Because of the controversy surrounding it, Microsoft will be releasing Service Pack 2 (SP2) for Windows XP on August 25, and many experts say don’t load it. Microsoft has developed a registry key that will permit Automatic Update to bypass SP2 and still download other updates. Many enterprise users are still concerned, since new issues have cropped up, like the incompatibility of some VPNs with SP2.
IBM, for example, posted a note on its corporate intranet, telling its employees not to download SP2 because of compatibility issues. The OPC Foundation says, “Installing Service Pack 2 with the default configuration will inhibit OPC communications via DCOM.” And Lenson Wong, marketing communications director for Berkeley Process Control, says, “We are telling everybody not to install it if they are using our communications software. It should be treated like a brand new OS not a service pack.”
The OPC Foundation has prepared a white paper with instructions for configuring Service Pack 2 for use with OPC/DCOM communications. It is available at www.opcfoundation.org/WebUI/DownloadFile.aspx?CM=1&RI=161.
Jim Luth, OPC Foundation Technical Director, told us, “Short term, SP2 will negatively affect most other industrial LAN communication software running on Windows XP, not just OPC. In all cases, configuration changes should allow it to work again.”
We contacted a few software vendors in the process control industry, and they mostly agree. “The rumors are only partly true,” says John Weber, president of Software Toolbox. “It is not a non-reversible action. XP SP2, through its firewalling and other security measures, will block DCOM connections unless the user makes some changes to the XP security configuration after installing XP SP2. By default, XP SP2 installs with more services locked down than ever before, in an effort to make the OS more secure against virus, hacks, and other exploits. The downside of that is that more services than ever before will be blocked or turned off by default."
Weber points out that the OPC Foundation’s white paper tells how to properly setup an XP SP2 system to allow DCOM to work. Weber also promises to have a similar white paper up on his website by Monday, providing direction to his customers.
“Keep in mind that SP2 only affects remote connections, not local OPC Server/Client interactions,” says Mark Hensley, President of Kepware Technologies. “We are working on our own product specific versions of the white paper and we are also doing step-by-step tutorials on making the changes to SP2.”