Short summary

Name	`TON`
→POU type	→function block
Category	IEC-block, Timer
Conform to →IEC-standard	no restrictions
Graphical interface
Available since	version 1.4.1 (for logi.CAD 3)

Functionality

This is an edge delay where the turning-on edge is delayed.

Enter the delay period at input PT. If input IN is →turned on and the delay period is over, output Q returns value TRUE (or an equivalent). Output ET returns the expired time since turning input IN on, until the value entered at PT is reached and as long as the input IN is turned on.

Implementer-specific realization

The IEC-standard does not specify whether and how to consider changes for input PT while the functionality is executed. In logi.CAD 3, the expired time is always compared with the current value of PT. Thus, if input PT is changed after input IN has been turned on, the behavior of the block is affected.

This block receives the current system time from the runtime system. This time remains constant while the same task is executed. However, in case of different tasks, it is possible that a different system time is used when the belonging programs are executed (even if the different tasks have the same cycle time).

The following illustration shows the behavior of TON:

images/download/attachments/414782946/TON-version-1-modificationdate-1535107073599-api-v2.png

In-/outputs

	Identifier	→Data type	Description
Inputs :	`IN`	`BOOL`	input/start
Inputs :	`PT`	`TIME`	preset time
Outputs :	`Q`	`BOOL`	output
Outputs :	`ET`	`TIME`	elapsed time

Input EN and output ENO are available when →calling the block. See "Execution control: EN, ENO" for information on input EN and output ENO.

See:

"Blocks for safe logic" whether this block is supported for developing safety-relevant applications.
"Highlighting safe logic in the FBD-editor" for the effects when using the block as a block for safe logic .

Example for usage within ST-editor

Simple call of TON

PROGRAM Test
	VAR
	    ton1      : TON;
        elapsed   : BOOL;
	END_VAR
	ton1(IN := TRUE, PT := T#2s, Q => elapsed);
    (* Instance of block 'TON' is called. Variable 'elapsed' is set to TRUE after 2 seconds. *)
END_PROGRAM

Timer program with call of TON

PROGRAM Timer
	VAR
	    ton1     : TON;
	    count    : INT;
	    duration : TIME;
	    ton_q    : BOOL;
	    temp     : BOOL;
	    trigger  : BOOL;
	END_VAR
	
	duration := T#2s;
	temp := NOT(ton_q);
	trigger := AND(temp, TRUE);
	ton1(IN := trigger, PT := duration, Q => ton_q);   (* Instance of block 'TON' is called.  *)
	count := ADD(EN := ton_q, IN1 := count, IN2 := 1);
END_PROGRAM

When creating your application within the ST-editor, enter a call of a block by typing the text as requested by the syntax or use Content Assist.