14 Sequoia Series
2. Introduction to SCPI
SCPI (Standard Commands for Programmable Instruments) is a programming language for controlling
instrument functions over the IEEE-488. SCPI is layered on top of the hardware-portion of IEEE 488.1.
The same SCPI commands and parameters control the same functions in different classes of
instruments. For example, you would use the same MEAS:VOLT? command to measure the power
source output voltage or the output voltage measured using an SCPI-compatible multimeter.
2.1 Conventions Used in This Manual
Angle brackets<> Items within angle brackets are parameter abbreviations. For
example, <NR1> indicates a specific form of numerical data.
Vertical bar Vertical bars separate alternative parameters. For example, FIX |
STEP indicates that either "FIX" or "STEP" can be used as a
parameter.
Square Brackets [ ] Items within square brackets are optional. The representation
[SOURce:]LIST 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 <A>
<,B> shows that parameter "A" must be entered, while parameter
"B" may be omitted or may be entered one or more times.
Boldface font Boldface font is used to emphasize syntax in command definitions.
TRIGger:SOURCe<NRf> shows a command definition.
Computer font Computer font is used to show program lines in text.
TRIGger:SOURCe INT
shows a program line.
2.2 The SCPI Commands and Messages
This paragraph explains the syntax difference between SCPI Commands and SCPI messages.
2.2.1 Types of SCPI Commands
SCPI has two types of commands, common and subsystem.
• Common commands are generally not related to specific operations but to controlling
overall power source functions such as reset, status, and synchronization. All common
commands consist of a three-letter mnemonic preceded by an asterisk:
*RST
*IDN?
*SRE 256
• Subsystem commands perform specific power source functions. They are organized into
an inverted tree structure with the "root" at the top. Some are single commands while
others are grouped within specific subsystems.
Refer to appendix A for the power source SCPI tree structure.
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