Microsoft's Windows XP SP2 (service pack 2) is mostly concerned with network security issues to protect users from unauthorized/malicious network access to their computers (such as from viruses). As a result, SP2 changes various default settings in Windows that affect communication by blocking access with remote PCs (for example, it turns on a firewall). Consequently, these changes can affect OPC communication. However, users can easily configure their Windows PCs to enable OPC communication again, as described in the following document, "Using OPC via DCOM with Microsoft Windows XP Service Pack 2".
Thus, Windows XP SP2 will block communication with any OPC products (including Matrikon's). However, by properly configuring Windows, users can undo any issues caused by the upgrades. Once these changes are done, communication will resume as expected and there will not be any compatibility issues with Matrikon's OPC products and Windows XP SP2.
While these changes may be possible for most applications, there may be some situations where users are be unable to make the necessary changes. In these cases, MatrikonOPC recommends MatrikonOPC Tunneller.