SF_CTU (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_CTU is a counter FB from the SafetyStandard library. It is an extension of CTU, a standard IEC 61131-3 function block. The SF_CTU function block contains both standard data types and safety-related data types (prefix: SAFE).

Its function is the counting up of a counter to a defined upper limit.

Figure 111. Function block: SF_CTU

Table 87. VAR_INPUT

Name	Data Type	Initial Value	Description, parameter values
`CU`	`BOOL`	`FALSE`	Rising edge at `CU` increments `CV` by 1.
`RESET`	`BOOL`	`FALSE`	`TRUE`: Resets the `CV` counter to 0.
`PV`	`SAFEINT`	`0`	Upper limit for counting up `CV`.

Table 88. VAR_OUTPUT

Name	Data Type	Initial Value	Description, parameter values
`Q`	`SAFEBOOL`	`FALSE`	`TRUE`: Counter `CV` has reached the upper limit `PV`.
`CV`	`SAFEINT`	`0`	Current counter value. Increments until `PV` is reached.

FB code

IF R THEN CV := 0 ;
ELSIF CU AND (CV < PVmax)
    THEN CV := CV+1;
END_IF ;
Q := (CV >= PV) ;

The numerical value of PVmax is 32767.