Rockwell-automation Logix5000 Controllers Sequential Function Charts P Manuale Utente Scaricare il pdf (Pagina 25)

Design a sequential function chart Chapter 1

Use actions to divide a step into the different functions that the step performs,

such as commanding a motor, setting the state of a valve, or placing a group of

devices in a specific mode.

How do you want to use the action?

There are two types of actions.

If you want to Then

• Execute structured text directly in the SFC

• Call a subroutine

• Use the automatic reset option to reset data upon leaving a step

Use a non-Boolean action on page 25

•

Only set a bit and program other logic to monitor the bit to determine

when to execute.

Use a Boolean action on page 26

Use a non-Boolean action

A non-Boolean action contains the logic for the action. It uses structured text to

execute assignments and instructions or call a subroutine.

With non-Boolean actions, you also have the option to postscan (automatically

reset) the assignments and instructions before leaving a step.

• During postscan the controller executes the assignments and instructions as

if all conditions are FALSE.

• The controller postscans both embedded structured text and any subroutine

that the action calls.

To automatically reset assignments and instructions, see

Turn off a device at the

end of a step on page 35.

Add actions for each step

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Rockwell-automation Logix5000 Controllers Sequential Function Charts P Manuale Utente Pagina 25