CODESYS CONCAT

CONCAT is a function in the CODESYS Standard library that joins two strings into one. It takes two STRING(255) inputs, STR1 and STR2, and returns a single STRING(255) containing STR1 immediately followed by STR2. In the documented example, CONCAT('SUSI','WILLI') returns 'SUSIWILLI'.

Source checked9/9 values · 2026-10-26

Specification

2 sources

Language	structured text
Code	CONCAT
Group	String Functions
Syntax	CONCAT(STR1, STR2)
Dialect	CODESYS

Parameters

Name	Data type	Description
STR1	STRING(255)	String 1 to be concatenated, max. 255 characters.
STR2	STRING(255)	String 2 to be concatenated, max. 255 characters.

Study notes

Declared as FUNCTION CONCAT : STRING(255).
Return value is limited to 255 characters; if the result does not fit into 255 bytes it is silently truncated and no error is produced.
Both inputs STR1 and STR2 are of type STRING(255).
Example in ST: VarSTRING1 := CONCAT('SUSI','WILLI'); gives the result 'SUSIWILLI'.
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