For Network DDE to function, NetDDE.EXE needs to be installed and running on both machines before attempting to conduct a Network DDE conversation. NetDDE.exe is a Windows Service system file that is used to communicate the shared dynamic data exchange used by Network DDE. It has no graphical user interface (it runs as a background Windows service).
It is necessary to initiate the automatic activation of Network DDE Services, or manually run NetDDE.EXE on both machines before attempting connection.
To manually start Network DDE services:
To automatically start the Network DDE Services on machine startup:
To verify that the NetDDE Services are running:
Note: If you are using only the Microsoft Client Service for NetWare Networks, the NW IPX/SPX/NetBIOS compatible protocol needs to be enabled for NetDDE.exe to load.
To test that Network DDE is operational between two machines on the same network
Microsoft Windows ships with a network DDE
application called Chat. It is installed in the
Note: If Chat is not already running on the other computer, it times-out and states that the other computer didn't answer. If however, the other computer is already running Chat, it will keep dialling until answered.
Once a Chat conversation is established, it proves that both machines are properly set-up and capable of handling network DDE conversations. You can view the share properties for Chat$ by using the DDEShares.exe application as described in Setting up network DDE shares.
You don't have to run Chat to use Network DDE with CitectSCADA. This Network DDE test only uses Chat as an example to confirm Network DDE functionality between two machines. Once you have established that Network DDE is functional, close the Chat windows, create the Network DDE Trusted Share for your Network DDE server application, and connect to the share using Network DDE. See Connecting to a network DDE shared application.