Rockwell-automation Logix5000 Controllers Sequential Function Charts P Manuale Utente Scaricare il pdf (Pagina 50)

Chapter 1 Design a sequential function chart

Select the Execute until FALSE transition option only when either of these are

true:

• You do not have to update JSR parameters before each step. Parameters

update only when the SFC returns to the JSR.

• A FALSE transition occurs within the watchdog timer for the task. If the

time that it takes to return to a JSR and complete the rest of the task is

greater than the watchdog timer, a major fault occurs.

Two optional instructions are available that give you further control over the

execution of your SFC.

If you want to Then use this instruction

Pause an SFC Pause SFC (SFP)

Reset an SFC to a specific step or stop Reset SFC (SFR)

Both instructions are available in the ladder logic and structured text

programming languages.

The following diagrams show the execution of an SFC with different

organizations of steps or different selections of execution options.

• Execution of a sequence

• Execution of a simultaneous branch

• Execution of a selection branch

• When parameters enter and exit an SFC

• Options for execution control

Pause or reset an SFC

Execution diagrams

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Rockwell-automation Logix5000 Controllers Sequential Function Charts P Manuale Utente Pagina 50