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1 Introduction to SCPI
Introduction to the SCPI Language
2 U3606A Programmer’s Reference
Introduction to the SCPI Language
SCPI, also known as the Standard Commands for Programmable
Instruments, is an ASCII- based instrument command language designed
for test and measurement instruments. SCPI commands define how you
communicate with an instrument from a bus controller.
They are based on a hierarchical structure, similar to the file systems
used by many bus controllers. This hierarchical structure is also known as
a tree system. In this system, associated commands are grouped together
under a common node or root, thus forming subsystems. You must specify
the complete path to execute the individual lower- level commands. A
portion of the
SOURce
subsystem is shown below to illustrate the tree
system.
SOURce
:VOLTage
:LIMit <value>
:LIMit?
SOURce
:CURRent
:RANGe <value>
SOURce
is the root keyword of the command,
VOLTage
and
CURRent
are
second- level keywords, and
LIMit
and
RANGe
are third- level keywords. A
colon (
:
) separates a command keyword from a lower- level keyword.
Mnemonic forms
Each keyword has both a long and a short form. A standard notation is
used to differentiate the short–form keyword from the long–form keyword.
The long form of the keyword is shown, with the short–form portion
shown in uppercase characters, and the rest of the keyword shown in
lowercase characters. For example, the short form of
SOURce is SOUR .
For shorter program lines, you can send the abbreviated form. For better
program readability, you can send the long form. For example, in the
above syntax statement,
SOURce
and
SOUR
are both acceptable forms. You
can use a mixture of upper- case and lower- case letters. Therefore,
SOURCE
,
sour
, and
Sour
are all acceptable forms. Other forms, such as
SOU
and
sourc
, are not valid and will generate an error.