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IM 704420-01E
8.8.5 Output Queue and Error Queue
Output Queue
The output queue stores response messages for the
queries.
As shown in the example below, data are stored in
order and read from the oldest ones first. The output
queue is also cleared for the following cases:
• When a new message is received from the
controller.
• When a deadlock occurs (see page 8-9)
• When a device clear command (
DCL
or
SDC
) is
received.
• When the power is turned ON again.
The
*CLS
command cannot be used to clear the output
queue. Bit 4 (MAV) of the status byte can be used to
check whether or not the output queue is empty.
D1
D2
D1
D2
D1
Error Queue
The error queue stores the error number and message
when an error occurs. For example, if the controller
sends an incorrect program message, the error
number “
113
” and the message “
Undefined header
”
are stored in the error queue when the error is
displayed.
The
STATus:ERRor?
query can be used to read the
contents of the error queue. 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 also cleared for the following cases:
• When a
*CLS
command is received.
• When the power is turned ON again.
Bit 2 (
EAV
) of the status byte can be used to check
whether or not the error queue is empty.
8.8 Status Report
