GPIB Interface
Programming the Polarization Controller
Agilent
8169A
Polarization Controller, Second Edition
45
The Output Queue
The output queue contains responses to query messages. The polarization
controller transmits any data from the output queue when a controller
addresses the instrument as a talker.
Each response message ends with a LF (0A16), with EOI=TRUE. If no query
is received, or if the query has an error, the output queue remains empty.
The Message Available bit (MAV, bit 4) is set in the Status Byte register
whenever there is data in the output queue.
The Error Queue
The error queue is a FIFO queue (first-in first-out). That is, the first error
read is the oldest error to have occurred.I
If too many errors are put into the queue, the message '-350 <Queue
Overow>' is placed as the last message in the queue.
Some Notes about Programming and Syntax
Diagram Conventions
A program message is a message containing commands or queries that
you send to the polarization controller. The following are a few points
about program messages:
• You can use either upper-case or lower-case characters.
• You can send several commands in a single message. Each command must be
separated from the next one by a semicolon (;).
• You end a program message with a line feed (LF) character, or any character
sent with End-Or-Identify (EOI).