HP 1650B, Руководство программиста, Страница: 295 / 346

Syntax
Diagrams
The syntax diagrams in this appendix are similar to the syntax diagrams in
the IEEE 488.2 specification. Commands and queries are sent to the
instrument as a sequence of data bytes. The allowable byte sequence for
each functional element is defined by the syntax diagram that is shown
with the element description.
The allowable byte sequence can be determined by following a path in the
syntax diagram. The proper path through the syntax diagram is any path
that follows the direction of the arrows. If there is a path around an
element, that element is optional. If there is a path from right to left
around one or more elements, that element or those elements may be
repeated as many times as desired.
Syntax
Overview
This overview is intended to give a quick glance at the syntax defmed by
IEEE 488.2. It should allow you to understand many of the things about
the syntax you need to know. This appendix also contains the details of
the IEEE 488.2 defined syntax.
IEEE 488.2 defines the blocks used to build messages which are sent to
the instrument. A whole string of commands can therefore be broken up
into individual components.
A-l shows a breakdown of an example program message .
There are a few key items to notice:
1. A semicolon separates commands from one another. Each c program
message unit serves as a container for one command. The
program message unit are separated by a semicolon.
2. A program message is terminated by a NL (new line).
The
recognition of the program message terminator , or PMT , by
the parser serves as a signal for the parser to begin execution of
commands. The PMT also affects command tree traversal (see
the Programming and Documentation Conventions chapter).
3. Multiple data parameters are separated by a comma.
4. The first data parameter is separated from the header with one or more
spaces.
HP 1651B Message Communication and System Functions
Programming Reference A-5