3-49
Error messages
Error handling
Error messages are divided into four groups:
(1) Background
errors
−
represent a condition of the instrument.
(2) Foreground
errors
−
generally caused by the user.
(3) GPIB
errors
−
generated by incorrect programming.
(4) Fatal
errors
−
caused by failure associated with the main RAM or the
PROM. These errors may or may not be displayed according
to the severity of the failure or corruption.
Background errors:
These are generated due to an incorrect operating condition within the instrument. These errors are
generated automatically to warn the operator. For example if the reverse power protection circuit
should trip the message:
Err 500: RPP tripped
will be displayed on the main screen. Background
errors are listed in
Table 3-2
. Only one error will be displayed, that with the highest priority. To
obtain a full list of errors occurring on your instrument in priority order, select
[Backg’nd Errors]
from the
Utilities Selection Menu 1
. This causes the
Current Background Errors
screen to be
displayed (see
Fig. 3-30
). Select
[Next Page]
if the list is continued on a subsequent page.
Foreground errors:
These are typically generated when an entered parameter value is outside the valid range or for
some other invalid operation. For example trying to set the carrier frequency above or below the
specified range will display the following message
Err 100: Carrier limit
on the screen. The
foreground errors are cleared upon function selection or by re-entering the parameter correctly.
Foreground errors are listed in
Table 3-3
.
Error message priority:
A background error has a priority bit set which is used to determine which message needs to be
displayed. A foreground error will temporarily overwrite the background error if currently
displayed, but will return to displaying that error once the foreground error has been cleared.
GPIB errors
When an error occurs the error number is put into the error queue and the error message is
displayed. Clearing the error message from the screen does not clear the error queue, which is only
cleared by the GPIB command ERROR? query, which returns the error at the head of the queue, or
by the *CLS command which clears the whole error queue. GPIB errors are listed in
Table 3-4.
The queue holds a maximum of 64 error message error numbers. If an error occurs while the
queue is full the last error number is replaced with 399 to indicate that the queue is full. The
ERROR? query returns a value of 399 for queue full and 0 for queue empty.
When an error number is written into the queue, a bit (<erb>) in the status byte register is set, and
an appropriate bit in the standard event register is also set (one of <cme>, <exe>, <dde> or <qye>).
These errors will also generate SRQ if the relevant bit in the status register is set. Many
background errors are also reported in the Hardware and Coupling Status Registers.
