292 Chapter 5
Programming Fundamentals
SCPI Language Basics
Programming Fundamentals
Parameters in Commands
There are four basic types of parameters: booleans, keywords, variables
and arbitrary block program data.
OFF|ON|0|1
(Boolean) This is a two state boolean-type parameter. The
numeric value 0 is equivalent to OFF. Any numeric
value other than 0 is equivalent to ON. The numeric
values of 0 or 1 are commonly used in the command
instead of OFF or ON. Queries of the parameter always
return a numeric value of 0 or 1.
keyword The keywords that are allowed for a particular
command are defined in the command syntax
description.
Units Numeric variables may include units. The valid units
for a command depend on the variable type being used.
See the following variable descriptions. The indicated
default units will be used if no units are sent. Units can
follow the numerical value with, or without, a space.
Variable A variable can be entered in exponential format as well
as standard numeric format. The appropriate range of
the variable and its optional units are defined in the
command description.
The following keywords may also be used in commands,
but not all commands allow keyword variables.
• DEFault - resets the parameter to its default value.
• UP - increments the parameter.
• DOWN - decrements the parameter.
• MINimum - sets the parameter to the smallest
possible value.
• MAXimum - sets the parameter to the largest
possible value.
The numeric value for the function’s MINimum,
MAXimum, or DEFault can be queried by adding the
keyword to the command in its query form. The
keyword must be entered following the question mark.
Example query: SENSE:FREQ:CENTER? MAX
Variable Parameters
<freq>
<bandwidth> Is a positive rational number followed by optional units.
The default unit is Hz. Acceptable units include: HZ,
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