Siemens v1.0 Service Manual download pdf (Page 37)

Simple example

2.4 Create program

STEP 7 Basic V10.5

Getting Started, 12/2009, A5E02651459-01

2.4.5 Inserting LAD instructions

Introduction

The following steps show you how to create the program for switching on and off the

example machine in the first network of the organization block "Main [OB1]". To do this,

insert a branch and the following instructions:

● Normally open contact

● Output coil

● Negated coil

In addition you use a branch to program a parallel connection in the "LAD" programming

language.

Normally open contact

The following figure shows the icon of the normally open contact in the program:

---| |---

The activation of the normally open contact depends on the signal state of the associated tag

(<operand>).

● If the tag has signal state "1", the normally open contact is closed. Power flows from the

left power rail through the normally open contact into the right power rail and the signal

state at the output of the instruction is set to "1".

● If the tag has signal state "0", the normally open contact is not activated. The power flow

to the right power rail is interrupted and the signal state at the output of the instruction is

reset to "0".

In the course of this project you will also use a normally closed contact (Page 95) which

essentiall

y has the sa

me function as the normally open contact, but responds to the signal

state of the tag in the opposite way.

Output coil

The following figure shows the icon of the "Output coil" instruction in the program:

---( )---

You can use the "Output coil" operation to set the bit of a specified tag (<operand>). If the

signal state is "1" at the coil input, the tag bit is set to "1". If the signal state is "0" at the coil

input, the tag bit also supplies the signal state "0".

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Siemens v1.0 Service Manual Page 37