16-48
IM 765501-01E
16.3.6 Output Queue and Error
Queue
Output Queue
The output queue is provided to store response
messages to queries.
The example below shows that data is stored record
by record in the output queue, and is read out oldest
item first. The output queue is emptied in the following
cases (in addition to when read-out is performed).
• When a new message is received from the
controller.
• When a deadlock occurs (see page 16-3).
• When a device clear command (DCL or SDC) is
received.
• When the instrument is power cycled.
The output queue cannot be emptied using the *CLS
command. To see whether the output queue is empty
or not, check bit 4 (MAV) of the status byte.
D1
D2
D1
D2
D1
Error Queue
The error queue stores the error No. and message
when an error occurs. For example, if the controller
sends an incorrect program message, the error
number and message “–113, “Undefined header”” are
stored in the error queue when the error is displayed.
The contents of the error queue can be read using the
SYSTem:ERRor? query. As with the output queue, the
messages are read from the oldest ones first.
When the error queue overflows, the last message is
replaced by the message “–350, “Queue overflow”.”
The error queue is emptied in the following cases (in
addition to when read-out is performed).
• When a *CLS command is received.
• When the instrument is power cycled.
To see whether the error queue is empty or not, check
bit 2 (EAV) of the status byte.
16.3 Status Reports
