The LibNoDave-Library nowadays is much improved by a guy named "Jochen Kuehner". He also made a lot of samples to work with it.
If you want more Information you should post this question in the German PLC-Forum
www.SPS-Forum.de.
Here you could also contact Jochen Kühner for more Information.
But also there is much more Information about your code (and so on) required.