Overview of Data Instances

Introduction

A data instance is an individual functional entity, which has all the characteristics of the data type to which it belongs.

One or more instances can belong to a data type.

The data instance can have a memory allocation that is:

unlocated or
located

Illustration

Definitions

Definition of the memory allocations of data instances.

Data instance	Definition
Unlocated	The memory slot of the instance is automatically allocated by the system and can change for each generation of the application. The instance is located by a name (symbol) chosen by the user.
Located	The memory slot of the instance is fixed, predefined and never changes. The instance is located by a name (symbol) chosen by the user and a topological address defined by the manufacturer, or by the topological address of the manufacturer only.

Data instance

Definition

Unlocated

The memory slot of the instance is automatically allocated by the system and can change for each generation of the application.

The instance is located by a name (symbol) chosen by the user.

Located

The memory slot of the instance is fixed, predefined and never changes.

The instance is located by a name (symbol) chosen by the user and a topological address defined by the manufacturer, or by the topological address of the manufacturer only.