TIA-SCL

Siemens SCL (Structured Control Language) support for Visual Studio Code.

Features

Syntax Highlighting

Full highlighting for .scl files:

• Keywords - FUNCTION_BLOCK, IF/THEN, FOR/DO, CASE/OF, etc.
• Data types - Bool, Int, Real, Time, String, Array, Struct, IEC timers/counters
• Variables - #local variables, "DB_Name" references, %I/%Q/%M addresses
• Literals - Time (T#5s), hex (16#FF00), binary (2#1010), dates (D#2024-01-15)
• System functions - Type conversions, math, string functions, S7 system calls
• Comments - // line and (* block *) comments
• Pragmas - { S7_Optimized_Access := 'TRUE' }

Code Snippets

Type a prefix and press Tab to insert:

Prefix	Snippet
fb	Function Block (full template)
fc	Function with return type
ob	Organization Block
db	Data Block
idb	Instance Data Block
udt	User Defined Type (STRUCT)
if	IF THEN END_IF
ife	IF THEN ELSE END_IF
ifei	IF ELSIF ELSE END_IF
for	FOR loop
while	WHILE loop
repeat	REPEAT UNTIL loop
case	CASE OF statement
var_input	VAR_INPUT section
var_output	VAR_OUTPUT section
var_inout	VAR_IN_OUT section
var_temp	VAR_TEMP section
ton	TON timer call
tof	TOF timer call
tp	TP pulse timer call
ctu	CTU counter call
rtrig	R_TRIG rising edge
ftrig	F_TRIG falling edge
call	FB instance call
norm	NORM_X normalize
scale	SCALE_X scale
motor	Motor control pattern
statemachine	State machine (CASE)
analogscale	Analog scaling formula
region	REGION fold block

IntelliSense / Autocomplete

Real-time autocomplete as you type:

• Keywords - All SCL block, variable and control flow keywords with documentation
• Data types - All S7 data types with size info (suggested automatically after :)
• System functions - Type conversions, math, string, scaling functions with parameter info
• # variables - Type # to see all declared variables in the current block
• % addresses - Type % to get I/Q/M address suggestions
• " block references - Type " to see all block names in the file
• . member access - Timer/Counter outputs (Q, ET, CV) after dot

Hover Documentation

Hover over any keyword, data type or system function to see documentation.

Signature Help

Parameter hints when calling system functions - shows parameter names and types as you type.

Linter / Diagnostics

Real-time error checking as you type:

Errors (red):

Code	Check
SCL001	Unmatched control flow (IF without END_IF, FOR without END_FOR, ...)
SCL002	Unmatched VAR sections (VAR_INPUT without END_VAR)
SCL003	Unmatched block declarations (FUNCTION_BLOCK without END_FUNCTION_BLOCK)
SCL004	Duplicate variable names in same block
SCL005	EXIT/CONTINUE outside of a loop

Warnings (yellow):

Code	Check
SCL101	Unused variables (declared but never referenced)
SCL102	Missing VERSION declaration
SCL103	Missing S7_Optimized_Access pragma
SCL104	CASE statement without ELSE branch
SCL105	Empty BEGIN section (no code)

Hints (grey):

Code	Check
SCL201	Naming convention (FB_, FC_, DB_ prefix suggestion)

Symbol Outline / Breadcrumbs

Full document outline in the Explorer panel and breadcrumb navigation:

• Blocks - FUNCTION_BLOCK, FUNCTION, ORGANIZATION_BLOCK, DATA_BLOCK, TYPE
• VAR sections - VAR_INPUT, VAR_OUTPUT, VAR_IN_OUT, VAR_TEMP, VAR as nested children
• Variables - All declared variables grouped under their section
• Correct SymbolKind mapping (FB=Class, FC=Function, OB=Event, DB=Struct)

Go to Definition

Ctrl+Click or F12 to navigate:

• #Variable - Jump to variable declaration in VAR section
• "BlockName" - Jump to block declaration (FUNCTION_BLOCK, FUNCTION, etc.)
• Plain identifiers - Fallback match against all declared variables (case-insensitive)

Code Formatting

Shift+Alt+F to format SCL code:

• Indentation - 4 spaces per nesting level, correct for all block/control structures
• Keyword casing - All SCL keywords converted to UPPERCASE
• Spacing - Consistent spacing around :=, :, ,
• Preserves - Strings, comments, and pragmas are never modified
• CASE labels - Correct indentation for numeric case labels

Quick Fixes

Ctrl+. on linter warnings to auto-fix:

Code	Quick Fix
SCL102	Add VERSION : 0.1 declaration
SCL103	Add { S7_Optimized_Access := 'TRUE' } pragma
SCL104	Add ELSE branch to CASE statement
SCL201	Rename block with FB_/FC_/DB_ prefix

Code Folding

Automatic folding for:

• Block declarations (FUNCTION_BLOCK, FUNCTION, etc.)
• Variable sections (VAR_INPUT, VAR_OUTPUT, etc.)
• Control structures (IF, FOR, WHILE, CASE)
• Regions (REGION / END_REGION)

Auto-Indentation

Automatic indent/outdent for block keywords and control flow.

Bracket Matching

Matching of parentheses, brackets, and (* *) comments.

Installation

From VS Code Marketplace

Search for TIA-SCL in the Extensions view (Ctrl+Shift+X).

From VSIX File

Download the .vsix from Releases, then:

code --install-extension tia-scl-0.4.0.vsix

Or in VS Code: Ctrl+Shift+P → Extensions: Install from VSIX...

Manual Installation

git clone https://github.com/kasi09/TIA-SCL.git
cd TIA-SCL
npm install && npm run build
# Copy to extensions folder (Windows):
cp -r . "%USERPROFILE%/.vscode/extensions/tia-scl"
# Restart VS Code

File Association

The extension automatically associates with .scl files. To manually set the language mode, click the language indicator in the bottom right of VS Code and select SCL.

Related

• TIA-Tools - Python toolkit for Siemens TIA Portal projects (reader, block generator, SCL generator, tag export)

License

MIT