Class TcoTask

Provides basic task execution. Task is started by calling the Invoke() method. The Execute() method returns true, until the task is Done.

To get the actual state of the task, Ready, Busy, Error and Done properties are available.

Inheritance

System.Object

TcoObject

TcoTask

TcoRemoteTask

Inherited Members

TcoObject.EqualsTo(Object)

TcoObject.Messenger

TcoObject._Identity

TcoObject._messenger

System.Object.ToString()

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.ReferenceEquals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

Namespace: PlcDocu.TcoCore

Assembly: TcoCoreConnector.dll

Syntax

public abstract class TcoTask : TcoObject

Examples

Declaration part of the 'TcoTask' example.

(*

    This example shows using the 'Tcotask' application. 'TcoTask' is the simplest 
    'TcoOpen' coordination primitive.	 
    In general the body of the task could be devided into the three section: 
        1.)	Action		
        2.)	Termination condition for the expected behavior.	
        3.)	Termination condition for the non-expected behavior.	
    The body of the 'Tcotask' needs to be called cyclically. The 'Tcotask' could be then 
    invoked from 'outside'. The task of this 'Tcotask' is to ask for the favor
    (in the name of the 'TcoContext' in this example Don Corleone) and offer the return favor. 
    Task could end up the expected way in the 'DONE' state if the requested person grant 	 
    the favor or it could end up in the 'ERROR' state if the requested person refuses to grant 
    the favor. Each task could be invoked only from the 'READY' state. So if the task enters 
    the 'ERROR' state, it cannot be invoked again and has to be restored before. Anyway in this 
    example this task is never restored and invoked again as Don Corleone never asks for the 
    next favor if the first one was refused.	

*)
FUNCTION_BLOCK AskForTheFavor_Task EXTENDS TcoCore.TcoTask
VAR_INPUT
(*
    'Parameters' of this task are assigned in this example from 'outside' from the 
    'upper level' of the hierarchy, where Invoke() method is triggered.
*)
    _Person_Requested 		:	REFERENCE TO Person_Object;
    _RequestedFavor			:	STRING;
    _ReturnFavor			:	STRING;	
END_VAR

Implementation part of the 'TcoTask' example.

// THIS part needs to be called cyclically.
IF Execute() THEN
    // First section: Action.
        // Meet the right person and interpret the requirements so as a possible return favor.
        _Person_Requested.RequestForTheFavor(_RequestedFavor,_ReturnFavor);
        // Let the person requested to think carefully about the proposition.
        _Person_Requested.ThinkCarefully();
    // Second section: Termination condition for the expected behavior.
        // In the case that the requested person is "smart" and "show the respect" to the 
        // 'TcoContext', task finishes in the 'DONE' state and process of the granted the 
        // return favor should be started.  
        DoneWhen(_Person_Requested.FavorIsGranted());
    // Third section: Termination condition for the non-expected behavior.
        // In the case that the requested person is so self-confident and refuse to grant 
        // the favor, task finishes in the 'ERROR' state and automatically the OnTaskError() 
        // method is triggered. In this method normally the value of the ReturnFavor is 
        // drammatically decreased OR changed to 'Nothing'. Anyway the requested person still 
        // have the possibility to grant the favor but under different condition, as he
        // "had to do it the hard way".  
        ThrowWhen(_Person_Requested.FavorIsRefused());
END_IF

Example of the invoking this example 'TcoTask' instance 'outside' of the instance and wait if it ends-up in 'DONE' state or in 'ERROR' state.

    //Starting the execution of the 'TcoTask' instance extended by input parameters from 'outside' of the instance. 
    Thomas.AskForTheFavor(Jack_Woltz,'Grant movie role to Johny Fontane.','No future problems with unions.').Invoke();

// Checking from the 'outside' of the instance, if the task has already finished in expected way. 
    _FirstOfferAccepted := Thomas._AskForTheFavor.Done;

// Checking from the 'outside' of the instance, if the task has finished in non-expected way. 
    _FirstOfferRefused 	:= Thomas._AskForTheFavor.Error;

Constructors

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TcoTask()

Prevents creating instance of this class via public constructor

Declaration

public TcoTask()

Fields

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_abortRequest

Use to abort the executing task and set this instance back to the Ready state. The value is than set to FALSE.

Declaration

public object _abortRequest

Field Value

Type	Description
System.Object

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_elapsedTime

Declaration

public object _elapsedTime

Field Value

Type	Description
System.Object

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_enabled

Use to determine if the task execution is enabled for example from the HMI application. This value is read only, to modify it use the property Enabled

Declaration

public object _enabled

Field Value

Type	Description
System.Object

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_invokeRequest

Use to start the execution of the task from Ready state or from Done state by performing the rising edge.

Analogously to the xExecute signal of the PLCopen motion function blocks.

Declaration

public object _invokeRequest

Field Value

Type	Description
System.Object

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_isServiceable

Indicates whether the task is in serviceable state. The default state 'serviceable' that means that the task can be invoked from the higher-level application. The serviceable state is cancelled when the immediate parent is ITcoServiceable and at the same time the parent is not in servicebable state. TcoComponent is serviceable, in order for the component's task to be invokable from higher-level application component must call Service method to induce the component into serviceable state.

Declaration

public object _isServiceable

Field Value

Type	Description
System.Object

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_restoreRequest

Use to restore this instance to the Ready state. The value is than set to FALSE.

Declaration

public object _restoreRequest

Field Value

Type	Description
System.Object

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_taskState

Declaration

public short _taskState

Field Value

Type	Description
System.Int16

Properties

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AutoRestorable

Gets whether this instance is auto restorable. This is depends on the parent's settings; the value of this property is given by the parent of this object. This value is assigned after download by calling the implicit method FB_init() of the parent object and cannot be changed during runtime. The AutoRestorable property of this objects is retrieved from the EnableAutoRestore property of the parent object. This is done by calling the CheckIfAutoRestoreEnabledByParent() method inside the implicit method FB_init() after download. If this instance is the auto restorable it will call the Restore() method if:

1.) The Invoke() method has not been called for one or more cycles and starts to be called again.

2.) Parent object of this instance changes its state.

Declaration

[IgnoreReflection]
public dynamic AutoRestorable { get; }

Property Value

Type	Description
System.Object	Plc type BOOL; Twin type: Vortex.Connector.ValueTypes.OnlinerBool

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Busy

Gets whether the task is executing.

Declaration

[IgnoreReflection]
public dynamic Busy { get; }

Property Value

Type	Description
System.Object	Plc type BOOL; Twin type: Vortex.Connector.ValueTypes.OnlinerBool

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Context

Gets the context of this object. This context is given by declaration, its value is assigned after download by calling the implicit method FB_init() and cannot be changed during runtime.

Declaration

[IgnoreReflection]
public dynamic Context { get; }

Property Value

Type	Description
System.Object	Plc type ITcoContext; Twin type:

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Done

Gets whether the task has succesfully completed the execution and did not enter into the Error state.

Declaration

[IgnoreReflection]
public dynamic Done { get; }

Property Value

Type	Description
System.Object	Plc type BOOL; Twin type: Vortex.Connector.ValueTypes.OnlinerBool

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ElapsedTime

Gets the elapsed time of the execution of this task.

important

Uses `TIME` type. It might be not sutable for tasks running longer than 49 days.

Declaration

[IgnoreReflection]
public dynamic ElapsedTime { get; }

Property Value

Type	Description
System.Object	Plc type TIME; Twin type: Vortex.Connector.ValueTypes.OnlinerTime

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Enabled

Gets whether the task execution is enabled. The task can start with Invoke() method call only when this property si TRUE. If the task is Busy and this property transitions to FALSE, the task stops execution and enters Error state.

Declaration

[IgnoreReflection]
public dynamic Enabled { get; }

Property Value

Type	Description
System.Object	Plc type BOOL; Twin type: Vortex.Connector.ValueTypes.OnlinerBool

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Error

Returns true if the task has is in error state. To be able to start the the task again, Restore() method needs to be called before restarting it again calling Invoke() method.

Declaration

[IgnoreReflection]
public dynamic Error { get; }

Property Value

Type	Description
System.Object	Plc type BOOL; Twin type: Vortex.Connector.ValueTypes.OnlinerBool

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Identity

Gets identity of this TcoTask(). This value is assigned after download by calling the implicit method FB_init() and cannot be changed during runtime. This variable is used in the higher level applications.

Declaration

[IgnoreReflection]
public dynamic Identity { get; }

Property Value

Type	Description
System.Object	Plc type ULINT; Twin type: Vortex.Connector.ValueTypes.OnlinerULInt

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Ready

Gets whether the task is ready to be started (Tasks start by calling the Invoke() method).

Declaration

[IgnoreReflection]
public dynamic Ready { get; }

Property Value

Type	Description
System.Object	Plc type BOOL; Twin type: Vortex.Connector.ValueTypes.OnlinerBool

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State

Gets the actual state of this instance.

See for more details.

Declaration

[IgnoreReflection]
public dynamic State { get; }

Property Value

Type	Description
System.Object	Plc type eTaskState; Twin type:

Methods

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Abort()

Aborts the execution of this task and restores the ready state.

Declaration

[IgnoreReflection]
public void Abort()

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AutoRestore()

Private method called each time that the Execute() method is called. If this instance is auto restorable, this method ensures calling the Restore() method if:

1.) Parent object of this instance changes its state in this Plc cycle.

2.) Parent object of this instance changes its state no mather when and this instance has not yet process this change.

3.) The Invoke() method has not been called for one or more cycles and starts to be called again.

Declaration

[IgnoreReflection]
void AutoRestore()

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CheckIfAutoRestoreEnabledByParent()

Declaration

[IgnoreReflection]
void CheckIfAutoRestoreEnabledByParent()

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CheckIfCalledCyclically()

Private method called inside the Execute() method checking the cyclicall calling of this method. If this instance is auto restorable, this method ensures calling the Restore() method if the Execute() method has not been called for one or more cycles and starts to be called again.

Declaration

[IgnoreReflection]
void CheckIfCalledCyclically()

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DoneWhen(Object)

Completes the execution of this task when inCondition is true; the task transitions into Done state.

Declaration

[IgnoreReflection]
public void DoneWhen(dynamic inCondition)

Parameters

Type	Name	Description
System.Object	inCondition	Plc type : BOOL [VAR_INPUT]; Twin type : Vortex.Connector.ValueTypes.OnlinerBool

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Execute()

Returns true if the task is Busy, otherwise false. This method needs to be called cyclically.

Declaration

[IgnoreReflection]
public dynamic Execute()

Returns

Type	Description
System.Object	Plc type BOOL; Twin type: Vortex.Connector.ValueTypes.OnlinerBool

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Invoke()

Use to start the execution of the task. The starting is possible from Ready state.

Moreover it is also possible to start the task again from Done state by performing the '''rising edge''' of the calling of the Invoke() method.

Analogously to the xExecute signal of the PLCopen motion function blocks.

Declaration

[IgnoreReflection]
public dynamic Invoke()

Returns

Type	Description
System.Object	Plc type ITcoTaskStatus; Twin type:

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OnAbort()

Executes when task is aborted.

Declaration

[IgnoreReflection]
protected void OnAbort()

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OnDone()

Executes when task reaches the Done state .

Declaration

[IgnoreReflection]
protected void OnDone()

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OnError()

Executes when task reaches the Error state.

Do not confuse with WhileError(), that is called cyclically until '''Error''' state is left.

Declaration

[IgnoreReflection]
protected void OnError()

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Restore()

Restores this instance to the Ready state. Can be called explicitly or from within one of the restore mechanisms.

Declaration

[IgnoreReflection]
public dynamic Restore()

Returns

Type	Description
System.Object	Plc type ITcoRestorable; Twin type:

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ThrowWhen(Object)

When called with inCondition TRUE causes transition of the task into the Error state.

Declaration

[IgnoreReflection]
public void ThrowWhen(dynamic inCondition)

Parameters

Type	Name	Description
System.Object	inCondition	Plc type : BOOL [VAR_INPUT]; Twin type : Vortex.Connector.ValueTypes.OnlinerBool

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WhileError()

Executes until task is in Error state .

Do not confuse with OnError(), that is called just ones when '''Error''' state is entered.

Declaration

[IgnoreReflection]
protected void WhileError()