Specifications
RSLinx – Training Guide D - 3
Shared Topic Configuration:
With RSLinx, no user intervention is required to implement NetDDE. The only difference
from the user’s point of view is in the Application/Topic/Item string that they enter in the
client application to implement DDE communications with RSLinx (see the examples on
the next page).
But behind the scenes
, in order for a Server application on one Windows NT or 95
computer to use NetDDE to communicate with a Client application running on another
computer, a DDE share must first be created on the Server computer.
Creating a Shared Topic in Windows NT:
Share entries are required in the Windows NT registry of the computer running the RSLinx
Server for NetDDE to function. These shares must be created manually on the RSLinx
Server using the DDESHARE utility that comes with NT.
1. Select the Run menu item to display a Run dialog box.
2. Type DDESHARE.EXE in the Command Line combo box. A DDE Shares window
displays.
3. Select DDE Shares by double clicking the icon or select Shares menu item. A DDE
Shares dialog box displays.
4. Click the Add a Share... button. A DDE Share Properties dialog box is displayed.
5. In the Share Name field, enter a name of your choice to remember this NetDDE
share by. The name should be one that identifies RSLinx and the specific PLC and
data available through the RSLinx topic you wish to use.
6. Enter the Application and Topic within the Static fields. For RSLinx, the application is
RSLINX and the RSLinx topic you wish to use.
7. Check Allow start application and click the OK button to return to the DDE Share
Properties dialog box.
8. Highlight the DDE share name you just entered and click the Trust Share button to
display a Trusted Share Properties dialog box.
9. Check both the Start Application Enable and Initiate to Application Enable check
boxes.
10. Click the Set button then click the OK button to return to the DDE Shares dialog box.
Close the DDE Shares dialog box.
Note: RSLinx does not automatically create a NetDDE share entry in the NT
or Windows 95 registry for configured topics. While Windows NT
currently has the tools to create shares manually, Windows 95 does not
offer this utility. Rockwell Software is currently working on a utility to
create DDE shares in a Windows 95 machine acting as a server.