7.16 TaskControlStateMachineType

The TaskControlStateMachineType represents the behaviour of a task control and can be used for monitoring or for remote control.

To provide information about the condition of a program loaded inside a task control and the possibility to reset the loaded program the Ready State can be extended by the ReadySubstateMachineType.

The Task Control Monitor ConformanceUnit supports monitoring of the activities done by the operator or system internally. The Task Control Operation ConformanceUnit supports additional operations by Methods.

The overview of the state machine with all transitions is shown in

When the state machine changes from Executing State to Ready State caused by internal behaviour of the task control (e.g. because program is ended) it is expected that the task control can be started immediately again e.g. by the Start() method. So, the application may set the loaded program to its entry point (like the ResetToProgramStart() Method) while transition ExecutingToReady or when the Start() Method is called, that no additional reset of the program is needed.

Figure 29 – TaskControl State Machine with ReadySubstateMachine in Ready State

7.16.1 Overview

Figure 30 – TaskControlStateMachineType with the ReadySubstateMachine

The TaskControlStateMachineType is formally defined in Table 65.

The Ready State of TaskControlStateMachineType has additional subcomponents which are defined in Table 66.

The states of the TaskControlStateMachineType are described in Table 67.

The transitions are described in the table below.

The components of the TaskControlStateMachineType have additional references which are defined in Table 69.

The component Variables of the TaskControlStateMachineType have additional Attributes defined in Table 70.

7.16.2 LoadByNodeId Method

The signature of this Method is specified below.

Signature

	LoadByNodeId (
		[in]	0:ExpandedNodeId	 Id
	   [out]	0:Int32	 Status
	);
	

Table 71 specifies the Arguments.

The LoadByNodeId Method is called by a Client to load a program or a module into a task control.

For the storage of programs, the Server may support the Programs folder defined within the ControllerType. (see 7.18). This method can be used to load the program or module into the Task Control if the program or module itself is available in the address space (e.g. within the Programs folder). The Id input argument shall be used to identify the program in the address space. This method can be a synchronous or an asynchronous method. In case it is a synchronous method, the return output arguments may contain more information about the Success or Failure of the method call. If the system is in the Idle state when the method is called, and something goes wrong internally then instead of the IdleToReady transition, the IdleToIdle transition shall be observed by the client. If the system is already in the Ready state and the LoadByNodeId is called and fails, it is system dependent, whether the system goes back to the Idle state or remains in the Ready state. Calling LoadByNodeId in the Executing state will fail in normal circumstances.

The possible Method result codes are formally defined in Table 72. Some of these StatusCodes correspond to the ProgramId input argument.

Clients may inspect the Status output argument to determine if the program was successfully loaded or if it failed.

The LoadByNodeId Method representation in the AddressSpace is formally defined in Table 73.

7.16.3 LoadByName Method

The signature of this Method is specified below.

Signature

	LoadByName (
		[in]	0:String	Name
	   [out]	0:Int32	Status
	);
	

The table below specifies the Arguments.

The LoadByName Method is called by a Client to load a program or module to a task control. The controller uses the Name input argument to identify the program or module to load into the task control. The behaviour of this method is identical to the LoadByNodeId (see 7.16.2).

The possible Method result codes are formally defined in the table below. Some of these StatusCodes correspond to the Name input argument.

Clients may inspect the Status output argument to determine if the program was successfully loaded or if it failed.

The LoadByName Method representation in the AddressSpace is formally defined in the table below.

7.16.4 UnloadProgram Method

The signature of this Method is specified below.

Signature

	UnloadProgram (
		[out]	0:Int32	    Status
	);

The table below specifies the Arguments.

The UnloadProgram Method is called by a Client to unload the program from a task control.

The possible Method result codes are formally defined in the table below.

The UnloadProgram Method representation in the AddressSpace is formally defined in the table below.

7.16.5 UnloadByNodeId Method

The signature of this Method is specified below.

Signature

	UnloadByNodeId (
	   [in]    0:ExpandedNodeId    Id
		[out]	0:Int32	    Status
	);

Table 80 specifies the Arguments.

The UnloadByNodeId Method is called by a Client to unload a task module from a task control. This only works if the task modules are expressed in the address space (7.22).

The possible Method result codes are formally defined in the table below.

The UnloadByNodeId Method representation in the AddressSpace is formally defined in Table 82. This method might not always result in a state change from Ready to Idle.

7.16.6 UnloadByName Method

The signature of this Method is specified below.

Signature

	UnloadByName (
	   [in]    0:String    Name  
		[out]	0:Int32      Status
	);

Table 83 specifies the Arguments.

The UnloadByName Method is called by a Client to unload a module from a task control. This can be used to unload the task modules if they are not expressed in the address space and internal logic is used to find the module to be unloaded based on the Name input argument.

This method might not always result in a state change from Ready to Idle.

The possible Method result codes are formally defined in the table below.

The UnloadByName Method representation in the AddressSpace is formally defined in the table below.

7.16.7 Start Method

The signature of this Method is specified below.

Signature

	Start (
		[out]	0:Int32	Status
	);
	

Table 86 specifies the Arguments.

The Start method can only be successfully called when the task control is in the Ready state. Depending on the program pointer, the system shall attempt to start executing from the beginning of the program or continue executing from where it was suspended (see Substate machine description of this state in 7.17).

The possible Method result codes are formally defined in Table 87.

The Start Method representation in the AddressSpace is formally defined in Table 88.

7.16.8 Stop Method

The signature of this Method is specified below.

Signature

	Stop (
	[in]	0:Int64 	StopMode
	[out]	0:Int32	Status
	);

Table 89 specifies the Arguments.

The Stop Method allows an authorized Client to command the task control to stop executing and leave the Executing state and go to the Ready state. If the ReadySubstateMachine (see 7.17) is present, the task control shall be in the Suspended state of the Substate machine.

The input argument StopMode must be either 0 or one of those listed in the PossibleStopModes Variable (see Section). If not, then a Bad_InvalidArgument Result Code is returned.

The possible Method result codes are formally defined in the table below.

The Stop Method representation in the AddressSpace is formally defined in Table 91.