OLE for Process Control (OPC) is a set of specifications defining
communication interfaces between a host computer system and a device
used for industrial automation.  OPC is based on the Microsoft
COM family of
technologies and now exists as the industry standard used by all major
equipment and SCADA software manufacturers.  Several vendors have
emerged that provide drivers for all prevalent programmable controllers and

The most common analogy used is the comparison to printer drivers.  Before
the Windows standard, developers had to write drivers for all major printer
brands.  With the standard, a single printer driver is installed into Windows for
all applications to use.  OPC provides the same functionality by allowing
communications with industrial equipment through an installed driver.

Since drivers are available from the original equipment manufacturers and/or
third parties, the list of supported devices continues to grow and hundreds of
drivers are currently available.  OPC drivers are built once, used in multiple
products, and are subjected to strenuous compliance testing insuring the
most reliable and stable platform for moving critical process data.

As more SCADA vendors embrace OPC technology, seamless interconnectivity
is now possible.  Dissimilar systems now have a direct link to share data
between them.  An investment in OPC is an investment in the future as
systems can be expanded by integrating on the supervisory level without the
costs associated with replacement.

An international organization was founded to ensure the interoperability in
automation by creating and maintaining the interface standards.  The
Foundation now has over 360 members from around the world including
nearly all the major providers of control systems, instrumentation, and
process control software.  Microsoft acts as a technology advisor providing
previews of upcoming technology changes while actively exercising their
membership standing.