If any of you think you might use DAQ OPC on Windows XP computers, this email might save you a whole lot of headache.
Those who have used the OPC server for NI DAQ, have probably had to mess with DCOM security settings in order to get it to work. NI has some of this documented on their web site. However - there is one setting you have to change for Windows XP that they don't mention. Apparently, the default setup for XP forces remote users to authenticate as Guest. (there must be a logical reason Microsoft changed this - but it is beyond me) This means that DCOM clients (OPC) can not connect to a server on an XP machine unless the Guest account is activated AND has sufficient rights to launch the server. Here is how you change this setting: Go to "Administrative Tools" > "Local Security Policy" > "Local Policies" > "Security Options" > "Network access: Sharing and security model for local accounts" You need to change this setting to "Classic - users authenticate as themselves". After doing this you won't need to activate the Guest account. It has taken me WEEKS to discover this! I am really ticked of that this wasn't documented somewhere for those of us who aren't experts with Windows XP networking. Now hopefully I can finally get down to writing some software! (with my luck - one of you will now find this documented in a user manual or somewhere silly like that :) Now to inform the NI support engineer who was just as confused as myself. John Howard
