Converting an old DMU 50, where to start?

I am totally lost! I acquired an old DMU 50 mill, servo driven with Simodrive 611 servo drivers.

What hardware do I need to convert it to LinuxCNC? I have been looking at the mesa stuff, and it looks good and at a really good price, but I have no idea what I need. This has probably been discussed a million times before, but I just cant get my head around it...
The mill now has 3 controlled axis, and 2 manually controlled axis. I would want to have the ability to later add a stepper to at least on of the manual axisis and a rotary chuck for A-axis. 
I did build my own diy cnc mill some 10-15 years ago, and have all kinds of electrical and programming knowledge. 
So, can someone lay out a setup diagram for the mesa hardware I need... I know it starts with the PC --- and ends with the Simodrive 611 drivers. But all the options on how to make the PC communicate with the 611´s is a total jungle to me... 
From my experience when I built the diy cnc, it was like PC--->Breakout board (serial connected)---> stepper drivers ----> stepper motors. 
But It seems that the servo controling is a bit more complicated. So I am reaching out to you, fellow CNC enthusiastics for som tips and tricks
 

siemens 611 uses profibus most likely. it is not compatible with linuxcnc. you will need to replace the drives, and probably the motors as well.

take a picture of the label and connections on the drive, and also the motors.

Servo drives don't have to be more complicated then a stepper system and often many servo systems can take the same step/dir signals that a stepper system would take. That being said you may run into proprietary equipment when doing a retrofit that requires you to replace almost all of the components.

What year is the mill? What is wrong with the original control? Before you start making purchases you should get a really good grasp of what all the machine can do and how you want to control it. This can help to make decisions for purchases.

Send some pictures of the mill and the various drives and other components that it has.

siemens is proprietary profibus unfortunately. also very integrated, meaning the spindle drive will also not work as its part of the same system.

assuming nothing is broken, you'd do well selling off the old motor and drive kit and buying new ones. possibly breaking even as the old kit can be worth thousands.

the motors are big though, 2kw-3kw range, and the spindle will be 8-10kw. so not simplistic to replace.

Hello,

if this dmu has not an Sinumeric Control, there is an chance that this simodrives are with an analog io board. (Heidenhain or DMG manual mill control)
can you post a picure of the drive system, and the type plates.

if they have Profibus interface, the only option to keep them would be to interface them by ethercat with an profibus master card. But this needs electronics and plc experience or the will to learn this stuff.....

very early dmu 50 m might have the heidenhain control, true.
the other models used 810d or 840d.

buy yeah, were just guessing til we see pics.