Engineering Tip

DcomWiz Versions

The DcomWiz utility from UGS remained relatively stable until Microsoft released XP Service Pack 2. Due to widespread changes in DCOM security beginning with XP Service Pack 2, major changes were made in the DcomWiz utilities. The particular version of DcomWiz that you will need to run on YOUR system will depend on the FactoryLink version and Operating System version including Service Pack level. If you are not sure what is the latest version to use, please contact Danco Systems Technical Support.

Com/Dcom FAQ for FactoryLink Users.

• Always run Dcomwiz after installing FactoryLink or any post-release updates that install com/dcom components. The version currently available from the Support Online download page is the one that will be released with FL72 and will support FL70 and FL71 as well. This features user validation, correctly sets the autostart user, and a warning when an Administrator with no password is being used in XP. Always check the download page for the latest Dcomwiz update.

• Local users are not the same as Domain users. e.g. MyComputer\fluser is not the same user as MyDomain\fluser. The Windows security model validates these as different users.

• Do not use an Adminstrator account with blank or empty password in XP. This has never been a good practice, and Microsoft now discourages users from leaving the password blank by restricting access to network components when the Administrator password is blank in XP.

• In Windows 2000 and XP, the user entered in Dcomwiz must be at least a Power User. A standard user no longer has the needed permissions to launch FL.

• The user that starts the FactoryLink Server should always be the same user as defined in Dcomwiz. If a different user starts FactoryLink remote clients will not be able to connect to the FactoryLink server objects. One way to see this is login as a different user and launch FactoryLink from Configuration Explorer (CE). Clients should be able to connect. Then launch FactoryLink from a commandline. Clients will probably not be able to now connect. When you launch FactoryLink from CE, it calls a com object called FLUtilityLauncher which inherits the identity set by Dcomwiz. FactoryLink is called by FLUtilityLauncher so it in turn inherits the identity of the user defined in FLUtilityLauncher. One way around this issue is to autostart FactoryLink. The Autostart user identity is also always the user entered in Dcomwiz.

• Not necessarily a Com/Dcom issue but when XP systems are used, Simple File Sharing should be disabled. Having Simple File Sharing enabled can create problems with FLFM, FLREST, FLSAVE, FVARCHIVE, and other file-centric tasks when running to network shares. NOTE: Permissions and access rights to network shares may change or be lost when disabling Simple File Sharing.

• When running in a Workgroup, all users are authenticated on the local machine. This means each user name and password must be identical on all machines in the workgroup. The user defined in Dcomwiz must also be present and enabled on all machines within the workgroup.

• Good host name resolution is an absolute must between all stations within a FactoryLink system. You should be either running a solid, stable DNS Server, or you should have all clients and servers defined in the hosts file. With no other name resolution methods defined, Hosts file, DNS, etc., Windows relies on Netbios to resolve names. The way Netbios resolves names is by broadcasting a name registration request and then waits to see who responds. The problem with this method is it generates a high amount of network traffic. If there is enough traffic, this method of name resolution can actually become inoperable. This can make the system appear stable when the network traffic is not heavy but cause loss of data and connectivity when the system becomes loaded. Microsoft discourages user from relying on Netbios for host name resolution.

• Use Static IP addressing for the FactoryLink Server machines. Do not rely on DHCP for something as important a server.

• The next 2 suggestions can be configured by using the Netwiz tool available on the Support Online download page.

• Disable Media Sense if it is possible the computer will be disconnected from the network at any time. Starting with Windows 2000, Microsoft introduced a feature called Media Sense. Media Sense detects whether or not the computer is actually connected to media(a valid ethernet connection) at runtime. If it finds it is not, it disables the network services. This means some of the FactoryLink tools and objects that rely on RPC Services will no longer work correctly. USDATA has provided a Network Wizard (Netwiz) to disable media sense. The downside of disabling media sense is that it will probably take longer for your computer to boot. This is due to the fact Windows is trying to enable the network services but cannot. It will timeout after a short time leaving the network services running. This is no different than it was in the days of NT4.0.

• Disable Automatic Private IP Addressing on the FactoryLink Servers. Starting with Windows 2000, a feature called Automatic Private IP Addressing(APIPA) was introduced. If the IP addresses for your computers are being assigned by DHCP and the DHCP server fails, then computers with APIPA enabled will revert to a private IP address. It will always start with 169.254.*.*. This means clients who find the servers by hostname may not be able to locate the FactoryLink Server.

• Before installing FactoryLink for the first time, be sure you are logged on as a user with full administrative rights. Verify you are able to browse your own computer through the Network Neighborhood. If the prerequisite Microsoft network services have not been installed or have been disabled, not being able to browse is an indication of the system not being ready for installing FactoryLink.

• When you are experiencing connection problems between client and server objects, always take a look at the system event logs and look for possible com/dcom errors. Remember some com/dcom errors may be expected. For example, if you launch Client Builder without FactoryLink running, you will see com/dcom connection and timeout failures in your event log. This is because the OPC Server and Alarm Server cannot run without the FactoryLink Server running. Of course you will see errors saying the object can't be found or the object didn't responsd within the expected time limit.

• Do not run Windows 2000 with less than Service Pack 3 installed. There are some known com/dcom issues in Windows 2000 that have been addressed by Service Pack 3.