History of Field Data Access |
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History of OPC
| 2000 | Windows 2000 NT 5.0 | |
| 1999 | XML | |
| 1998 | ||
| 1997 | OPC Data Access Specification 1.0A
OPC Europe, OPC Japan |
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| 1996 | Windows NT 4.0 & DCOM | |
| 1995 | Windows 95 | |
| 1994 | OLE 2.1 (32-bit) | |
| 1993 | Object Linking & Embedding 2.0 | |
| 1992 | WinSEM committee Windows 3.1 & Object Linking & Embedding 1.0 |
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| 1991 | ||
| 1990 | Windows 3.0 & Dynamic Data Exchange | |
| 1982 | DOS |
Windows 2000
Microsoft Windows 2000 ( NT 5.0) provides a significant upgade over NT 4.0 adding Active Directory, Dynamic Domain Naming Service, Intellimirror Power Management and FAT32 filing system. It is an is ideal platform to host OPC Servers.
Windows 98
Microsoft Windows 98 was released in the June 1998 and is an incremental upgade to the Windows 95 operating system bringing together various upgrades, patches and technology releases that Microsoft has made since Windows 95's release.
Windows 98 is an important release for the process control industry as it is a proven affordable, multi-tasking operating system with integrated DCOM support for distributed computing and therefore direct support for OPC Servers technologies.
OPC Specification V1.01
The next offering from the OPC Foundation is to be Version 1.01 of the OPC Specification. This specification will build on the existing specification and address issues raised from feedback to the original specification.
OPC Technical Committees
In order to manage the full range of issues relating to process control data the OPC Foundation has formed a number of Technical Committees to research and design enhancements to the OPC Specification. The Technical Committees include:
» OPC Revision 1.01
» Compliance Testing
» Marketing
» Historical Data Access
» Event Logging
» Security
» SP95 Liaison
» Standard Naming Conventions
» Batch
OPC Foundation
The OPC Foundation was formed on 30th August 1996, just after the release of Version 1.0 of the OPC Specification, as an independent, non-profit organisation with the task of managing the OPC Standard. The Foundation has since established off-shoots to cover Europe and Asia (OPC Japan).
The charter of the OPC Foundation is:
"To develop an open and interoperable interface standard, based upon the functional requirements of OLE/COM and DCOM technology, that fosters greater interoperability between automation/control applications, field systems/devices, and business/office applications."
Windows NT 4.0 & DCOM
Windows NT 4.0 was released in 1996 with much fanfare. The new operating system combined the proven reliabiltiy of Windows NT 3.5 with the acclaimed user interface from Windows 95. Windows NT also included integrated support for Microsoft's Distributed Common Object Model (DCOM) allowing applications to create and work with objects residing on other computers across a network.
DCOM (formerly Network OLE) provides the blueprint for true distributed computing allowing server and client applications to pass data across a network in a standard manner. This facility means that process control data from an OPC Server can be accessed by client applications.
OPC Specification V1.0 & 1.0A
The OPC Specification version 1.0 was released on August 29 1996. A revised specification Version 1.0A was released in September 1997 under the revised name OPC Data Access Specification in order to differentiate it from future OPC Specifications resulting from the various OPC Technical Committees. The specification is available in Microsoft Word format from the OPC Foundation.
Windows 95
Windows 95 was finally released towards the end of 1995. It sported a new user interface based on extensive research and polling by Microsoft's designers.
The OPC Task Force
The OPC Task Force went public at the 1995 ISA Show in New Orleans with a news release announcing the aims of the group. The first members consisted of Fisher-Rosemount, Intellution, Intuitive Technology, OPTO 22, Rockwell Software and Microsoft which was to be involved in a supportive and consultative role.
The first draft version of the OPC specification was released in December 1995, and was presented to the last WinSEM gathering in Redmond in January 1996. Despite a certain amount of pique due to the initial perception that a group had run away with the standardisation effort, the overall response was favourable and very constructive.
A second draft specification followed in March 1996, and 'JumpStart' seminars were held in Dallas, Texas (April 1996), London, England (July 1996), and Japan (August 1996) to give interested developers a fast track introduction to the proposed standard. On each occasion the response was very positive. The Powerpoint slides used at the first OPC JumpStart are still available at ftp://zilker.net/pub/opc/JumpStart.
OLE 2.0
When OLE 2.0 was launched in 1992, it was apparent that it would eventually replace nearly all uses of DDE. It was more flexible, more robust, and used more efficient transport mechanisms.
WinSEM
WinSEM (the Windows Science, Engineering, and Manufacturing) is a group of developers of technical software which has been meeting regularly at Microsoft's Redmond headquarters since April 1992. Members are primarily from the area of PC-based industrial controls (process and discrete) and PC-based data acquisition. There are also members from industrial image processing and general scientific applications.
WinSEM has focused on the use of OLE techniques for moving process data between applications in (almost) real-time. In particular, a number of SCADA vendors saw the chance to standardise the interface between the SCADA core and the device drivers which were actually responsible for acquiring the data. Potentially, this could benefit both SCADA vendors and equipment manufacturers: the SCADA vendor would not need to invest valuable effort in writing drivers, while the equipment manufacturer would have to provide only one driver which would work with all Windows software.
Despite various paper arising from within WinSEM, advancement towards a standard was slow. It was the view of a number of the those involved in the WinSEM effort (including Microsoft) that a smaller, more tightly focused group would be needed to ensure timely delivery of a standard. This was the origin of the OPC Task Force.
Windows 3.0 & Dynamic Data Exchange
Windows 3.0 was released in 1990 and with it came the ability for an inexpensive, mainstream computing platform to run multiple applications simultaneously. Just as importantly Windows 3.0 provided Dynamic Data Exchange (DDE), a standard mechanism for those applications to exchange data at runtime.
Dynamic Data Exchange enabled users to link general purpose applications, such as Microsoft Excel, to process data from field devices. Unfortunately DDE had severe limitations. It was not terribly robust, its bandwidth was limited and there was no support for transferring data across a network.
Various attempts were made trying to overcome these shortcomings, including Wonderware's Fast DDETM and Rockwell Software's AdvanceDDETM. These methods greatly increased the effective bandwidth by packing multiple data items into each packet. The main drawback of this scheme was that they again became proprietary systems, requiring payments to their vendors, and thereby guaranteeing that they would never attain the status of a true industry standard.
DOS
Since the earliest days of computers engineers have been attempting to link their field equipment to their computer systems. In the dark DOS ages computers could only perform a one task at a time and each application had to have its own drivers for external devices such as printers and programmable logic controllers.