Quote Originally Posted by dacb View Post
This is interesting. So if you don't define it you get a build error or a runtime error?
No, it compiles fine and runs fine except it performs a G28 properly, including raising the Z probe at the finish and then does nothing when it should be starting the G29 routine. I had this same issue when setting up ABL a little over a month ago and found the answer in a thread where someone else had the same issue. He uncommented that line and everything worked from then on. I had the same behavior and the same fix worked for me also. I haven't altered any file other than the few changes required in your fork in the configuration.h and the issue was there again. I had done hours of searching over a month ago to find a solution, so applied the same solution and had the same positive result with G29 running normally. I had assumed this must be a common issue, but from Abu's reply I'm guessing this is not common at all. The only changes I made that may not have been standard in the configuration is changing travel limits after homing #define Z_MAX_POS 250 (your build had a value of 235) and commented out Z_SAFE_HOMING.

I have included my configuration.h if you want to look at it.

Configuration.h