6-6
IM 701310-17E
6.5 Output Queue and Error Queue
Output Queue
The output queue is provided to store response messages to queries. For example, if
you send the WAVeform:SEND? command, which requests the output of acquired data,
the data is stored in the output queue until it is read.
As shown below, data are stored in order and read from the oldest ones 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 5-2).
• 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 byt.
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 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 instrument is power cycled.
To see whether the error queue is empty or not, check bit 2 (EAV) of the status byte.
