SF_TON (FB)

Description of the function block

Tip

The version of the function block as described here corresponds to the latest version of the function block in Version list of function blocks.

Tip

SF_TON is a timer function block from the SafetyStandard library. It is an extension of TON, a standard IEC 61131-3 function block. The SF_TON function block contains both standard data types and safety-oriented data types (prefix: SAFE).

SF_TON is a timer function block from the SafetyStandard standard library that implements a switch-on delay.

If the IN input changes from FALSE to TRUE, then the output also changes to TRUE, but only after the expiry of the delay time.

Figure 119. Function block: SF_TON

Table 101. VAR_INPUT

Name	Data Type	Initial Value	Description, parameter values
`IN`	`BOOL`	`FALSE`	Rising edge (`FALSE` -> `TRUE`): Time delay starts. Falling edge (`TRUE` -> `FALSE`): Reset of the time delay.
`PT`	`TIME`	`TIME#0ms`	Delay time in milliseconds (ms) (Upper limit for counting up `ET`).

Name

Data Type

Initial Value

Description, parameter values

IN

BOOL

FALSE

Rising edge (FALSE -> TRUE): Time delay starts.

Falling edge (TRUE -> FALSE): Reset of the time delay.

PT

TIME

TIME#0ms

Delay time in milliseconds (ms) (Upper limit for counting up ET).

Table 102. VAR_OUTPUT

Name	Data Type	Initial Value	Description, parameter values
`Q`	`SAFEBOOL`	`FALSE`	Rising edge as soon as `ET` has reached the upper limit of the time delay (`PT`). `TRUE` when `IN = TRUE` and `ET = PT`
`ET`	`TIME`	`TIME#0ms`	Current state of the delay time. Starts counting up as soon as `IN = TRUE` and stops when `ET = PT`.

Name

Data Type

Initial Value

Description, parameter values

Q

SAFEBOOL

FALSE

Rising edge as soon as ET has reached the upper limit of the time delay (PT).

TRUE when IN = TRUE and ET = PT

ET

TIME

TIME#0ms

Current state of the delay time. Starts counting up as soon as IN = TRUE and stops when ET = PT.

Figure 120. Timing diagram: SF_TON