TOF / TOFR

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Function Block A function block groups an algorithm and a set of private data. It has inputs and outputs. - Off timer.

Inputs

Input	Data Type	Range	Description
IN	BOOL	FALSE, TRUE	Timer command.
PT	TIME		Programmed The act of performing a sequence of instructions or commands. time.
RST	BOOL	FALSE, TRUE	Reset New start of the microprocessor. (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 When the step gets activated, the action is activated for a single execution, and possibly once again when the step is deactivated. 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 A function calculates a result according to the current value of its inputs. 
A function has no internal data and is not linked to declared instances. 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;