Agilent Technologies N3280A manual Introduction to Scpi, Types of Scpi Commands

4 - Introduction to Programming

Introduction to SCPI

SCPI (Standard Commands for Programmable Instruments) is a programming language for controlling instrument functions over the GPIB. 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, <NR1>
				indicates a specific form of numerical data.
Vertical bar				Vertical bars separate alternative parameters. For example, VOLT CURR
				indicates that either "VOLT" or "CURR" 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 <A>{<,B>} shows that parameter "A"
				must be entered, while parameter "B" may be omitted or may be entered one or
				more times.
Parentheses	(	)		Items within parentheses are used in place of the usual parameter types to specify a
				channel list. The notation (@1:3) specifies a channel list that includes channels 1,
				2, and 3. The notation (@1,3) specifies a channel list that includes only channels 1
				and 3.
Computer font				Computer font is used to show program lines in text.
				TRIGger:ACQuire:SOURce BUS shows a program line.

Types of SCPI Commands

SCPI has two types of commands, common and subsystem.

♦Common commands generally are not related to specific operation but to controlling overall dc

source functions, such as reset, status, and synchronization. All common commands consist of a three-letter mnemonic preceded by an asterisk: *RST *IDN? *SRE 8

♦Subsystem commands perform specific dc source 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. You can see the complete tree in Appendix. D.

ROOT
	:OUTPut	[:STATe]	[:STATe]
		:OSCProtect
		:PROTection	:CLEar
	:STATus	:OPERation	[:EVEN]?
			:CONDition?

Figure 4-1. Partial Command Tree

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