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F O U N D A T I O N
Using OPC via DCOM
with
Microsoft Windows XP Service Pack 2
Version
Karl-Heinz Deiretsbacher, Siemens AG
Jim Luth, ICONICS, Inc.
OPC Foundation Technical Director
Rashesh Mody, Invensys/Wonderware
OPC Foundation Chief Architect
Kurt T Haus, Advosol Inc.
®
Using OPC via DCOM with Version
Microsoft Windows XP
F O U N D A T I O N
Service Pack 2
Abstract
The major goal of Windows XP Service Pack 2 is to mon available
scenarios for malicious attack on Windows XP. The Service Pack will reduce the
effect of mon attacks in four ways:
1. Improvement in shielding Windows XP from work
a. RPC and munication enhancements
b. Enhancements to the internal Windows firewall
2. Enhanced memory protection
3. Safer handling of e-mail
4. Explorer security enhancements.
Most OPC Clients and Servers use DCOM municate over work and
thus will be impacted due to the changes in Service Pack 2. When Service Pack
2 is installed with its default configuration settings, munication via
DCOM will cease to work. This paper describes the settings necessary to restore
munication when using XP Service Pack 2 (SP2).
SP2 includes many changes and security enhancements, two of which directly
impact OPC via DCOM. First new DCOM limit settings have been added.
Secondly the software firewall included with XP has been greatly enhanced and
is turned on by default.
Since the callback mechanism used by OPC essentially turns the OPC Client into
a DCOM Server and the OPC Server into a DCOM Client, the instructions
provided here must be followed on all nodes that contain either OPC Servers or
OPC Clients.
Note: munication that is confined to a single machine (, but
not DCOM) will continue to work properly after installing XP SP2 without
following the instructions in this