Agilent Technologies 6813B Combining Message Units, Headers, 2.Command Message Structure, Example

Introduction to Programming - 2

Combining Message Units

The following command message is briefly described here, with details in subsequent paragraphs.

Data

Message Unit

Headers

Query Indicator

VOLT:LEV 80 ;	PROT 88 ; : CURR? <NL>
Header Separator	Message Terminator
Message Unit Separators
	Root Specifier

Figure 2-2. Command Message Structure

The basic parts of the above message are:

Message Component	Example
Headers	VOLT LEV	PROT CURR
Header Separator	The colon in VOLT:LEV
Data	8088
Data Separator	The space in VOLT 80 and PROT 88
Message Units	VOLT:LEV 80	PROT 88 CURR?
Message Unit Separator	The semicolons in VOLT:LEV 80; and PROT 88;
Root Specifier	The colon in PROT 88;:CURR?
Query Indicator	The question mark in CURR?
Message Terminator	The <NL> (newline) indicator. Terminators are not part of the SCPI syntax

Headers

Headers are instructions recognized by the ac source. Headers (which are sometimes known as "keywords") may be either in the long form or the short form.

Long Form The header is completely spelled out, such as VOLTAGE, STATUS, and DELAY.

Short Form The header has only the first three or four letters, such as VOLT, STAT, and DEL.

The SCPI interface is not sensitive to case. It will recognize any case mixture, such as TRIGGER, Trigger, TRIGger.

NOTE: Short form headers result in faster program execution.

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