Rockwell-automation 1771-DB Basic Module User Manual - Series A Manual de usuario descargar pdf (Pagina 38)

Chapter 5

Operating Functions

After reading this chapter you should be familiar with the BASIC

instruction set and be ready to begin BASIC programming. This chapter

is a reference section to help you with module programming. You

should already be familiar with BASIC programming.

The following sections define the following terms: commands, statements,

format statements, data format, integers, constants, operators,

variables, expressions, relational expressions, system control values,

argument stack and control stack.

The BASIC module operates in two modes, the command or direct

mode and the interpreter or run mode. You can only enter commands

when the processor is in the command or direct mode. This document

uses the terms run mode and command mode to refer to the two

different operation modes.

A BASIC program consists of statements. Every statement begins with

a line number, followed by a statement body, and terminated with a

carriage return (cr), or a colon (:) in the case of multiple statements per

line. There are three types of statements: assignments, input/output and

control.

Every line in a program must have a statement line number ranging

between 0 and 65535 inclusive. BASIC uses this to order the

program statements in sequence.

You can use a statement number only once in a program.

BASIC automatically orders statements in ascending order.

A statement may not contain more than 79 characters.

BASIC ignores blanks (spaces) and automatically inserts them during

a LIST command.

5.1

Chapter

Objectives

5.2

Definition of Terms

5.2.1

Commands

5.2.2

Statements

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Rockwell-automation 1771-DB Basic Module User Manual - Series A Manual de usuario Pagina 38