VNA Master™Programming Manual : Programming with SCPI : Notational Conventions
 
Notational Conventions
The SCPI interface standardizes command syntax and style to simplify the task of programming across a wide range of instrumentation. As with any programming language, the exact command keywords and command syntax must be used. Unrecognized commands or improper syntax will not function.
Notational Conventions
:


A colon links command keywords together to form commands. The colon is not an actual part of the keyword, but is a signal to the SCPI interface parser. A colon must precede a root keyword immediately following a semicolon (see Notational Examples).
;
A semicolon separates commands if multiple commands are placed on a single program line.
[ ]
Square brackets enclose one or more optional keywords.
{ }
Braces enclose one or more keyword or command parameters that may be included one or more times.
|
 
A vertical bar indicates “or” and is used to separate alternative parameter options.
Example: ON | OFF is the same as ON or OFF.
< >
Angle brackets enclose parameter descriptions.
::=
Means “is defined as”. For example: <a>::=<b><c> indicates that <b><c> can
replace <a>.
sp
Space, referred to as white space, must be used to separate keywords from their associated data parameters. It must not be used between keywords or inside keywords.
XXX
Indicates a root command name.
For further information about SCPI command syntax and style, refer to the Standard Commands for Programmable Instruments (SCPI) 1999.0 document.
 
Notational Examples
Creating Valid Commands
Command Specification
Valid Forms
[:SENSe]:FREQuency:STARt <freq>
The following all produce the same result:
:SENSe:FREQuency:STARt 1 MHZ
:SENS:FREQ:STAR 1 MHZ
:sense:frequency:start 1000000
:FREQ:STAR 1000 KHZ
:CALCulate:MARKer{1|2|3|4|5|6}:X <x‑parameter>
The first 2 commands set the location of marker 1. The third command sets the location of marker 2.
:CALC:MARK:X 1 GHZ
:CALC:MARK1:X 1 GHZ
:CALC:MARK2:X 2 GHZ
:UNIT:POWer DBM|DBV|DBMV|DBUV|V|W
The following commands are identical:
:UNIT:POWer DBM
:unit:pow dbm
:INITiate:CONTinuous OFF|ON|0|1
The following commands are identical:
:INITiate:CONTinuous OFF
:init:cont 0
Command statements read from left to right and from top to bottom. In the command statement above, the :FREQuency keyword immediately follows the :SENSe keyword with no separating space. A space (sp) is used between the command string and its argument.
Note that the first keyword in the command string does not require a leading colon. It is good practice, however, to always use a leading colon for all keywords. Note also that the [:SENSe] keyword is optional. This is a SCPI convention (for all voltage or signal source type instruments) that allows shorter command statements to be used.
The following is an example of a multiple command statement that uses two separate commands in a single statement:
:FREQuency:STARt 10E6;:FREQuency:STOP 20E9
Note 
A semicolon is used to join the commands, and a leading colon is used immediately after the semicolon to start the second command.
Command Terminators
The <new line> character (ASCII 10) in the last data byte of a command string is used as a command terminator. The use of a command terminator resets the command path to the root of the tree.