The OPC Foundation has defined interfaces to OPC Data Access Servers, Alarm and Event Servers, Batch Servers, and Historical Data Access Servers. These servers acquire data from the plant floor and move it vertically into the enterprise system.
In contrast, OPC Data eXchange (OPC DX) has been designed to move plant floor data horizontally between OPC DA servers. By presenting this new technology, the OPC DX enables data interoperability between OPC based systems (including DCOM and XML based systems running over Ethernet) including PLCs, HMI/SCADA, Devices, and PCs.
The purpose of this document is to continue OPC’s goal of enabling and promoting interoperability of applications.
This document defines abstract services used to configure horizontal data transfers from servers with OPC DA interfaces to OPC DX servers. This document contains appendices that map these abstract services to specific interface technologies (e.g. Web Services and COM).
OPC DX does not specify a new method for these data transfers. Instead, it relies on OPC Data Access (OPC DA) data transfer capabilities already in use today. This document defines the behavior of the OPC DX server as it relates to control and monitoring the data transfer from DA servers to itself.
This specification is intended for developers of OPC compliant DX Clients and Servers. It is assumed that the reader is familiar with Microsoft COM, Web Services, XML, and SOAP. It is also recommended that the reader review the reference documents described in Section 1.5.
OPC DX, in contrast to OPC DA, is used primarily for horizontal data flows between OPC servers. OPC DX is designed to provide for the direct transfer of data from one or more OPC DA and DX servers to an OPC DX server, without the need for intermediate clients or servers to access the data from one server and forward it to another.
To support these capabilities, OPC DX has the