HP 53181A Programming Manual page 285

Errors
Error Queue
10 ASSIGN @Cntr TO 703
20 !Assign path name
30 DIM Err_string$[255]
40 !Creates array for error string
50 REPEAT
60 !Repeats until error queue is empty
70 OUTPUT @Cntr;"SYST:ERR?"
80 !Read error number and string
90 ENTER @Cntr;Err_num,Err_string$
100 !Enter error number and string
110 PRINT Err_num,Err_string$
120 !Print error number and string
130 UNTIL Err_num = 0
140 END
Error Queue
As errors are detected, they are placed in an error queue. This queue is first in, first
out. That is, if there has been more than one error, the first one in the queue is read
out with :SYST:ERR?. Subsequent responses continue until the queue is empty.
If the error queue overflows, the last error in the queue is replaced with error
"Queue overflow". Any time the queue overflows, the least recent errors remain
in the queue, and the most recent error is discarded. The length of the Counter's
error queue is 30 (29 positions for the error messages, and 1 position for the "Queue
overflow" error). Reading an error from the head of the queue removes that error
from the queue, and opens a position at the tail of the queue for a new error, if one
is subsequently detected.
When all errors have been read from the queue, further error queries return +0,
"No error".
The error queue is cleared when any of the following occur:
• Upon power-on.
• Upon receipt of a *CLS command.
• Upon reading the last item from the queue.
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