You must set up a NetDDE share for the DDE server (the program being controlled). This share is similar to file and print shares of Windows95 as it acts as an alias for a resource that other computers can use to refer to that resource. Hence, the client application, which is the program doing the controlling does not require a share to be specified. For example, if you are wanting to access Citect trend or variable data via Excel, then you will need to create a Citect share on the Citect PC.

To create NetDDE shares it is necessary to edit the Registry. This can be done manually by making entries in the \HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NetDDE\DDE Shares key of the Servers Registry. However this is heavily underdocumented and not advised.. Alternatively use a NetDDE share manager such as DDESHR to make the Registry changes for you. These are generally 16-bit applications which will run under Workgroups and Win95. DDESHR allows you to specify: a Share Name, Topic Name, Item Name(optional) and 2 levels of password secured access. For each level of access you can specify the clients authority to start an application on connect, request, advise, poke and execute commands/data.

Under Workgroups you could not use your own PC's name as a server name. However, Win95 does allow this, so it is now possible to test NetDDE on your own machine and take advantage of NetDDE's "start application on connect" capabilities.

A freeware copy of DDESHR.exe can be obtained from the CI Technologies FTP site.

WinNT Solution
The NetDDE agent which redirects calls from the local PC to the remote PC is loaded automatically when called under NT.

You must set up a NetDDE share for the DDE server (the program being controlled). This share is similar to file and print shares as it acts as an alias for a resource that other computers can use to refer to that resource. Hence, the client application, which is the program doing the controlling does not require a share to be specified.

To create NetDDE shares it is necessary to modify Registry settings. NT is equipped with a Share Manager application for this purpose. Run DDESHARE.EXE from the WinNT\System32 directory. Complete the DDE Share Properties form similar to the following.

Citect uses message based DDE so select the Static Style. Depending upon your requirements you may want to grant access to a limited set of items which in this instance would be specific variable tags. Configure this in Item Security. For security reasons you will have to make the share a Trusted Share. To do this, highlight the share and select "Trust share" and select the optoins that apply in the context of the currently logged on user. As per below:

HINTS and TIPS Under NT

• For more information on NT NetDDE Share Manager refer to Microsoft TechNet Article Q114089.
• Note that NetDDE Trusted Shares disappear after the user logs off in NT 3.51. Microsofts solution is to upgrade to NT 4.00. See Technet Article Q148129 for more details.
• If you are using netdde on an NT Domain then you may be prompted for a password each time you attempt to establish a netdde connection even though you may be logged on with a valid user account. This is true of Win95 clients connecting to an NT 3.51 or NT 4.00 DDE Server. Microsoft confirm this to be a problem and will update article Q140551 when more information becomes available.
• You may need to goto the NT User Manager and assign privileges to Users. Note that "blank" passwords are not permissable, but you will not be warned of this.
• Wild card sharenames are not supported under Windows NT. See KB Q1927. Although the NT DDE Share Manager appears to support * in the Topic Field, we have to date been unsuccessful in establishing a DDE Connection using this notation.