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!

  My YouTube channel
I have to take the opportunity and start this list with my YouTube channel, which is mostly about TwinCAT 3 development. I have a TwinCAT 3 tutorial and content related to unit testing in TwinCAT there.

   Got TwinCAT
This is a Russian TwinCAT blog maintained 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’s blog
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.

  Coding Bytes TwinCAT 3
Not actually an YouTube channel (despite the icon), but rather a video resource. This is a channel with non-official information from Beckhoff members and it’s simply put an awesome resource! Very high quality content! I’ve learnt tons of stuff thanks to this channel.

  SquishyBrained YouTube channel
For anyone starting out with TwinCAT and that want an introduction I highly recommend this channel made by Evan Jensen. Evan has two series of tutorials on his channel. One general about PLC-programming in TwinCAT and a second one about motion control in TwinCAT. Evan has put a lot of effort into both series, and I highly recommend both for any newcomer to TwinCAT!

   Roald Ruiter’s Blog
Roald has some really neat tricks up his sleeve regarding TwinCAT 3 development! I highly recommend looking around at his GitHub account, as he is very passionate about TwinCAT 3 s/w development. I especially recommend you to check TcBlack.

This is an open source framework and set of open source libraries for TwinCAT 3. It’s highly maintaned and one of the best open source initiatives that are out there specifically for TwinCAT 3. The TcOpen repository has a thriving community and living discussions!

One of my biggest problems/annoyances with TwinCAT 3 is that Beckhoff refuses to publish (proper) release notes whenever they release a new version of TwinCAT or supplement. This is something I’ve discussed previously. Roald, an avid contributor to the TwinCAT community, has solved this partially by creating a repository where every TwinCAT user can contribute with any changes that they have found in new TwinCAT releases.

An excellent TwinCAT blog provided by Gerhard Barteling. Gerhard has written several very interesting posts, which of my favorite ones are the one regarding design patterns.

The TwinCAT developer Scott Whitlock maintains this great TwinCAT-blog. I highly recommend his TwinCAT3 tutorial blog posts series for any newcomer to TwinCAT.

  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!

  Oleg Mueller’s YouTube channel
Oleg has a YouTube channel and he is making some excellent videos about the new web-based TwinCAT HMI.

   Chris PLC Blog
Chris is a very active blogger and regularly posts new content on his blog. He not only has interesting stuff about TwinCAT 3/CODESYS, but also about robot programming.

   WJB Automation Blog
Wojciech Bagniewski is a software engineer and runs a blog which has some interesting content. One the blog there is an interesting series of posts about running the unity game engine together with TwinCAT3. A must read!

   Kassym Dorsel’s Blog
Kassym has a blog about mostly TwinCAT 3 development. I recommend you to check out his tests of the TwinCAT vision system!

  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!).