is dedicated to develop the awareness and understanding about interoperability in automation
by providing best information from best sources about
open specifications that standardize the communication of acquired process data,
alarm and event records, historical data, and batch data to multi-vendor
enterprise systems and between production devices. Production devices include
sensors, instruments, PLCs, RTUs, DCSs, HMIs, historians, trending subsystems,
alarm subsystems, and more as used in the process industry, manufacturing, and
in acquiring and transporting oil, gas, and minerals.
owns all OPC trademarks including the OPC logo used throughout this site. Most of information in
OPC Knowledge Base is from OPC foundation.
Welcome to the Automation Media's OPC - OLE (Object Linking and Embedding) for Process Control
OPC Knowledge Base
OPC - Benefits to Users
Time Reduction through Lower System Integration Costs
OPC eliminates the need for costly custom software integration. OPC provides plug-and-play software and hardware components from a variety of automation software, device, and system suppliers. Process and manufacturing companies can easily integrate applications into corporate-wide automation and business systems, something that has been virtually unachievable in the past. OPC-compatible components
greatly reduce system integration costs because all software and hardware components adhere to a single, standard interface that’s being adopted around the world. Automation suppliers are providing hardware devices with integrated OPC servers that are replacing
proprietary device-driver software.The driver connection between hardware and software from different vendors has historically been the number one headache in system integration. OPC offers the
opportunity to ease the pain and shorten the application
development cycle.This gets automation projects up faster, which saves time for new projects and brings the benefit of automation to the process sooner.
Ease of Integration with Plug-and-Play (Connectivity)
PC technology is extending beyond hardware I/O to more complex control and business systems. DCS, SCADA, HMI, plant scheduling, maintenance, and other manufacturing applications supporting the OPC
standards enable the open exchange of information between cooperating applications across the manufacturing enterprise. This allows the manufacturing customer to focus his efforts on value-added business
activities versus system integration problems. The business benefit is that we have interoperability between clients and servers.The end users reap the benefit by being able to pick and choose which
components are appropriate for their installation and be assured that the components will play together.
Ease of Connectivity and Interoperability of Custom Applications
Customers may develop simple Microsoft Visual Basic applications to exchange data with any OPC server or to use their favorite OPC client application to exchange data with any OPC server.The secondary benefit is that client applications, with full access to the plant floor, can be written with little or no knowledge of the industrial network. Standardization has provided the stability necessary to encourage applications from a much wider range of software vendors and service providers.
Eliminate Proprietary Lock of Legacy Vendors
OPC client applications can focus their development on the application functionality, rather than device connectivity. Previously, customers were limited to choosing among the client applications that supported communication to the devices in their installation.
With OPC, customers are no longer bound to a single vendor. If a plant has a legacy installation, End-Users do not need to stick with the same vendor.All client applications have the same connectivity to the same set of devices.What vendors have in their repository of implemented connections will no longer be a factor in the customer’s decision to purchase an OPC client application.
If a device vendor develops a new product, it is up to the device vendor to provide the OPC interface. It is not the responsibility of every software supplier to invest thousands of dollars in new drivers.
Freedom of Choice to Pick “Best in Breed Products”
With the interoperability OPC provides, End-Users can choose software or hardware from different vendors and know that their components will seamlessly work with one another. In return, vendors will need to become more competitive to maintain their customers’ loyalty, benefiting End-Users.
OPC technology makes it possible for Systems Integrators and End-Users to select optimum, vendorindependent components when designing an automation system.This “open systems” approach enables engineers to pick products that meet their exact requirements, as opposed to modifying the requirements to match the system, regardless of the vendor.
Access to Data by Anyone in the Automation Hierarchy
Another benefit of OPC is access to process-related data at every level of the enterprise. No longer is this strategic data restricted to the plant floor.Visual Basic access via the OPC Data Access Specification permits plant data to flow upstream to the business applications. Armed with the right data, decision-makers are better
equipped to make strategic and “Just In Time” decisions to improve business efficiency.
Widespread adoption of OPC will also result in greater sharing of information across multiple applications simultaneously.As more applications are OPC-enabled, the same information may be distributed to multiple applications (such as maintenance, inventory, operator displays, and document management) using a combination of OPC and DCOM—such that business processes may be coordinated simultaneously.
Ease of Use — Auto-Configuration of Tags
Effectively designed OPC components are also very easy to use, requiring very little configuration. OPC servers do not require the user to configure tags at all; the server can automate this configuration, making an OPC installation a turnkey solution.
Reduced Troubleshooting and Maintenance Cost
OPC offers a standard that once learned minimizes the need to be an expert on every protocol.
Add/Delete without System Shutdown
Items can be added and deleted without shutting down the server.This is far superior to many proprietary drivers that require the driver be stopped before points can be added.An example of the use of this feature: points can now be added through a database front end—defining points consistent with the server’s syntax. Data will be returned immediately on an OPC Server.
Synchronous and Asynchronous Device Writes (not possible before OPC)
Synchronous and asynchronous device writes, with acknowledgment, is superior to previous DDE drivers which presented huge problems to application developers. On some DDE drivers, an application
would attempt to write a value to the PLC. However, before the value actually got to the PLC, the value would be overwritten by a polled read by the driver.
One of the benefits of using standard technology like COM, DCOM, and ActiveX is that current OPC clients will not be obsolete when new functionality is added to the server. It’s very easy to extend the OPC server by adding new COM interfaces while keeping all the existing COM interfaces backward compatible.This feature is very important to End-Users.
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