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Term |
Definition of Term |
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Camera |
Vision sensor that is capable of extracting information from electro-magnetic waves. |
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Client |
Receiver of information. Requests services from a server, usually OPC Machine Vision system. |
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Configuration |
Information stored in a configuration ensures that different vision systems generate equal results if same recipe is used. |
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Environment |
The set of external entities working with the vision system in one way or another, e.g. PLC, MES, etc. |
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External |
Not part of the vision system or the OPC UA server; may refer to the automation system, the manufacturing execution system or other entities |
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Job |
The main purpose of a machine vision system is to execute jobs. Job may be a simple task such as measurement of a part’s diameter, or much more complex, like surface inspection of a long, continuous roll of a printing paper. |
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Machine Vision System |
A system for machine vision is any complex information processing system / smart camera / vision sensor / other component which, in the production context, is capable of extracting information from electro-magnetic waves in accordance with a given image processing task. |
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Inline Machine Vision System |
Denotes a machine vision system which is used in the manner of a system working continuously within a production line (hence the name). This can mean 100% quality inspection, as well as providing poses for robot-guidance for all parts or inspection of the entire area of a continuous material stream and other similar use cases. |
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Product |
In an industrial environment a machine vision system is usually used to check products that are manufactured. The name of such a product is often used outside the machine vision system to reference recipes of the devices used to manufacture the product. This eliminates the need for the external production control systems to know the IDs of local recipes of each device. |
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Recipe |
Properties, procedures and parameters that describe a machine vision job for the vision system are stored in a recipe. The actual content of the data structure is out of the scope of this specification. |
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Server |
Information provider classified by the services it provides. Vision system commonly acts as OPC UA server. |
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State Machine |
A finite-state machine (FSM) or simply a state machine, is a mathematical model of computation. It is an abstract machine that can be in exactly one of a finite number of states at any given time. The state machine can change from one state to another in response to some external inputs. The change from one state to another is called a transition. A state machine is defined by a list of its states, its initial state, and the conditions for each transition. |
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System-wide unique |
Used in conjunction with identifiers and handles to denote that at any given time no other entity of the same type and meaning shall exist in the OPC UA server with the same value. No further assumptions about global or historical uniqueness are made; especially in the case of identifiers, however, globally unique identifiers are recommended. |
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Vision System |
The underlying machine vision system for which the OPC UA server provides an abstracted view. |
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WebSocket |
WebSocket is a computer communications protocol, providing full-duplex communication channels over a single TCP connection. |
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Abbreviation |
Definition of Abbreviation |
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AC |
Alarm and Condition |
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BLOB |
BLOB, a Binary Large Object is a collection of binary data stored as a single entity in a database management system. |
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DCS |
DCS, a distributed control system is a computerised control system for a process or plant usually with a large number of control loops, in which autonomous controllers are distributed throughout the system, but there is central operator supervisory control. The DCS concept increases reliability and reduces installation costs by localising control functions near the process plant, with remote monitoring and supervision. |
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ERP |
ERP, the Enterprise resource planning is the integrated management of core business processes, often in real-time and mediated by software and technology. |
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HMI |
The user interface or human–machine interface is the part of the machine that handles the human–machine interaction. |
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HTTP |
The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, and hypermedia information systems. |
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ID |
Identifer |
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MES |
MES, manufacturing execution systems are computerized systems used in manufacturing, to track and document the transformation of raw materials to finished goods. MES provides information that helps manufacturing decision makers understand how current conditions on the plant floor can be optimized to improve production output. |
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PLC |
PLC, a programmable logic controller, or programmable controller is an industrial digital computer which has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, or robotic devices, or any activity that requires high reliability control and ease of programming and process fault diagnosis. |
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PMS |
PMS, the Product Manufacturing System is generally a non-critical system for manufacturing activities, as it establishes a communication with the board line systems that directly and physically handle production progress. |
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TCP/IP |
The Internet protocol suite is the conceptual model and set of communications protocols used on the Internet and similar computer networks. It is commonly known as TCP/IP because the foundational protocols in the suite are the Transmission Control Protocol (TCP) and the Internet Protocol (IP). |
Node definitions are specified using tables (see Table 4).
Attributes are defined by providing the Attribute name and a value, or a description of the value.
References are defined by providing the ReferenceType name, the BrowseName of the TargetNode and its NodeClass.
- If the TargetNode is a component of the Node being defined in the table, the Attributes of the composed Node are defined in the same row of the table.
- The DataType is only specified for Variables; “[number>]” indicates a single-dimensional array, for multi-dimensional arrays the expression is repeated for each dimension (e.g. [2][3] for a two-dimensional array). For all arrays the ArrayDimensions is set as identified by <number> values. If no <number> is set, the corresponding dimension is set to 0, indicating an unknown size. If no number is provided at all the ArrayDimensions can be omitted. If no brackets are provided, it identifies a scalar DataType and the ValueRank is set to the corresponding value (see OPC 10000-3). In addition, ArrayDimensions is set to null or is omitted. If it can be Any or ScalarOrOneDimension, the value is put into “{<value>}”, so either “{Any}” or “{ScalarOrOneDimension}” and the ValueRank is set to the corresponding value (see OPC 10000-3) and the ArrayDimensions is set to null or is omitted. Examples are given in Table 3.
Table 3 – Examples of DataTypes
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Notation |
DataType |
ValueRank |
ArrayDimensions |
Description |
|
Int32 |
Int32 |
-1 |
omitted or null |
A scalar Int32. |
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Int32[] |
Int32 |
1 |
omitted or {0} |
Single-dimensional array of Int32 with an unknown size. |
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Int32[][] |
Int32 |
2 |
omitted or {0,0} |
Two-dimensional array of Int32 with unknown sizes for both dimensions. |
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Int32[3][] |
Int32 |
2 |
{3,0} |
Two-dimensional array of Int32 with a size of 3 for the first dimension and an unknown size for the second dimension. |
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Int32[5][3] |
Int32 |
2 |
{5,3} |
Two-dimensional array of Int32 with a size of 5 for the first dimension and a size of 3 for the second dimension. |
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Int32{Any} |
Int32 |
-2 |
omitted or null |
An Int32 where it is unknown if it is scalar or array with any number of dimensions. |
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Int32{ScalarOrOneDimension} |
Int32 |
-3 |
omitted or null |
An Int32 where it is either a single-dimensional array or a scalar. |
- The TypeDefinition is specified for Objects and Variables.
- The TypeDefinition column specifies a symbolic name for a NodeId, i.e. the specified Node points with a HasTypeDefinitionReference to the corresponding Node.
- The ModellingRule of the referenced component is provided by specifying the symbolic name of the rule in the ModellingRule column. In the AddressSpace, the Node shall use a HasModellingRuleReference to point to the corresponding ModellingRuleObject.
If the NodeId of a DataType is provided, the symbolic name of the Node representing the DataType shall be used.
Nodes of all other NodeClasses cannot be defined in the same table; therefore only the used ReferenceType, their NodeClass and their BrowseName are specified. A reference to another part of this document points to their definition.
Table 4 illustrates the table. If no components are provided, the DataType, TypeDefinition and ModellingRule columns may be omitted and only a Comment column is introduced to point to the Node definition.
Table 4 – Type Definition Table
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Attribute |
Value |
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Attribute name |
Attribute value. If it is an optional Attribute that is not set “--“ will be used. |
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References |
NodeClass |
BrowseName |
DataType |
TypeDefinition |
ModellingRule |
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ReferenceType name |
BrowseName of the target Node. If the Reference is to be instantiated by the server, then the value of the target Node’s BrowseName is “--“. |
DataType of the referenced Node, only applicable for Variables. |
TypeDefinition of the referenced Node, only applicable for Variables and Objects. |
Referenced ModellingRule of the referenced Object. |
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NOTE Notes referencing footnotes of the table content. |
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Components of Nodes can be complex that is containing components by themselves. The TypeDefinition, NodeClass, DataType and ModellingRule can be derived from the type definitions, and the symbolic name can be created as defined in Section 3.3.3.1. Therefore, those containing components are not explicitly specified; they are implicitly specified by the type definitions.
The NodeIds of all Nodes described in this standard are only symbolic names. Annex B defines the actual NodeIds.
The symbolic name of each Node defined in this specification is its BrowseName, or, when it is part of another Node, the BrowseName of the other Node, a “.”, and the BrowseName of itself. In this case “part of” means that the whole has a HasProperty or HasComponentReference to its part. Since all Nodes not being part of another Node have a unique name in this specification, the symbolic name is unique.
The namespace for all NodeIds defined in this specification is defined in Table 200. The namespace for this NamespaceIndex is Server-specific and depends on the position of the namespace URI in the server namespace table.
Note that this specification not only defines concrete Nodes, but also requires that some Nodes shall be generated, for example one for each Session running on the Server. The NodeIds of those Nodes are Server-specific, including the namespace. But the NamespaceIndex of those Nodes cannot be the NamespaceIndex used for the Nodes defined in this specification, because they are not defined by this specification but generated by the Server.
The text part of the BrowseNames for all Nodes defined in this specification is specified in the tables defining the Nodes. The NamespaceIndex for all BrowseNames defined in this specification is defined in Annex A.
If the BrowseName is not defined by this specification, a namespace index prefix like ‘0:EngineeringUnits’ or ‘2:DeviceRevision’ is added to the BrowseName. This is typically necessary if a Property of another specification is overwritten or used in the OPC UA types defined in this specification. Table 200 provides a list of namespaces and their indexes as used in this specification.
The Attributes of Nodes, their DataTypes and descriptions are defined in OPC 10000-3. Attributes not marked as optional are mandatory and shall be provided by a Server. The following tables define if the Attribute value is defined by this specification or if it is server-specific.
For all Nodes specified in this specification, the Attributes named in Table 5 shall be set as specified in the table.
Table 5 – Common Node Attributes
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Attribute |
Value |
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DisplayName |
The DisplayName is a LocalizedText. Each server shall provide the DisplayName identical to the BrowseName of the Node for the LocaleId “en”. Whether the server provides translated names for other LocaleIds is server-specific. |
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Description |
Optionally a server-specific description is provided. |
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NodeClass |
|
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NodeId |
The NodeId is described by BrowseNames as defined in 3.3.2.1. |
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WriteMask |
Optionally the WriteMaskAttribute can be provided. If the WriteMaskAttribute is provided, it shall set all non-server-specific Attributes to not writable. For example, the DescriptionAttribute may be set to writable since a Server may provide a server-specific description for the Node. The NodeId shall not be writable, because it is defined for each Node in this specification. |
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UserWriteMask |
Optionally the UserWriteMaskAttribute can be provided. The same rules as for the WriteMaskAttribute apply. |
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RolePermissions |
Optionally server-specific role permissions can be provided. |
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UserRolePermissions |
Optionally the role permissions of the current Session can be provided. The value is server-specifc and depend on the RolePermissionsAttribute (if provided) and the current Session. |
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AccessRestrictions |
Optionally server-specific access restrictions can be provided. |
For all Objects specified in this specification, the Attributes named in Table 6 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.
Table 6 – Common Object Attributes
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Attribute |
Value |
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EventNotifier |
Whether the Node can be used to subscribe to Events or not is server-specific. |
For all Variables specified in this specification, the Attributes named in Table 7 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.
Table 7 – Common Variable Attributes
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Attribute |
Value |
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MinimumSamplingInterval |
Optionally, a server-specific minimum sampling interval is provided. |
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AccessLevel |
The access level for Variables used for type definitions is server-specific, for all other Variables defined in this specification, the access level shall allow reading; other settings are server-specific. |
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UserAccessLevel |
The value for the UserAccessLevelAttribute is server-specific. It is assumed that all Variables can be accessed by at least one user. |
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Value |
For Variables used as InstanceDeclarations, the value is server-specific; otherwise it shall represent the value described in the text. |
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ArrayDimensions |
If the ValueRank does not identify an array of a specific dimension (i.e. ValueRank <= 0) the ArrayDimensions can either be set to null or the Attribute is missing. This behaviour is server-specific. If the ValueRank specifies an array of a specific dimension (i.e. ValueRank > 0) then the ArrayDimensionsAttribute shall be specified in the table defining the Variable. |
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Historizing |
The value for the HistorizingAttribute is server-specific. |
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AccessLevelEx |
If the AccessLevelExAttribute is provided, it shall have the bits 8, 9, and 10 set to 0, meaning that read and write operations on an individual Variable are atomic, and arrays can be partly written. |
For all VariableTypes specified in this specification, the Attributes named in Table 8 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.
Table 8 – Common VariableType Attributes
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Attributes |
Value |
|
Value |
Optionally a server-specific default value can be provided. |
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ArrayDimensions |
If the ValueRank does not identify an array of a specific dimension (i.e. ValueRank <= 0) the ArrayDimensions can either be set to null or the Attribute is missing. This behaviour is server-specific. If the ValueRank specifies an array of a specific dimension (i.e. ValueRank > 0) then the ArrayDimensionsAttribute shall be specified in the table defining the VariableType. |
For all Methods specified in this specification, the Attributes named in Table 9 shall be set as specified in the table. The definitions for the Attributes can be found in OPC 10000-3.
Table 9 – Common Method Attributes
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Attributes |
Value |
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Executable |
All Methods defined in this specification shall be executable (ExecutableAttribute set to “True”), unless it is defined differently in the Method definition. |
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UserExecutable |
The value of the UserExecutableAttribute is server-specific. It is assumed that all Methods can be executed by at least one user. |