OPC Server


Thread Starter


We want to integrate an OPC communication, from our applications (on line and laboratory sensors ) to mill data acquisition.
1)What's exactly OPC? How does it work?
2)What are the mains functions to implement
3)Do you know if there is standard OPC server which could be integrated in our application?
4)Is it possible to use an OPC server
OPC (OLE for Process control) is a software API developed by the OPCFoundation http://www.opcfoundatation.org to standardise communication to field devices.
Most HMI/Scada software already have the OPC client interface, which can be used to read and write to any OPC Server. You can buy third
party OPC Servers or write it for your own proprietary device. You can buy C++ toolkits to help you write OPC Servers. You can configure
your own OPC Server without writing any C++ code by using our user definable driver. We have users that develop their own OPC Server this
way for talking to their weighers, scales, tank farms, windmills, GPS and etc.,

Philip Wong
[email protected]

Walter Bennett

The OPC Specification is a non-proprietary technical specification that defines a set of standard interfaces based upon Microsoft's OLE/COM
technology. The application of the OPC standard interface makes possible interoperability between automation/control applications, field systems/devices and business/office applications.

For more information visit "http://www.opcfoundation.org":http://www.opcfoundation.org it contains all the
latest specifications. As to question 3. Kep servers works really good they have an reliable
interface that is easy to understand and configure and its fairly inexpensive. "http://www.kepware.com":http://www.kepware.com looks at those two site and they
should answer any question you have. As an integrator I highly recommend OPC. Over the convention DDE.

Walter Bennett
Systems Intergrator
Ph: 469-358-0882
mailto:[email protected]
Answers to questions:

1) OPC stands for "Ole for Process Control". The name originates from the use of OLE (now known as the Component Object Model - COM) as the enabling
technology for systems interoperability in the automation and control arena. OPC now encapsulates several publicly available standards which are created and maintained by the OPC Foundation (www.opcfoundation.org). The most
widely adopted standard from the Foundation is the OPC Data Access Standard (OPC DA), which is primarily oriented to the deliverance of real-time data. There are also OPC standards for Alarms & Events (A&E), Historical Data Access (HDA), and batch data. What each of these standards define are a set of software interfaces, based on COM, that will allow client applications to read/write process data in a standardized manner. The benefit, of course,
derives from the fact that a single OPC client can now get process data from any number of OPC servers.

2) The specification defines which are required and which are optional interfaces.

3) If your application/system already supports a "common" industrial protocol (e.g. Modbus/Modbus+) then an off-the-shelf OPC server can be integrated in your application. Otherwise, you will need to create an OPC
server for your application/system/device. There are Toolkits available to expedite this process (see www.nordyn.com for one from Northern Dynamic).

4) There are tens of thousands of OPC nodes running on the factory floor today. They are predominantly Microsoft Windows NT/2000 workstations. COM is also available for non-Microsoft platforms (e.g. Linux, VxWorks), but I
can't say how many of these systems provide OPC connectivity.

Best regards,
Gord Ellis

Gord Ellis, P.Eng.
Northern Dynamic Inc. (OPC Foundation Member)
J103-155 Frobisher Drive
Waterloo, Ontario
Canada N2V 2E1
Tel/Fax: (519) 725-2071/2072