Restrictions when reusing a CODESYS V2.3 Gateway Server project in CODESYS

Compilation	The project has to be compilable without errors in CODESYS V2.3 Gateway Server. Note: CODESYS stills issues warnings in V3 when compiling. These are caused by implicit conversions, which can lead to a loss of information (for example through sign changes). CODESYS V3 checks "case" statements against the switch variable: `‎CASE USINT OF INT‎` is not checked in CODESYS V2.3 Gateway Server, but it issues an error message when imported into V3.
Controller configuration	The “Controller Configuration” of a CODESYS V2.3 Gateway Server project cannot be imported into V3. You have to recreate the device configuration and re-declare the variables used in the controller configuration.
Network Variables	For network variables, CODESYS creates V3 GVL objects and imports the variable declarations. However, the network properties are not imported. See the description of the network variable exchange for this.
Libraries	All variables and constants that are used in a library also have to be declared in the library. It has to be possible to compile the library in CODESYS V2.3 Gateway Server without errors.
Syntactic and semantic restrictions since CODESYS V2.3 Gateway Server	`‎FUNCTIONBLOCK‎` is not a valid keyword instead of `‎FUNCTION_BLOCK‎`. `‎TYPE‎` (declaration of a structure) must be followed by a ":". `‎ARRAY‎` initialization** must have parentheses. `‎INI‎` is no longer supported (you have to replace this in the code by the Init method). In function calls it is no longer possible to mix explicit with implicit parameter assignments. Therefore the order of the parameter input assignments can be changed: `‎fun(formal1 := actual1, actual2); // -> error message‎` `‎fun(formal2 := actual2, formal1 := actual1); // same semantics as the following line:‎` `‎fun(formal1 := actual1, formal2 := actual2);‎` CODESYS V2.3 Gateway Server pragmas are not converted. They produce an warning in V3. The `‎TRUNC‎` operator now converts to the data type `‎DINT‎` instead of `‎INT‎`. CODESYS automatically adds a corresponding type conversion for a CODESYS V2.3 Gateway Server import.
Visualization
Placeholders and their replacement	Placeholders	VAR_INPUT	Usage	Replacement
	`‎PLC_PRG.$LocalVar$.aArr[0]‎`	`‎localVar: MyStruct;‎`	`‎localVar.aArr[0]‎`	`‎localVar := PLC_PRG.myStructVar‎`
	`‎$Var$.aArr[0]‎`	`‎Var : MyStruct;‎`	`‎Var.aArr[0]‎`	`‎Var := PLC_PRG.myStructVar‎`
	`‎PLC_PRG.myStructVar.aArr[$Index$]‎`	`‎Index : INT;‎`	`‎PLC_PRG.myStructVar.aArr[Index]‎`	`‎Index := 0‎`
Problematic placeholders	Placeholders within a text Text: `‎$axle$-Axis‎` Correction: `‎localVar : STRING;‎` Text: `‎%s-Axis‎` Text variable: `‎localVar‎` Placeholder describes only one part of a variable name `‎axis$axis$spur$spur$.fActPosition‎` Correction: Define only one placeholder for the `‎axis$axis$spur$spur$‎` placeholder. `‎axis_spur : MyFunctionBlock;‎` Then directly transfer the corresponding instance of the function block. `‎axis_spur := PLC_PRG.axis1spur2;‎` Placeholder is replaced by an expression `‎$Expression$ -> PLC_PRG.var1 + PLC_PRG.var2‎` Correction: You have to transfer the expression to an auxiliary variable and then transfer this auxiliary variable as an instance. Placeholder describes a program name: $Program$.bToggle - PLC_PRG.bToggle D The converter cannot transfer this form of setting placeholders in V3. However, you will rarely use it in practice. Placeholder is replaced by different types: `‎$Var$‎` -> Replacement 1 : `‎PLC_PRG.n‎` (INT) -> Replacement 2 : `‎PLC_PRG.st‎` (STRING) Correction: Define two different placeholders in the interface for this. The visualization is located in a library. You replace the placeholder later from any desired project when you use the visualization there. Correction: Here you have to replace the `‎TYPE_NONE‎` data types manually. However, there is also the possibility for you to integrate the library in a project and the placeholder is correctly replaced. If you now import this project, the data type is also determined correctly in the library.
Non-importable elements	Trend, ActiveX: Importing is not possible because the implementation differs considerably. In V3, a corresponding warning is issued and a corresponding manual reproduction is required.
Programming languages	ST, IL, FBD	No restrictions
	LD	CODESYS imports function blocks with parallel branches in such a way that the part before the branch is repeated for each branch. This corresponds to the generated code which CODESYS V2.3 Gateway Server creates for parallel branches.
	SFC	Step variables explicitly declared by the user must be declared locally in the SFC editor. You may not declare them as VAR_INPUT, VAR_OUTPUT or VAR_INOUT, because CODESYS cannot automatically adapt the calls. Explanation: Steps no longer use Boolean variables for the management of the internal states in V3, but also structures of the type `‎SFCStepType‎`. Identifier: the following identifiers may not begin with an underscore character: Names of IEC actions in the tree Variables that are called in an IEC association list Names of transitions that have been programmed out Explanation: In V3, the implicit variables which CODESYS creates for actions are given an underscore character as prefix. An invalid identifier with a double underscore character would result.
	CFC	Large boxes: The layout of large boxes can lose quality due to an import. The boxes may overlap one another too much. (Correction planned.) Macros: Macros cannot be imported. (Correction planned.)