CODESYS TON

TON is a function block that implements an on-delay timer. A rising edge on IN starts the delay counter, and Q becomes TRUE after the delay time PT has elapsed while IN remains TRUE. A falling edge on IN resets the delay counter.

Source checked15/15 values · 2026-10-26

Specification

2 sources

Language	structured text
Code	TON
Group	Timer
Syntax	TONInst(IN := VarBOOL1, PT := T#5s);
Dialect	CODESYS

Parameters

Name	Data type	Description
IN	BOOL	Rising edge starts delay counter. Falling edge resets delay counter.
PT	TIME	Time for the delay counter [ms].
Q	BOOL	FALSE if IN is FALSE; TRUE if IN is TRUE and delay time PT elapsed.
ET	TIME	Elapsed time since rising edge at IN.

Study notes

Declared as a function block instance, for example TONInst : TON;
Called in ST as TONInst(IN := VarBOOL1, PT := T#5s);
Output Q is read as TONInst.Q.