Procedure For Programming Blocks - Siemens SIMATIC S7-300 Quick Start Manual

Programming Logic Blocks with STEP 7

Procedure for Programming Blocks

Introduction
You can program your programmable controller quite easily by creating a
user program that you download to the CPU of your S7-300. The user
program you have to create consists of different blocks which enable you to
structure your program. For the TLIGHT sample program, you require only
two blocks:
What is an
An organization block (OB) is the interface between the operating system of
Organization Block
the CPU and your user program. The order in which the user program is
(OB)? executed is defined in an OB.
What is a Function A function (FC) is a logic block without 'memory' which can nevertheless
(FC)?
transfer parameters. This block is especially suitable for programming
frequently recurring functions.
Basic Procedure
Using the TLIGHT sample program, we aim to show you the basic procedure
for programming blocks. Figure 6-1 gives you a task-oriented overview:
Figure 6-1 Basic Procedure for Programming
6-2
An organization block (OB1) for cyclic program execution and
A function (FC1) into which you enter the actual program.
Procedure for programming blocks
Create blocks:
Create FC1 and assign language editor (STL, LAD, or
FBD)
Program blocks (in STL, LAD, or FBD):
Start language editor, declare variables and enter
program, divided into networks.
Save and download blocks:
Save the blocks in your programming device/PC and
download them to the CPU
Primer: S7-300 Programmable Controller, Quick Start
C79000-G7076-C500-01