TOF / TOFR

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 Function Block - Off timer.

Inputs

Input

Data Type

Range

Unit

Default

Description

IN

BOOL

FALSE, TRUE

 

 

Timer command.

PT

TIME

 

 

 

Programmed time.

RST

BOOL

FALSE, TRUE

 

 

Reset (TOFR only).

Outputs

Output

Data Type

Range

Unit

Description

Q

BOOL

FALSE, TRUE

 

Timer elapsed output signal.

ET

TIME

 

 

Elapsed time.

Remarks

  • TOFR is same as TOF but has an extra input for resetting the timer.
  • The timer starts on a falling pulse of IN input.
    • It stops when the elapsed time is equal to the programmed time.
  • A rising pulse of IN input resets the timer to 0 (zero).
  • The output signal is set to TRUE when the IN input rises to TRUE.
    • It is reset to FALSE when the programmed time is elapsed.

Time Diagram

Figure 1: Time Diagram

FBD Language Example

FFLD Language Example

  • In the FFLD Language, the input rung is the IN command.
    • The output rung is Q the output signal.

IL Language Example

(* MyTimer is a declared instance of TOF function block *) 
Op1: CAL MyTimer (IN, PT)
     FFLD  MyTimer.Q
     ST  Q
     FFLD  MyTimer.ET
     ST  ET

ST Language Example

(* MyTimer is a declared instance of TOF function block *)
MyTimer (IN, PT);
Q := MyTimer.Q;
ET := MyTimer.ET;

See Also