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OLE for process control

 

 
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OLE for process control
 
 
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OLE for Process Control (OPC) which stands for Object Linking and Embedding
Object Linking and Embedding

Object Linking and Embedding is a technology that allows embedding and linking to documents and other objects developed by Microsoft. For developers, it brought OLE custom controls , a way to develop and use custom user interface elements....
 (OLE) for Process Control
Process control

Process control is a statistics and engineering discipline that deals with architectures, Mechanism s, and algorithms for controlling the output of a specific process....
, is the original name for a standards
Standardization

Standardization is the process of developing and agreeing upon Standard . A standard is a document that establishes uniform engineering or technical specifications, criteria, methods, processes, or practices....
 specification developed in 1996 by an industrial automation industry task force
Task force

A task force is a temporary Military organization established to work on a single defined task or activity. Originally introduced by the United States Navy, the term has now caught on for general usage and is a standard part of NATO terminology....
. The standard specifies the communication of real-time plant data between control devices from different manufacturers.

After the initial release, the OPC Foundation
OPC Foundation

The Object Linking and Embedding for Process Control Foundation is an consortium that creates and maintains standards for open connectivity of industrial automation devices and systems....
 was created to maintain the standard. Since then, standards have been added and names have been changed.






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OLE for Process Control (OPC) which stands for Object Linking and Embedding
Object Linking and Embedding

Object Linking and Embedding is a technology that allows embedding and linking to documents and other objects developed by Microsoft. For developers, it brought OLE custom controls , a way to develop and use custom user interface elements....
 (OLE) for Process Control
Process control

Process control is a statistics and engineering discipline that deals with architectures, Mechanism s, and algorithms for controlling the output of a specific process....
, is the original name for a standards
Standardization

Standardization is the process of developing and agreeing upon Standard . A standard is a document that establishes uniform engineering or technical specifications, criteria, methods, processes, or practices....
 specification developed in 1996 by an industrial automation industry task force
Task force

A task force is a temporary Military organization established to work on a single defined task or activity. Originally introduced by the United States Navy, the term has now caught on for general usage and is a standard part of NATO terminology....
. The standard specifies the communication of real-time plant data between control devices from different manufacturers.

After the initial release, the OPC Foundation
OPC Foundation

The Object Linking and Embedding for Process Control Foundation is an consortium that creates and maintains standards for open connectivity of industrial automation devices and systems....
 was created to maintain the standard. Since then, standards have been added and names have been changed. As of June, 2006, "OPC is a series of standards specifications". (Seven current standards and two emerging standards.) "The first standard (originally called simply the OPC Specification"), is "now called the Data Access Specification", or (later on the same page) "OPC Data Access
OPC Data Access

The OPC Data Access Specification is the first of a group of specifications known as the OPC Specifications.OPC Data Access is a group of standards that provides specifications for communicating real-time data from data acquisition devices such as PLCs to display and interface devices like Human-Machine Interfaces ....
", or OPC Data Access Specification.

While OPC originally stood for "OLE for Process Control", the official stance of the OPC Foundation is that OPC is no longer an acronym and the technology is simply known as "OPC". One of the reasons behind this is while OPC is heavily used within the process industries, it can be, and is, widely used in discrete manufacturing
Discrete manufacturing

Discrete manufacturing varies from Process Manufacturing. In discrete manufacturing, the manufacturing floor works off orders to build something....
 as well. Hence, OPC is known for more than just its applications within process control.

Origin and uses

The OPC Specification was based on the OLE
Object Linking and Embedding

Object Linking and Embedding is a technology that allows embedding and linking to documents and other objects developed by Microsoft. For developers, it brought OLE custom controls , a way to develop and use custom user interface elements....
, COM
Component Object Model

Component Object Model is an interface standard for software componentry introduced by Microsoft in 1993. It is used to enable interprocess communication and dynamic object creation in a large range of programming languages....
, and DCOM
Distributed component object model

Distributed Component Object Model is a proprietary software Microsoft technology for communication among software componentry distributed across networked computers....
 technologies developed by Microsoft for the Microsoft Windows
Microsoft Windows

Microsoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces ....
 operating system family. The specification defined a standard set of object
Object (computer science)

In its simplest embodiment, an object is an allocated region of storage. Since programming languages use variable#Computer_programmings to access objects, the terms object and variable are often used interchangeably....
s, interfaces
Interface (computer science)

Interface generally refers to an Abstraction_%28computer_science%29 that an entity provides of itself to the outside. This separates the methods of external communication from internal operation, and allows it to be internally modified without affecting the way outside entities interact with it, as well as provide Polymorphism in object-orien...
 and methods
Method (computer science)

In object-oriented programming, a method is a subroutine that is exclusively associated either with a class or with an object . Like a procedure in procedural programming languages, a method usually consists of a sequence of statement to perform an action, a set of input parameter to customize those actions, and possibly an output value...
 for use in process control and manufacturing automation applications to facilitate interoperability
Interoperability

Interoperability is a property referring to the ability of diverse systems and organizations to work together . The term is often used in a technical systems engineering sense, or alternatively in a broad sense, taking into account social, political, and organizational factors that impact system to system performance....
.

OPC was designed to bridge Windows based applications and process control hardware and software applications. Standard defines consistent method of accessing field data from plant floor devices. This method remains the same regardless of the type and source of data.

OPC servers provide a method for many different software packages to access data from a process control device, such as a PLC
Programmable logic controller

A programmable logic controller or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, control of amusement rides, or control of lighting fixtures....
 or DCS
Distributed control system

A distributed control system refers to a control system usually of a manufacturing system, process or any kind of dynamic system, in which the controller elements are not central in location but are distributed throughout the system with each component sub-system controlled by one or more controllers....
. Traditionally, any time a package needed access to data from a device, a custom interface, or driver, had to be written. The purpose of OPC is to define a common interface that is written once and then reused by any business, SCADA
SCADA

SCADA stands for Supervisory Control And Data Acquisition. It generally refers to an industrial control system: a computer system monitoring and controlling a process....
, HMI, or custom software packages.

Once an OPC server
Opc server

An OPC Server is a software application that acts as an API or protocol converter. An OPC Server will connect to a device such as a Programmable logic controller, DCS, Remote Terminal Unit, or a data source such as a database or User interface, and translate the data into a standard-based OPC format....
 is written for a particular device, it can be reused by any application that is able to act as an OPC client. OPC servers use Microsoft’s OLE technology (also known as the Component Object Model, or COM) to communicate with clients. COM technology permits a standard for real-time information exchange between software applications and process hardware to be defined.

Future

The OPC Unified Architecture
OPC Unified Architecture

OPC Unified Architecture is the most recent OLE for process control specification from the OPC Foundation and differs significantly from its predecessors....
 (UA) has been specified and is being tested and implemented through its Early Adopters program. It can be implemented with Java
Java (programming language)

Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java ....
, Microsoft .NET, or C
C (programming language)

C is a general-purpose computer programming language originally developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories to implement the Unix operating system....
, eliminating the need to use a Microsoft Windows
Microsoft Windows

Microsoft Windows is a series of software operating systems and graphical user interfaces produced by Microsoft. Microsoft first introduced an operating environment named Windows in November 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces ....
 based platform of earlier OPC versions. UA combines the functionality of the existing OPC interfaces with new technologies such as XML and Web Services to deliver higher level MES and ERP
Enterprise resource planning

Enterprise resource planning is an enterprise-wide information system designed to coordinate all the resources, information, and activities needed to complete business processes such as order fulfillment or billing....
 support. It looks to become the standard for exchanging industrial data, replacing FactoryTalk, Archestra, some Modbus
Modbus

Modbus is a serial communications protocol published by Modicon in 1979 for use with its programmable logic controllers . It has become a de facto Standardization communications protocol in industry, and is now the most commonly available means of connecting industrial Electronics devices....
 applications, and OPCDA
OPC Data Access

The OPC Data Access Specification is the first of a group of specifications known as the OPC Specifications.OPC Data Access is a group of standards that provides specifications for communicating real-time data from data acquisition devices such as PLCs to display and interface devices like Human-Machine Interfaces ....
.

Reference


External links

  • - Unofficial OPC Resource Center]