state machines with codesys: clever usage of language … · 2014. 7. 6. · close gate . wait for...

CODESYS® a trademark of 3S-Smart Software Solutions GmbH

State machines with CODESYS: Clever usage of language properties CODESYS Users' Conference 2014, Manfred Werner

2 © 3S-Smart Software Solutions GmbH

State machines with CODESYS

Agenda

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Task assignment and definitions

A PLC classic: Function Block Diagram

A CODESYS standard: Structured Text

Rather unusual: CFC

A specialist: Sequential Function Chart

New in the family: UML State Chart

Conclusion

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© 3S-Smart Software Solutions GmbH

A process shall be automated.

Different programming languages shall be used.

The question arises which example to take?


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A car washing plant

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A first approach


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In order to ensure an actual comparison, the same process will be automated using different programming languages.


Close gate Wait for 3 seconds Open gate

To keep the process as simple as possible, objects have already been created which "only" have to be commanded. These objects take care of themselves to decide whether and how the command can be carried out.

The basic knowledge for all programming language will be acquired through the programming of a rolling gate.

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State

Transition condition

Transition

OPEN

Action

CLOSED X

Close!

Open!

Sensor open

Sensor closed



Agenda

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Rather unusual: CFC



Conclusion

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State


State Transition condition

None of the classics Function Block Diagram (FBD), Ladder Logic (LD) or Instruction List (IL) knows states.

However, states can be presented through variables. Typically,

− the IEC operators R or S − instances of the function block

RS or SR from the standard library

− a conditionally assigned state variable are used.


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Current state

Future state

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Using a method creates an overview!


Current state

Future state

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Actions are handled separated from the process. Mostly, physical outputs are assigned

cyclically. SafetyCondition

− What should always be complied with − What should never occur


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Sequence programming in Function Block Diagram is possible. can be read if certain structures are respected. Alternative branches are possible for running the program. Programmers have much freedom. The value of the state variable can easily be saved.



Agenda

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Rather unusual: CFC



Conclusion

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In ST, a CASE structure is used practically always.


State


Action

Transition

Current state Future state

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Only the current state is executed.


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Sequence programming in Structured Text Is possible. Alternative branches are possible for running the program. Programmers have much freedom. The value of the state variable can easily be saved. Only the code which is actually relevant is calculated.

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Rather unusual: CFC



Conclusion

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Option 1 Same procedure as in Function Block Diagram

Option 2 The states are specialized FBs.

− Execute: Execute action. − Done: Action finished

Rather unusual: CFC

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Programming by connecting

Rather unusual: CFC

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Online: a dream!

Rather unusual: CFC

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Rather unusual: CFC

Sequence programming in Continuous Function Block Diagram is possible. Programming by simple wiring. Alternative branches are difficult to display. States are easy and clearly recognizable in the monitoring. Specialized FBs are necessary.



Agenda

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Rather unusual: CFC



Conclusion

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SFC is defined in the IEC61131-3.

In addition to the action associations defined in the IEC, CODESYS offers an easier option to execute actions.


State


Action association

Transition

Action

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Unique online display Active action / step Fulfilled transition


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A specialist has special features.


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A specialist has special features.

The state can be queried with:


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Sequence programming in Sequential Function Chart Is possible. Graphical display of the sequence. Alternative or parallel branches are feasible without tricks. States are clearly recognizable in the monitoring. Flags for diagnostics and influencing are available. Only active actions are calculated.



Agenda

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Rather unusual: CFC



Conclusion

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State Chart is an additional programming language included in the CODESYS UML Package.

It is available in the CODESYS Store.

It requires a dongle.

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State


Transition

Action

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Unique online display Active state

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Special feature: Composite State

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Implicit flags to influence states

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A special asset of the State Chart: Multiple transitions between states

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Sequence programming in the State Chart is possible. Graphical display of the sequence. States are clearly recognizable in the monitoring. Implicit variables for diagnostics and influencing are available. Only active actions are calculated.



Agenda

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Rather unusual: CFC



Conclusion

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Have it your own way!

Decision criteria: How shall the program be used? Who shall program? Who shall put it into operation / carry out the diagnosis? Which language fits the task best? Which kind of presentation fits best for project documentation?

Conclusion


Inspiring Automation Solutions

Thank you for your attention.

State machines with CODESYS:�Clever usage of language propertiesFoliennummer 2Task assignment and definitionsTask assignment and definitionsTask assignment and definitionsTask assignment and definitionsFoliennummer 7A PLC classic: Function Block DiagramA PLC classic: Function Block DiagramA PLC classic: Function Block DiagramA PLC classic: Function Block DiagramA PLC classic: Function Block DiagramFoliennummer 13A CODESYS standard: Structured Text A CODESYS standard: Structured Text A CODESYS standard: Structured Text Foliennummer 17Rather unusual: CFCRather unusual: CFCRather unusual: CFCRather unusual: CFCFoliennummer 22A specialist: Sequential Function ChartA specialist: Sequential Function ChartA specialist: Sequential Function ChartA specialist: Sequential Function ChartA specialist: Sequential Function ChartFoliennummer 28New in the family: UML State ChartNew in the family: UML State ChartNew in the family: UML State ChartNew in the family: UML State ChartNew in the family: UML State ChartNew in the family: UML State ChartNew in the family: UML State ChartFoliennummer 36ConclusionFoliennummer 38

state machines with codesys: clever usage of language … · 2014. 7. 6. · close gate . wait for...

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