Chapter 8

Jump and Call

Abstract

This chapter considers the programming jump instruction and the way in which subroutines can be called up. Programs involving such operations are developed.

Keywords

jump instruction

sub-routines

This chapter considers the jump instruction, which enables part of a program to be jumped over, and the way in which subroutines in ladder programs can be called up. Subroutines enable commonly occurring operations in a program to be repeatedly called up and used over again.

8.1 Jump

A function often provided with PLCs is the conditional jump. We can describe this as:

IF (some condition occurs) THEN
 perform some instructions
ELSE
 perform some other instructions

Such a facility enables programs to be designed ...

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