Siemens NAN 67 Series Manual de Serviço descarregar pdf (Página 19)

2-3

Ladder Logic (LAD) for S7-300 and S7-400

C79000-G7076-C504-02

You can also define your own data:

S You can define shared data in data blocks. This data is accessible to the

entire user program.

S You can define static variables. These are only valid in the function block

within which they are defined. Every time an FB is called, an instance

data block is specified which includes all parameters and the static data.

In the case of multiple instances, the instance and static data are

incorporated in the instance data block.

S You can define temporary data when you create logic blocks. This data

only requires stack memory during the actual processing of the block.

Data blocks store the data of the user program. There are two types of data

blocks: shared data blocks and instance data blocks.

S Shared DBs can be accessed by all the blocks in the program.

S Instance data blocks are assigned to a function block and contain not only

the data of the function block but also the data of any defined multiple

instances. For this reason, you should only access an instance data block

in connection with its own specific function block.

The Programming Manual /234/ contains an introduction to programming

methods.

Data Blocks

Additional

Information

Introduction

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