From: Subject: NetDDE for NT, Network DDE and the NetDDE Extensions Date: Tue, 2 Nov 2004 12:32:39 -0000 MIME-Version: 1.0 Content-Type: multipart/related; boundary="----=_NextPart_000_0000_01C4C0D8.0A7A9090"; type="text/html" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_0000_01C4C0D8.0A7A9090 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Content-Location: http://www.wonderware.com/support/mmi/comprehensive/kbcd/html/netdde_7.htm NetDDE for NT, Network DDE and the NetDDE = Extensions

Tech Note 4
NetDDE for NT, = Network DDE=20 and the NetDDE Extensions

All Tech Notes and KBCD documents and software are provided = "as is"=20 without warranty of any kind. See the Terms=20 of Use for more information.

Topic#: 000403
Created: February 1, 1996

Wonderware NetDDE and Microsoft Network DDE

Wonderware=AE NetDDE=99 was developed by Wonderware to extend the = Microsoft=20 Windows DDE capabilities across different networks. With NetDDE, you can = establish multiple DDE conversations between Windows, Windows NT, = Windows 95,=20 UNIX, and VMS programs that run on different computers within a network. = NetDDE=20 on Windows NT supports NetBIOS and Windows Sockets=20 (Winsock) compliant TCP/IP stack protocols.

In May 1992, Wonderware and Microsoft signed a licensing agreement = that=20 allowed Microsoft to bundle the NetBIOS version of Wonderware NetDDE = into the=20 Microsoft office products. This led to a Microsoft version of NetDDE = called=20 Network DDE. Network DDE is bundled by Microsoft with the Windows = for=20 Workgroups (WFW), Windows 95 and Windows NT operating systems.

By default, Network DDE on Windows NT comes with the Microsoft = NetBIOS=20 interface and the NetBEUI transport protocol. But, you can install a = Winsock=20 compliant TCP/IP stack (usually the Microsoft TCP/IP stack) in place of = NetBIOS=20 and still use the NetBEUI protocol.

Note on Windows NT NetDDE Services and DDE Security

With Windows NT version 3.1, the NetDDE services used to start up=20 automatically. However, with Windows NT version 3.5, the NetDDE services = do not=20 automatically start up. (The reason is Microsoft wanted Windows NT to = initiate=20 faster.) You need to configure the NetDDE services by selecting = Control=20 Panel/Services. Make sure that you set Network DDE to=20 Automatic startup and Network DDE DSDM to Manual startup, = because=20 it is started automatically by the Network DDE service.

You also need to configure the DDE Security if you will have a server = on=20 Windows NT that provides data to a DDE client on another node. For more=20 information, see Configuring=20 DDE Security for Windows and Windows NT.

Wonderware NetDDE Extensions for Windows NT

The Wonderware NetDDE Extensions for Windows NT is an option = (not a=20 requirement) that allows a Windows NT computer to communicate with = another=20 computer using TCP/IP.

When the NetDDE extensions are installed on a Windows NT computer, = they will:=20 1) modify the Windows NT NETDDE.EXE file so that the default queue size = is=20 increased from 20 to 1000; 2) add a GUI for DDE Share Security = Management; and=20 3) add TCP/IP support through Winsock.

To avoid having the NetDDE Services hang on startup, you must add = your=20 computer node name in the HOSTS file. That is, modify the file=20 \WINNT35\SYSTEM32\DRIVERS\ETC\HOSTS and add the IP address and node name = of your=20 Windows NT node.

Note You must have TCP/IP configured on your = computer=20 before you install version 1.3a of the NetDDE extensions. (Version 1.3b = corrects=20 this problem.) If you install the NetDDE extensions before TCP/IP is = configured,=20 then you will get network drive errors or service errors. The reason is = the=20 installation program cannot check to see if TCP/IP is installed and it = goes=20 ahead and changes the System Registry. Thus, if you do not have TCP/IP=20 installed, errors will result because the System Registry has changed. = (See Uninstalling=20 NetDDE Extensions for Windows NT for more information.)

Windows NT NetDDE Communication Requirements

The following two sections describe the requirements for NetDDE = communication=20 using Windows NT, both with NetBIOS and with TCP/IP:

Windows NT and NetBIOS

No setup is necessary to allow Windows NT to communicate using = NetBIOS. This=20 is because Microsoft Network DDE is built into the Windows NT operating = system.=20 You do not need to install the Wonderware NetDDE Extensions for Windows = NT on=20 the Windows NT node to communicate using NetBIOS.

The Windows NT node can communicate using NetBIOS to any other = platform that=20 is running NetDDE and has the NetBIOS interface configured. Currently, = the other=20 platforms that support NetDDE communication with NetBIOS are Windows = 3.1,=20 Windows for Workgroups, and Windows 95.

Note To communicate NetBIOS between a Windows NT = node and a=20 Windows 3.1 node, you must install NetBIOS and Wonderware NetDDE for = Windows=20 (release 1.3 or later) on the Windows 3.1 node. (Release 1.2 and earlier = of=20 Wonderware NetDDE for Windows did not have the security features that = are=20 required by Windows NT.)

Windows NT and TCP/IP

To set up the Windows NT node to communicate using TCP/IP, you must = install=20 the Wonderware NetDDE Extensions for Windows NT and configure = TCP/IP on=20 the Windows NT node. This must be done on both Windows NT nodes if you = are=20 communicating between two Windows NT nodes.

The Windows NT node can communicate using TCP/IP to any other = platform that=20 is running NetDDE and has a supported TCP/IP stack. Currently, the other = platforms that support NetDDE communication with TCP/IP are Windows = 3.1,=20 Windows for Workgroups, Windows 95, and a variety of = UNIX=20 and VMS platforms. For a current list of NetDDE platforms and = their=20 supported TCP/IP stacks, see Matrix=20 of Supported Network Software for NetDDE.

Note There is a current limitation where a DDE = client on a=20 UNIX or VMS computer cannot communicate directly to a I/O Server on a = Windows NT=20 or WFW computer that has password protection. This is because Wonderware = has not=20 yet implemented NT-type security in their NetDDE for UNIX and VMS. For a = workaround, see Connecting=20 a DDE Client on VAX or UNIX to a I/O Server on NT.

D. Ujifusa

The Tech = Note is=20 published occasionally by Wonderware Technical Support. Editors: Sabrina = Abercromby and Kelly Hauser; Publisher: Wonderware Corporation, 100 = Technology=20 Drive, Irvine CA 92618. There is also technical information on our = software=20 products at www.wonderware.com/support/mmi, our WonderFax = fax-on-demand=20 system at (949) 450-5050, and the Comprehensive Support Knowledge Base.

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