SCL Data Types Reference

Elementary Data Types#

Note: SINT, USINT, UINT, UDINT, LREAL, WCHAR are available on S7-1200 and S7-1500 only (not on S7-300/400).

String Types#

STRING internals: A STRING[10] occupies 12 bytes in memory. The first byte stores the maximum length (10), the second byte stores the current length, followed by the character data. Strings are NOT null-terminated like C strings.

Time and Date Types#

Complex Data Types#

ARRAY#

Fixed-size collection of elements of the same type:

VAR
    #Temperatures : ARRAY[0..9] OF REAL;    // 10 REAL values
    #Names : ARRAY[1..5] OF STRING[20];     // 5 strings
    #Matrix : ARRAY[0..2, 0..2] OF INT;     // 3×3 matrix (up to 6 dimensions)
END_VAR

#Temperatures[0] := 23.5;
#Matrix[1, 2] := 42;

STRUCT#

Groups different data types together:

VAR
    #Motor : STRUCT
        Running : BOOL;
        Speed : INT;
        Current : REAL;
        Name : STRING[20];
    END_STRUCT;
END_VAR

#Motor.Running := TRUE;
#Motor.Speed := 1500;

UDT (User-Defined Type / PLC Data Type)#

Reusable type definition. Defined in "PLC data types" folder, then used in DBs and block interfaces:

// UDT definition (in PLC data types)
TYPE "Motor_Data"
    Running : BOOL;
    Speed : INT;
    Current : REAL;
END_TYPE

// Usage in a DB
VAR
    #Motor_1 : "Motor_Data";
    #Motor_2 : "Motor_Data";
END_VAR

Type Conversions#

Common conversion functions:

Part of the SCL Reference. Maintained by PLCcheck.ai.

Convert Your AWL Code to SCL#

PLCcheck Pro analyzes your S5/S7 AWL code and generates SCL equivalents automatically. Upload your program and see the conversion side by side.

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