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Programming Basics

The most important ingredients in creating a successful PLC program are a thorough understanding of the application itself, and a good measure of common sense.

The first step in creating a PLC application program is planning.

hThe desired sequence of program actions is determined.

hAll of the required inputs and outputs are identified and listed.

hEach input and output is associated with a PLC memory location. For example:

Device

Designation

Memor y Location

 

 

 

 

Start switch

Input 1

Discrete Input Table

1

Limit switch on conveyor line

Input 2

º

2

Syrup tank #1, level detector

Input 3

º

3

Syrup tank #2, level detector

Input 4

º

4

Conveyor line optical sensor

Input 5

º

5

 

 

 

Conveyor line motor starter

Output 1

Discrete Output Table1

Operator warning light

Output 2

º

2

Signal to bottle capper

Output 3

º

3

 

 

 

 

hThe program (like the short example program on the facing page) is created with a programming device and transferred to the PLC.

hBefore the system begins full operation, the program is tested and any corrections that are needed are made.

hThe final version of the program is transferred to the PLC, and the application is ready to go.

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Micro PLC Programmer's Guide ± April 1994

GFK-0804B

Page 10
Image 10
GE GFK-0804B manual Programming Basics, Device Designation