SCPI Introduction
Copyright © ITECH Electronic Co., Ltd. 1
Chapter1 SCPI Introduction
1.1 Overview
SCPI is short for Standard Commands for Programmable Instruments which
defines a communication method of bus controller and instrument. It is based on
ASCII and supply for testing and measuring instruments. SCPI command is
based on hierarchical architecture which also known as tree system. In this
system, Relevant Command is returned to a common node or root, so that a
subsystem is formed. A part of OUTPut subsystem is listed below:
1.2 Command Type of SCPI
SCPI has two types of commands, common and subsystem.
⚫ Common commands generally are not related to specific operation but to
controlling overall instrument functions, such as reset, status, and
synchronization. All commoncommands consist of a three-letter mnemonic
preceded by an asterisk: *RST *IDN? *SRE 8.
⚫ Subsystem commands perform specific instrument functions. They are
organized into an inverted tree structure with the "root" at the top. The
following figure shows a portion of a subsystem command tree, from which
you access the commands located along the various paths.
Multiple Commands in a Message
Multiple SCPI commands can be combined and sent as a single message
with one message terminator. There are two important considerations
when sending several commands within a single message:
⚫ Use a semicolon to separate commands within a message.
⚫ Head paths influence how the instrument interprets commands.
We consider the head path as a string which will be inserted in front of
every command of a message. As for the first command of a message, the
head path is a null string; for each subsequent command, the head path is
a string which is defined to form the current command until and including
the head of the last colon separator. A message with two combined
commands:
CURR:LEV 3;PROT:STAT OFF
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