Agilent Technologies 6811B, 6834B, 6814B Query Indicator, Message Unit Separator, Root Specifier

2 - Introduction to Programming

Header In the command descriptions in Chapter 3 of this manual, headers are emphasized with Convention boldface type. The proper short form is shown in upper-case letters, such as DELay.

Header If a command has more than one header, you must separate them with a colon

Separator (VOLT:PROT OUTPut:RELay:POLarity).

Optional The use of some headers is optional. Optional headers are shown in brackets, such as

Headers OUTPut[:STATe] ON. As previously explained under "The Effect of Optional Headers", if you combine two or more message units into a compound message, you may need to enter the optional header.

Query Indicator

Following a header with a question mark turns it into a query (VOLTage?, VOLTage:PROTection?). If a query contains a parameter, place the query indicator at the end of the last header (VOLTage:PROTection? MAX).

Message Unit Separator

When two or more message units are combined into a compound message, separate the units with a semicolon (STATus:OPERation?;QUEStionable?).

Root Specifier

When it precedes the first header of a message unit, the colon becomes the root specifier. It tells the command parser that this is the root or the top node of the command tree. Note the difference between root specifiers and header separators in the following examples:

OUTPut:PROTection:DELay .1 :OUTPut:PROTection:DELay .1 OUTPut:PROTection:DELay .1;:VOLTage 12.5

All colons are header separators Only the first colon is a root specifier Only the third colon is a root specifier

NOTE: You do not have to precede root-level commands with a colon; there is an implied colon in front of every root-level command.

Message Terminator

A terminator informs SCPI that it has reached the end of a message. Three permitted messages terminators are:

υnewline (<NL>), which is ASCII decimal 10 or hex 0A.

υend or identify (<END>)

υboth of the above (<NL><END>).

In the examples of this guide, there is an assumed message terminator at the end of each message. If the terminator needs to be shown, it is indicated as <NL> regardless of the actual terminator character.

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