Agilent Technologies InfiniiVision 2000 X-Series, Руководство программиста, Страница: 792 / 930

792 Agilent InfiniiVision 2000 X-Series Oscilloscopes Programmer's Guide
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More About Oscilloscope Commands
on whether or not you have included the question mark. The command
and query forms of an instruction usually have different program data.
Many queries do not use any program data.
There are three types of headers:
• "Simple Command Headers" on page 793
• "Compound Command Headers" on page 793
• "Common Command Headers" on page 793
White Space
(Separator)
White space is used to separate the instruction header from the program
data. If the instruction does not require any program data parameters, you
do not need to include any white space. White space is defined as one or
more space characters. ASCII defines a space to be character 32 (in
decimal).
Program Data
Program data are used to clarify the meaning of the command or query.
They provide necessary information, such as whether a function should be
on or off, or which waveform is to be displayed. Each instruction's syntax
definition shows the program data, as well as the values they accept.
"Program Data Syntax Rules" on page 794 describes all of the general rules
about acceptable values.
When there is more than one data parameter, they are separated by
commas(,). Spaces can be added around the commas to improve
readability.
Program
Message
Terminator
The program instructions within a data message are executed after the
program message terminator is received. The terminator may be either an
NL (New Line) character, an EOI (End- Or- Identify) asserted in the
programming interface, or a combination of the two. Asserting the EOI
sets the EOI control line low on the last byte of the data message. The NL
character is an ASCII linefeed (decimal 10).
Long Form to Short Form Truncation Rules
To get the short form of a command/keyword:
• When the command/keyword is longer than four characters, use the
first four characters of the command/keyword unless the fourth
character is a vowel; when the fourth character is a vowel, use the first
three characters of the command/keyword.
• When the command/keyword is four or fewer characters, use all of the
characters.
N O T E
New Line Terminator Functions. The NL (New Line) terminator has the same function as
an EOS (End Of String) and EOT (End Of Text) terminator.