DEADLOCKED
A command was received which generates too much data to fit in the output buffer
and the input buffer is also full. Command execution continues but data is lost.
-440
Query UNTERMINATED after indefinite response
The *IDN? command must be the last query command within a command string.
Agilent E4418B User's Guide
Error Messages
Error Messages
4-11