The ProcessControlItem ObjectTypedescribes a generic control loop including the measured variable to be controlled (PV), the desired value for the variable (SP) and the signal to the actuator (CV) to bring the PV to match the SP.
The ProcessItemTypeis formally defined in the following table.
Table 131– ProcessControlItemType Definition
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Attribute |
Value |
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|
BrowseName |
ProcessControlItemType |
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|
IsAbstract |
False |
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|
References |
Node Class |
BrowseName |
DataType |
TypeDefinition |
Other |
|
Subtype of the ProcessItemType, i.e. inheriting the Instance Declarations of that Node. |
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|
0:HasProperty |
Variable |
OperatorControl |
0:Boolean |
0:PropertyType |
M, RO, HR |
|
0:HasProperty |
Variable |
RemoteControlEnable |
0:Boolean |
0:PropertyType |
M, RO, HR |
|
0:HasComponent |
Variable |
RemoteValue |
0:Double |
0:BaseDataVariableType |
M, RW, HR |
|
0:HasProperty |
Variable |
RemoteControl |
0:Boolean |
0:PropertyType |
M, RW, HR |
|
0:HasComponent |
Method |
SetRemoteControl |
See below. |
M |
|
The components of the ProcessControlItemTypeare further described below.
|
BrowseName |
Description |
|
RemoteValue |
The value set by the client to override the object value. |
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RemoteControlEnable |
The RemoteControlEnablevariable exposes when the underlying system is ready to activate the RemoteControlupon a request by a client. When RemoteControlEnableis False, the underlying system is not ready and will not activate a request to remotely control the ProcessControlItem. |
|
RemoteControl |
The RemoteControlvariable lets the underlying system expose which system is currently in control of the ProcessControlItem. More specifically, if RemoteControlis True, the underlying system copies the RemoteValueto the ProcesControlItemValue to drive it, i.e. the ProcessControlItemis remotely controlled. If RemoteControlis False, the underlying system is not using RemoteValue to drive the ProcessControlItem, but another value that is exposed as the ProcessControlItemValue, i.e. the ProcessControlItemis locally controlled. A client requests (resp. releases) control of the ProcessControlItemby setting RemoteControlto True (resp. False) preferably by invoking the SetRemoteControl Method. If the client does not support methods, then the client sets RemoteControlto True. The underlying system will reset RemoteControlto False if remote control is not activated. |
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OperatorControl |
The OperatorControlvariable qualifies the source of the ProcessControlItemValue when RemoteControlis False, otherwise OperatorControlis undefined. When OperatorControlis True, the underlying system exposes the information that the ProcessControlItem Valueis modified by the operator with respect to the nominal value, e.g. NominalRate, a.k.a. design speed for a speed control loop. When OperatorControlis False, the underlying system exposes the information that the ProcessControlItem Valueis not modified by the operator. |
The SetRemoteControl Method enables or disables the remote control mode.
The signature of this Methodis specified below. Table 132specifies the Argumentsrepresentation.
Signature
SetRemoteControl (
[in] 0:Boolean Enable,
[out]MethodExecutionFeedbackType ExecutionFeedback);
Table 132– SetRemoteControl Method Arguments
|
Argument |
Description |
|
Enable |
The flag enables (True) or disables (False) the remote control mode. |
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ExecutionFeedback |
The extended feedback returning a detailed message in case of execution failure. |
When the method SetRemoteControlcompletes successfully with input argument Enableequal to True, RemoteControlis set to True and the RemoteAnalogMeasurementpersistently overrides the ProcessControlItemvalue.
When the method SetRemoteControlcompletes successfully with input argument Enableequal to False, RemoteControlis set to False and the ProcessControlItemvalue is generated by the underlying system.