Product : ISaGRAF V3.3

Date    : 27-July-1998

File    : FC_SFC.Comparison between FC and SFC.htm

Subject : Comparison between FC and SFC

Keywords: Flow Chart - SFC - Sequential Function Chart


Here below is a comparison between FC and SFC dynamic behavior:



1- at first cycle

Begin' is 'activated

No code in 'begin' action can be executed

Initial step(s)is activated

Code of P1 actions of the initial step(s) is executed once.

Code of N actions of the initial step(s) is executed.

2- at next cycle

All possible actions and tests are performed until:

- a FC sub-program is called

- a loop is met= program tries to execute an action that has already been executed in 2nd cycle




If condition in transition(s) just after active steps is FALSE: code of N actions of active step is executed again.

If that condition is TRUE, the active step is deactivated and steps immediately following are activated:

- there is the active step de-activation, i.e. code of P0 actions is execute

- in new active step(s) code of P1 actions is executed

- in new active step(s) code of N actions is executed

3- sub-program call

Father program code is not executed until child program execution is ended.

One FC program can have only ONE of its children being executed at once.

Father program code is executed in the same time child program code is executed.

Many child programs can be executed in parrallel.

Child program execution can be interupted by father program.


Below is a vocabulary comparison between FC and SFC components

FC                   SFC

- actions         - steps

- conditions     - transistions

- sub-program    - child


Please read ISaGRAF 3.3x workbench readme file (About flow chart)

and on-line help (language reference section) for more information

on Flow Chart and SFC languages.


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