I was very happy to be able to use Arduino I2C with CoDeSys but I have instability problems !!
By the time I compiled with ide 1.8 and Arduino, with your example, it is very unstable.
The LED flashes for a while then stops to continue maybe or maybe not.
Now they will try to compile with 1.6.3 as you did, but I wonder how it is possible to have a stable according to the compiler !!
Another thing: I do not understand your last comment snippet.
So you should remove the & before sendBuffer in the Wire.write() call (Compiled with Arduino 1.6.3 on Windows 7 64bit)
With these corrections everything works fine!
Where is the '&' in the old code ?