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An Overview of OPC SECTION 17 Using CX-Supervisor as an OPC Client
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In the case of OPC these interfaces for each of the DCOM objects are defined
within the relevant specifications. This guide only deals with the OPC Data
Access specification Custom (used by C++) and Automation (used by script
languages and VB) interfaces.
17-1-3-2 What are the benefits of OPC?
Asking what the business benefits of OPC are is like asking what the benefits
of plug-and-play technology are to the computer industry. More choices, better
access to process data, ease of plug-and-play operation, and efficient
utilization of development resources are the main benefits of OPC technology.
OPC brings the value that comes with the use of standards, including reduced
training costs, reduced custom development costs, and lower long-term
maintenance costs. By design, OPC-compliant products work seamlessly with
one another. With this plug-and-play approach, off-the-shelf components can
be brought together efficiently to solve immediate requirements. In addition,
long-term maintenance and upgrading can be achieved by removing and
replacing individual components in a system without any work needed to "wire
up" the new pieces. To illustrate the savings, imagine the increase in cost if
every household appliance had its own type of wall plug. Eliminating
customisation drastically reduces the cost of an automation system by saving
money during acquisition, installation, and maintenance.
17-1-3-3 Freedom of choice
With the introduction of OPC-compliant manufacturing automation products,
users are provided their due right to select and implement systems comprised
of best-in-class components without the pain of custom interfaces. This user
benefit is sometimes referred to as "freedom of choice." For example, both
Netscape and Internet Explorer can browse the web equally well, but people
use the browser they like best. As a result of this freedom of choice, vendors
will need to become more competitive and offer superior products and
solutions to maintain their customers. Besides freedom of choice, the user
also has vendor independence, or "freedom from a proprietary lock." If the
implemented control system is comprised of modules with proprietary
interfaces, any customer who desires to upgrade any component function of
the integrated whole is entirely dependent on the vendor. With OPC
components, only the module of interest must be upgraded and not the entire
system. The requirement to use the original vendor is eliminated. High-priced
proprietary solutions (and their expensive after-sale support contracts) will
yield to lower cost OPC-enabled alternatives.
17-1-3-4 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.