Structure And Syntax Of The Device Messages; Scpi Introduction; Structure Of A Command - Rohde & Schwarz R&S FSP Series Operating Manual

R&S FSP
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– Device responses are messages the instrument sends to the controller after a
query. They can contain measurement results, instrument settings and
information on the instrument status (cf. section
page
Structure and syntax of the device messages are described in the following section.

5.6 Structure and Syntax of the Device Messages

5.6.1

SCPI Introduction

SCPI (Standard Commands for Programmable Instruments) describes a standard
command set for programming instruments, irrespective of the type of instrument or
manufacturer. The goal of the SCPI consortium is to standardize the device-specific
commands to a large extent. For this purpose, a model was developed which
defines the same functions inside a device or for different devices. Command sys-
tems were generated which are assigned to these functions. Thus it is possible to
address the same functions with identical commands. The command systems are of
a hierarchical structure.
Fig. 5.1
which controls the device-specific settings, that do not refer to the signal character-
istics of the measurement signal. Further examples of structure and syntax are
taken from this command system.
SCPI is based on standard IEEE 488.2, i.e. it uses the same syntactic basic ele-
ments as well as the common commands defined in this standard. Part of the syntax
of the device responses is defined with greater restrictions than in standard IEEE
488.2 (see section
5.6.2

Structure of a Command

The commands consist of a so-called header and, in most cases, one or more
parameters. Header and parameter are separated by a "white space" (ASCII code 0
to 9, 11 to 32 decimal, e.g. blank). The headers may consist of several key words.
Queries are formed by directly appending a question mark to the header.
Operating Manual 1164.4556.12 - 06
According to the effect they have on the instrument:
Setting commands cause instrument settings such as reset of the instrument
or setting the center frequency.
Queries cause data to be provided for output on the GPIB, e.g. for
identification of the device or polling the marker.
According to their definition in standard IEEE 488.2:
Common Commands are exactly defined as to their function and notation in
standard IEEE 488.2. They refer to functions such as management of the
standardized status registers, reset and selftest.
Device-specific commands refer to functions depending on the features of
the instrument such as frequency setting. A majority of these commands has
also been standardized by the SCPI committee (cf. section
on page 5.9).
5.13).
illustrates this tree structure using a section of command system SENSe,
"Responses to Queries" on page
Remote Control – Basics
Structure and Syntax of the Device Messages
"Responses to Queries" on
5.13).
"SCPI Introduction"
5.9