There aren’t too many resources regarding development in TwinCAT, however there are a few pages/resources which I thought would be good to list here. Other than the standard Beckhoff infosys, these are the pages I’ve found. Please contact me if you know of any more resource I should add here!

Got TwinCAT
This is a russian TwinCAT blog maintaned by Voronin Nikolai. It’s updated at regular intervals with tons of interesting content! Nikolai covers both hardware and software in this blog. What I like particularly about this blog is that it covers new products/releases from Beckhoff. My russian is terribly bad, so I usually just use a google translate to English which works just fine.

Stefan Henneken
An excellent blog written by Stefan Henneken – a real expert in TwinCAT development. I particularly like that Stefan writes about object oriented programming (OOP) techniques in TwinCAT, which is something that is particularly not too much about on the web. The content is both in German and English, so in the German case Google translate comes to the rescue.

TwinCAT LinkedIn forum
This forum is the whole reason I got a LinkedIn account. As I write this, there are over 4000 members in this forum. If there is any question that you have, post it here and it will most likely be answered by a knowledgeable TwinCAT developer.

OSCAT libraries
The OSCAT libraries are open source libraries developed in accordance to the IEC61131-3 standard. They provide a total of three different libraries; OSCAT-Basic, OSCAT-Building and OSCAT-Network. I’ve so far only used the OSCAT-Basic library, which provides function blocks and functions for engineering, mathematics, string handling, time/date and much more. A great download!

IntecreLibs library
This is a open source library with utility functions for TwinCAT developed by Mark Lazarides. Mark has managed to create some really useful utility functions and doing that with some (for me) new/unknown techniques (check his usage of pragmas instance-path and reflection, quite neat!).