Thanks for the explanations, I begin to understand which parameters are exchanged between the tnc controller and the spindle drive.
In my case here is the wiring diagram from the maintenance manual
http://i739.photobucket.com/albums/x...e/IMG_2015.jpg
IMG_2016.jpg picture by cantause - Photobucket
I can send you the original file if you give me your e-mail address, I had to take pictures as I don't have an a3 scanner, I hope that the quality is sufficient.
There is no toolchanger on this mill, it's a spindle with a QC40 nut, the power drawbar was an option. It's a bit sad, in the case of a retrofit I would have liked to build a toolchanger, there are probably very interesting things to learn in such a project!