Command Fundamentals; Common Command Format; Scpi Command Format - VXI VT1422A User Manual

Command Fundamentals

Common
Command
Format
SCPI
Command
Format
Command
Separator
Abbreviated
Commands
Chapter 7
Commands are separated into two types: IEEE-488.2 Common Commands and
SCPI Commands. The SCPI command set for the VT1422A is 1990 compatible
The IEEE-488.2 standard defines the Common commands that perform functions
like reset, self-test, status byte query, etc. Common commands are four or five
characters in length, always begin with the asterisk character (*) and may include one
or more parameters. The command keyword is separated from the first parameter by
a space character. Some examples of Common commands are:
*RST
*ESR 32
*STB?
The SCPI commands perform functions like configuring channels, setting up the
trigger system and querying instrument states or retrieving data. A subsystem
command structure is a hierarchical structure that usually consists of a top level
(or root) command, one or more lower level commands and their parameters.
The following example shows part of a typical subsystem:
MEMory
:VME
:ADDRess <A24_address>
:ADDRess?
:SIZE <mem_size>
:SIZE?
MEMory is the root command, :VME is the second level command and :ADDRess and
SIZE are third level commands.
A colon (:) always separates one command from the next lower level command as
shown below:
ROUTE:SEQUENCE:DEFINE?
Colons separate the root command from the second level command
(ROUTE:SEQUENCE) and the second level from the third level
(SEQUENCE:DEFINE?). If parameters are present, the first is separated from the
command by a space character. Additional parameters are separated from each other
by a commas.
The command syntax shows most commands as a mixture of upper and lower case
letters. The upper case letters indicate the abbreviated spelling for the command.
For shorter program lines, send the abbreviated form. For better program readability,
send the entire command. The instrument will accept either the abbreviated form or
the entire command.
For example, if the command syntax shows SEQuence, then SEQ and SEQUENCE
are both acceptable forms. Other forms of SEQuence, such as SEQUEN or SEQU
will generate an error. Upper or lower case letters can be used. Therefore,
SEQUENCE, sequence, and SeQuEnCe are all acceptable.
VT1422A Command Reference 229