Specifications

RSLinx – Training Guide B - 7
Introduction
Readers Guide
This document serves as an overview to OPC. It gives background information, motivation,
architectural highlights and an abstract for each OPC topic.
Specific interface specifications to develop OPC clients and/or OPC Servers (e.g., for
DataAccess, Alarm&Event Handling or Historical DataAccess) and a specification for
interfaces that are common for all OPC Servers are available as separate documents.
Chapter 1 gives some background information. It describes the purpose of OPC and why
and how both vendors and customers have advantages in using OPC.
Chapter 2 provides a technical overview, describing the fundamentals of the design and
characteristics of OPC components.
Chapter 3 describes the way OPC supports browsing of servers both locally and on remote
machines.
OPC Background
A standard mechanism for communicating to numerous data sources, either devices on the
factory floor, or a database in a control room is the motivation for OPC.
The information architecture for the Process Industry shown in Figure 0-1 involves the
following levels:
Field Management. With the advent of “smart” field devices, a wealth of information can
be provided concerning field devices that was not previously available. This information
provides data on the health of a device, its configuration parameters, materials of
construction, etc. All this information must be presented to the user, and any applications
using it, in a consistent manner.
Process Management. The installation of Distributed Control Systems (DCS) and SCADA
systems to monitor and control manufacturing processes makes data available electronically
which had been gathered manually.
Business Management. Benefits can be gained by installing the control systems. This is
accomplished by integrating the information collected from the process into the business
systems managing the financial aspects of the manufacturing process. Providing this
information in a consistent manner to client applications minimizes the effort required to
provide this integration.
To do these things effectively, manufacturers need to access data from the plant floor and
integrate it into their existing business systems. Manufacturers must be able to utilize off
the shelf tools (SCADA Packages, Databases, spreadsheets, etc.) to assemble a system to
meet their needs. The key is an open and effective communication architecture
concentrating on data access, and not the types of data.