Differences compared with TwinCAT 2

Library versions

• Several versions of a library are possible in the same project. Unambiguous accesses are ensured by specifying the namespace.
• Installation in repositories (databases with libraries in various versions)
• Automatic updating
• Debugging possible
• Library profiles and placeholders facilitate version compatibility

Compatibility with projects in other file formats

• The command Add Existing Item … can be used to automatically convert projects with different formats to the TwinCAT 3 format. You can define how integrated libraries should be handled.
• A converter for the TwinCAT 2 format is part of the standard programming system. However, if you want to use a TwinCAT 2 project in TwinCAT 3, you have to take into account some prerequisites and restrictions.

Data types

The following data types are new:

• any_type
• UNION
• LTIME
• BIT
• References
• Enumerations: Base data type can be specified.
• di : DINT := DINT#16#FFFFFFFF : not permitted

Editors

ST editor:

• Bracketing, breaks, code completion, inline monitoring, inline set/reset assignment

FBD/LD/IL editor:

• FBD, LD and IL can be converted to each other and have a common editor.
• IL editor as table editor
• The main output in function blocks with multiple outputs can be set.
• Branches and “networks in networks”

SFC editor:

• Only one step type, macros, multiple selection of independent elements, no syntax check during editing

Visualization concept

• By default, the visualization editor cooperates with a toolbox and an editor for the element properties.
• Parts of the visualization functionality are implemented in accordance with IEC 61131 and are therefore made available through libraries. An internal runtime system performs the main visualization functions.
• Text lists and image pools are used for managing texts and image files.
• A visualization manager deals with different visualization clients (such as web client, standalone client...), which can be used flexibly and with little effort for a wide range of custom PLC projects.
• Visualization profiles define which library versions and which elements are currently available.
• Visualization styles facilitate adaptation of the “look and feel” of the visualizations.

Operators and variables

• New validity range operators, extended namespaces
• Init method replaces the INI operator
• Exit method
• Output variables in function and method calls
• VAR_TEMP, VAR_STAT
• Any expressions for variable initialization
• Assignment as expression
• Index access with pointers and strings

Object orientation

• Extensions for function blocks: properties, interfaces, methods, inheritance, method call

Further parameters

• Configurable menus, toolbar and keyboard operation
• Unicode support
• Single-line comments: // Comment
• CONTINUE in loops
• Conditional compilation
• Conditional breakpoints
• Debug: Run To Cursor, Step Out

Changes from TwinCAT 2 PLC:

• FUNCTIONBLOCK is no longer a valid keyword for function blocks, in place of FUNCTION_BLOCK
• TYPE (declaration of a structure) must be followed by a “:”.
• ARRAY initialization must be enclosed in parentheses.
• INI is no longer supported and must be replaced by the Init method.
• In function calls, it is no longer possible to mix explicit parameter assignments with implicit assignments. The order of the parameter input assignments can therefore be changed:

fun(formal1 := actual1, actual2); // → Fehlermeldung

fun(formal2 := actual2, formal1 := actual1); // gleiche Semantik wie ...

fun(formal1 := actual1, formal2 := actual2);

• Pragmas (import of TwinCAT 2 pragmas is not yet implemented)
• The TRUNC operator now converts to the data type DINT instead of INT; during a TwinCAT 2 import, a corresponding type conversion is added automatically.
• Direct addressing of allocated variables:

The direct addressing of allocated variables has changed. Whereas the starting point was always the same with TwinCAT 2 irrespective of the data type, a distinction is made with TwinCAT 3:

TwinCAT 2: W0 contains B0 and B1, W1 contains B1 and B2, W100 contains B100 and B101

TwinCAT 3: W0 contains B0 and B1, W1 contains B2 and B3, W100 contains B200 and B201