Description

Function description

The function FTOF is a deactivation timer.

The additional parameters and can be configured.

Representation in FBD

Representation:

Representation in LD

Representation:

Representation in IL

Representation:

LD Enable

FTOF Presel_Value, Mem_Word, OUT_Ftof, Current_Value

Representation in ST

Representation:

FTOF(Enable, Presel_Value, Mem_Word, OUT_Ftof, Current_Value);

Description of the parameters

The following table describes the input parameters:

Parameter	Type	Comment
Enable	BOOL	"Arming" input, on the falling edge the time out starts.
Presel_Value	INT	Preset value that determines the duration (in hundredths of a second) of the time out. The maximum authorized duration is 5 minutes and 27 seconds, precise to 10 ms. Note: Modification of the Presel_Value during the time out is immediately taken into account.

The following table describes the input/output parameters:

Parameter	Type	Comment
Mem_Word	DINT	Double integer used in input and output which enables internal statuses to be stored. Be careful not to use this variable in another part of the application.

The following table describes the output parameters:

Parameter	Type	Comment
OUT _Ftof	EBOOL	Output set to 1 on rising edge of Enable and set to 0 at end of time out.
Current_Value	INT	Current value of the time out (in hundredths of a second). This variable increases from 0 to Presel_Value when the timer is launched.

EN stands for ENable; it is an optional block input. When the EN input is enabled, an ENO output is set automatically.

If EN = 0, the block is not enabled; its internal program is not executed, and ENO is set to 0.

If EN = 1, the block's internal program is run and ENO is set to 1. If an error occurs, ENO is set to 0.

If the EN input is not connected, it is set automatically to 1.

ENO

ENO stands for Error NOtification; this is the output associated with the optional input EN.

If ENO is set to 0 (because EN = 0 or in case of an execution error):

the status of the function block outputs remains the same as it was during the previous scanning cycle that executed correctly;
the output(s) of the function, as well as the procedures, are set to "0".

EBOOL

EBOOL is the abbreviation of Extended BOOLean. An EBOOL type has a value (0 (FALSE) or 1 (TRUE), but also rising or falling edges and forcing functions.

An EBOOL variable occupies one byte in memory.

The byte contains the following information:

one bit for the value;
one bit for the history (whenever the object changes state, the value is copied to the history bit);
one bit for forcing (equal to 0 if the object is not forced, or 1 if the bit is forced).

The default value of each bit is 0 (FALSE).