B&K Precision MDL Series - Programming Manual - Manual (Page 18)

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Chapter 2
Introduction to SCPI
SCPI (Standard Commands for Programmable Instruments) is a programming language for controlling
instrument functions over GPIB, RS-232, USB, and Ethernet interface. SCPI is layered on top of the
hardware portion of IEEE 488.2. The same SCPI commands and parameters control the same functions
in different classes of instruments.
Conventions Used in This Guide
Angle brackets < > Items within angle brackets are parameter abbreviations. For example,
indicates a specific form of numerical data.
Vertical bar | Vertical bars separate alternative parameters. For example, NORM | TEXT
indicates that either "NORM" or "TEXT" can be used as a parameter.
Square Brackets [ ]
Items within square brackets are optional. The representation [SOURce:]
VOLTage means that SOURce: may be omitted.
Braces
{ } Braces indicate parameters that may be repeated zero or more times. It is
used especially for showing arrays. The notation {<,B>} shows that
parameter "A" must be entered, while parameter "B" may be omitted or may
be entered one or more times.
2.1 Types of SCPI Commands
SCPI has two types of commands, common and subsystem.
Common:
Common commands generally are not related to specific operation but to controlling overall
electronic load functions, such as reset, status, and synchronization. All common commands
consist of a three-letter mnemonic preceded by an asterisk (ex:*RST, *IDN?, *SRE 8).
Subsystem:
Subsystem commands perform specific electronic load 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.