Modicon Modlink DDE server and Windows NT


Thread Starter

Pascal Georges

We want to use Modlink 2.1 on a PC running Windows NT4, SP5. Modlink is used as a DDE server to a National Instrument LabVIEW application. The main concern with this is that Modlink is burdening the PC, requesting 98 to 100% of the CPU time. We noticed that the problem does not exist with Windows 95/98. We tried Windows 2000 which showed the same behaviour as Windows NT4.
Adding additional RAM or disk space to the PC does not seem to help.

Is there anything we can do to let Modlink use a decent part of the CPU time with Windows NT 4 or Windows 2000? Is this linked to the fact that Modlink is a 16-bit application?

Can anyone help me ?

Pascal Georges
Test Technology Support Dept
You may wish to contact modicon tech support at 800-468-5342 if in the us, or other numbers elsewhere. I believe this is the same issue I ran into with one of my customers. The resolution to that case was that the cpu usage is not reported correctly within winNT and that the usage was closer to 10% in their actual case. The reporting was erronious but the pc did perform well anyways. Is you pc running sluggish, or are you not experiencing any performace problems and just got a scare when seeing the report of high usage?
Don't know if it can be applied to lab view or NT, but we abandoned modlink and DDE servers for 3rd party activeX drivers which are MUCH faster.

Peter Whalley


Can you explain what an ActiveX driver actually is and what protocol and API it uses for network communications. In particular how does it compare
to OPC. Is an ActiveX driver a proprietary version of OPC. Why use ActiveX rather than say OPC.


Peer Whalley
Magenta Communications Pty Ltd
Melbourne, VIC, Australia
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