HP 8920A Programmer's Manual page 271

Accessing the Error Message Queue
A message appears in the Error Message Queue any time bit 2, 3, 4, or 5 of the
Standard Event Status register is asserted. Each message consists of a signed error
number, followed by a comma separator, followed by an error description string
in double quotes. The maximum length of the error description string is 255
characters. If more than 20 messages are in the queue and another error occurs, the
last message is replaced with the message,
messages are in the queue the message,
message removes it from the queue. The Error Message Queue is accessed using
the SYSTem command. Returned information is read into a numeric variable
followed by a string variable.
Reading the Error Message Queue
Syntax
SYSTem:ERRor?
Example
OUTPUT 714;"SYST:ERR?"
ENTER 714;Error_num,Error_msg$
Example IBASIC program
10 INTEGER Error_num
20 DIM Error_msg$ [255]
30 OUTPUT 714;"SYST:ERR?"
40 ENTER 714;Error_num,Error_msg$
50 PRINT Error_num;Error_msg$
60 END
Example response
-113 "Undefined header"
Chapter 5, Advanced Operations
-350,"Queue overflow"
is returned. Reading a
+0,"No error"
Status Reporting
. If no
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