TOF

Timer with switch-off delay

The function block TOF allows you to program a switch-off delay, e.g. to switch off the ventilator of a machine at a later point in time than the machine itself.

Parameters

Input

IN (BOOL)

timer ON

an internal timer is started if a falling edge is detected at IN. If a rising edge is detected at IN before PT has reached its value, Q will not be switched off

PT (TIME)

switch-off delay (PT = preset time)

16-bit value: 0–327.27s

32-bit value: 0–21,474,836.47s (32-bit value not available for FP3, FPC, FP5, FP10/10S)

resolution 10ms each

Output

Q (BOOL)

signal output

reset (FALSE) if PT = ET

ET

elapsed time

indicates the current value of the elapsed time

The value can be changed during counting operation by writing to the variable from the programming editor.

Remarks

Q is switched off with a delay corresponding to the time defined in PT. Switching on is carried out without delay.
If IN (as in the time chart t3 to t4) is set prior to the lapse of the delay time PT, Q remains set (time chart for t2 to t3).

Time chart

Example

POU header

All input and output variables used for programming this function have been declared in the POU header. The same POU header is used for all programming languages.

	VAR
		copy_name: TOF;
		start: BOOL:=FALSE;
		set_value: TIME:=T#0s;
		signal_output: BOOL:=FALSE;
		current_value: TIME:=T#0s;
	END_VAR

POU body

If start is reset, this signal is transferred to signal_output with a delay corresponding to the period of time set_value.

LD body

BODY
    WORKSPACE
        NETWORK_LIST_TYPE := NWTYPELD ;
        ACTIVE_NETWORK := 0 ;
    END_WORKSPACE
    NET_WORK
        NETWORK_TYPE := NWTYPELD ;
        NETWORK_LABEL :=  ;
        NETWORK_TITLE :=  ;
        NETWORK_HEIGHT := 6 ;
        NETWORK_BODY
B(B_FB,TOF!,copy_name,9,1,14,5,,?BIN?BPT?AQ?AET);
B(B_CONTACT,,start,3,2,5,4,);
B(B_VARIN,,set_value,7,3,9,5,);
B(B_VAROUT,,current_value,14,3,16,5,);
B(B_COIL,,signal_output,21,2,23,4,);
L(1,3,3,3);
L(5,3,9,3);
L(14,3,21,3);
L(1,0,1,6);
        END_NETWORK_BODY
    END_NET_WORK
END_BODY

ST body

copy_name( IN:= start ,
        PT:= set_value ,
        Q=> signal_output ,
        ET=> current_value );

IL body

If you want to call the function block in an instruction list, enter the following:

CAL	copy_name(IN:= start,, PT:= set_value,, Q:= signal_output,, ET:= current_value,)