10-40
IM 755601-01E
10.3.5
Output Queue and Error
Queue
Output Queue
The output queue stores response messages for the
queries. For example, when the controller sends a
:READ?
command requesting the output of measured
data, data are stored in the output queue until they are
read.
As shown in the figure 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 10-2)
• 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 the
*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.
10.3 Status Report
