Introduction

The DDT (Derived Data Type) family includes "derived" data types such as:

  • tables

  • structures

Illustration:

Characteristics

A data item belonging to the DDT family is made up of:

  • the type name (32 characters maximum) defined by the user (not obligatory for tables but recommended)

  • the type (structure or table)

  • an optional comment (of a maximum of 1024 characters). Authorized characters correspond to the ASCII codes 32 to 255

  • the description (in the case of a structure) of these elements

    • the element type

    • an optional comment (1024 characters maximum) describing its role. The authorized characters correspond to the ASCII codes 32 to 255

  • information such as:

    • type version number

    • date of the last modification of the code or of the internal variables or of the interface variables

    • an optional descriptive file (32767 characters) describing the block function and its different modifications

NOTE:

  1. M580 Platform and PLC Simulator: the total size of a table does not exceed 2 Mbytes for DDT structures and DDT arrays

  2. Other Platforms: the total size of a table does not exceed 64 Kbytes

Examples

Definition of types

Access to the data of a DRAW-type structure instance