Program And Response Messages - HP 83751A Programming Manual

Program and Response Messages

To understand how your instrument and controller communicate using
SCPI, you must understand the concepts of program and response messages.
instrument. Conversely, response messages are the formatted data sent from
the instrument to the controller. Program messages contain one or more
commands, and response messages contain one or more responses.
The controller may send commands at any time, but the instrument sends
responses only when specifically instructed to do so. The special type of
command used to instruct the instrument to send a response message is the
measured values or internal instrument settings. Any internal setting that can
be programmed with SCPI can also be queried.,
Forgiving listening and
SCPI uses the concept of forgiving listening and precise talking outlined in
Precise Talking IEEE 488.2.
various command and parameter formats. For example, the sweeper accepts
either :POWer:STATe ON or :POWer:STATe ItoturnRFoutputon.
always the same. For example, if you query the power state when it is on
(using :POWer: STATe?), the response is always I, regardless of whether you
previously sent : POWer : STATe 1 or :POWer : STATe ON.
subsystem commands.
used to manage macros, status registers, synchronization, and data storage.
Common commands are easy to recognize because they all begin with an
asterisk, such as *IDN?, *OPC, and *RST. Common commands are defined by
IEEE 488.2.
purpose functions. Subsystem commands are distinguished by the colon used
between keywords, asin :FREQuency:CW.. 3 Each command subsystem is a
Getting Started Programming
Essentials for Beginners
1-19