Order of Prefixes

Overview

Designators contain the scope prefix and the type prefix. Use the property prefix according to the property of the variables (for example, for constants). An additional namespace prefix is used for libraries.

Obligatory Order

The following order is obligatory:

scope][property][_][type][identifier]

Scope prefixes and property prefixes are separated from type prefixes by an underscore (_).

Example

Gc_dwErrorCode   : DWORD;
diCycleCounter   : DINT;

The additional namespace prefix is used for libraries:

[namespace].[scope][property][_][type][identifier]

Example

ExampleLibrary.Gc_dwErrorCode

Independent Program Organization Units (POUs)

Insert an underscore to separate program organization units (functions, function blocks, and programs) prefixes from identifiers:

[POU][_][identifier]

Example

FB_MotionCorrection

Use the additional namespace prefix for libraries:

[namespace].[POU][_][identifier]

Namespace prefixes are separated from POU prefixes by a dot (.).

Example

ExampleLibrary.FC_SetError()

Dependent Program Organization Units (POUs)

Methods, actions, and properties are considered to be dependent POUs. These are used on a level below an independent POU.

Methods and actions do not have any prefixes.

Properties receive the type prefix of their return value.

Example

PROPERTY lrVelocity : LREAL