Configuring DCOM (Distributed COM) to Connect
an OPC client to an OPC Server on another Machine

The ability of applications (i.e. HMI/Scada clients and I/O servers) using the OLE for Process Control (OPC) standard to connect from one machine to another - i.e have the OPC client application one computer and the OPC server on another -- is quite powerful and enables many interesting applications.  However, it is probably one of the least understood aspects of using OPC by the general user population and like it or not, there are some important details one must be concerned with when setting up a system for DCOM.  This article is provided to aid our clients and prospective clients by sharing our technical expertise based on our extensive experience with DCOM and testing with our OPC Data ActiveX with both our OPC servers as well as many other OPC servers from other vendors at multiple OPC interoperability workshops.

General Information	Explanations
Introduction to DCOM (coming soon) Preface and Best Practices Introduction to DCOM Configuration Utility (DCOMCnfg.exe)	NT/2000 User Security Permissions/Considerations Special considerations in multiple domain settings

• Microsoft Reference Articles, for those who aren't afraid of lots of "under the hood, nuts and bolts" tech talk!
• DCOM Architecture
• DCOM Technical Overview

Windows 98, NT and 2000 DCOM Configuration	Windows XP and 2003 DCOM Configuration
Client side (i.e. OPC client computer) recommended settings Server side (i.e. OPC server computer) recommended settings General settings OPC Server Specific OPCEnum settings (for remote server list browsing only)	Introduction to DCOM Configuration Utility (DCOMCnfg.exe) Configuring Default DCOM options Configuring OPC Enum Configuring OPC Server PC only

Questions ? We are happy to consult with our clients who purchase and use Software Toolbox products on the specifics of any part of this tutorial as they relate to our products and the use of our products in interoperability with the products of others - that's our job and we're glad to do it. If you are not a Software Toolbox client we hope that this tutorial helps you to understand DCOM better, and we welcome your input, but are not able to provide our valuable technical support and expertise on this subject for applications that are not involving at least one of our products.  Input and client questions may be sent to DcomExpert@softwaretoolbox.com

Warning: contents of this tutorial are Copyright Software Toolbox, Inc. 2001-2002, and may not be reproduced in electronic or written form without written permission of Software Toolbox Inc. Anyone found copying copyrighted material from this site for use on another site will be prosecuted.  You are welcome to link to this site from your site.  The information in this article is accurate to the best of our professional judgment at the time of writing but is subject to change.

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