Keithley S46, Инструкция по эксплуатации

Страница: 39 / 63

Document number: S46-901-01 Rev. F / March 2011 3-15
S46/S46T/S46L Microwave Switch System Instruction Manual Section 3: Operation
Output queue
When data is placed in the output queue, the message available bit (MAV) in the Status Byte
Register sets. A data message is cleared from the output queue when it is read. The output queue
is considered cleared when it is empty. A cleared output queue clears the MAV bit in the Status
Byte Register. A message is read from the output queue by addressing the unit to talk after the
appropriate query is sent.
The following command sequence enables the MAV bit (B4) of the Status Byte Register set and
then causes an SRQ:
*SRE 16'Enable MAV bit of the status byte to cause an SRQ.
Language specific 'Send a query command to the instrument.
Language specific 'Wait for an SRQ indicating ready to read.
Language specific'Read the query response.
Error queue
When a message is placed in the error queue, the error available bit (EAV) in the Status Byte
Register sets. An error/status message is cleared from the error queue when it is read. The error
queue is considered cleared when it is empty. A cleared error queue clears the EAV bit in the
Status Byte Register.
Read an error message from the error queue by sending either of the following SCPI query
commands and then addressing the S46/S46T/S46L to talk:
:SYSTem:ERRor?
:STATus:QUEue?
Messages in the error queue are stored in a FIFO (First In-First Out) manner. The commands to
read the error queue are listed in
Table 3-10 . When you read a single message in the error queue,
the oldest message is read and then removed from the queue. If the queue becomes full, the
message “
350, ‘Queue Overflow’
” will occupy the last memory location. When the instrument
power is turned on, the error queue is empty. When empty, the message “
0, No Error
” is placed
in the queue.
Messages in the error queue are preceded by a code number. Negative (-) numbers are used for
SCPI defined messages, and positive (+) numbers are used for Keithley-defined messages. The
error messages are listed in
Table 3-14 .
When the instrument power is turned on, all error messages are enabled and will go into the error
queue as they occur. Status messages are not enabled and will not go into the queue. As listed in
Table 3-10 , there are commands to enable and disable messages. For these commands, the <list>
parameter is used to specify which messages to enable or disable. The messages are specified by
their codes. The following examples show various forms for using the <list> parameter.
<list>=(-110)
Single message
=(-110,-222,-220)
Comma-separated entries
When you enable messages, messages not specified in the list are disabled. When you disable
messages, each listed message is removed from the enabled list.