Agilent Technologies ESA-E Series Programmer's Manual page 346

Error Messages
-499 to -400 : Query Errors
-499 to -400:
Query Error s
The instrument output queue control has detected a problem with the
message exchange protocol described in IEEE 488 .2, Chapter 6 . Errors
in this class set the query error bit (bit 2) in the event status registe r
(IEEE 488.2, section 11 .5.1) . These errors correspond to message
exchange protocol errors described in IEEE 488 .2, 6.5.
In this case, either an attempt is being made to read data from th e
output queue when no output is either present or pending, or data in
the output queue has been lost.
- 430
Query DEADLOCKE D
Indicates that a SCPI output queue has filled ,
preventing further SCPI command execution, and ther e
is no more room left in the corresponding SCPI input
queue to accept a query to read from the output queue .
The system automatically discards output to correct th e
deadlock .
- 400
Query Error
This is a generic query error for devices that canno t
detect more specific errors. The code indicates only that
a query error as defined in IEEE 488 .2, 11.5.1.1 .7, and
6.3 has occurred .
-410 Query INTERRUPTED
Indicates that a condition causing an INTERRUPTE D
query error occurred (see IEEE 488 .2, 6 .3.2.7). For
example, a query was followed by DAB or GET before a
response was completely sent .
-420
Query UNTERMINATE D
Indicates that a condition causing a n
UNTERMINATED query error occurred (see IEE E
488.2, 6 .3.2.2). For example, the device was addresse d
to talk and an incomplete program message was
received .
7-18 Chapter 7