Other ways to interface with LinuxCNC

According to your other posts in the link, you got the BTS7960 to work nicely with Mesa cards, right? Is there also an example of an Ethernet Mesa card that will work for this? I am not a fan of the parallel port in general and would like to move away from it, since most PCs (even older ones) don't even have it anymore and Ethernet is a lot more future proof.

My machine currently has 3 axes, but I would like to have at least the possibility for 4 servo axes and a spindle, as well as some digital I/O and MPG.

If you’re a DIY guy have a look at Litehm2 project. I’m from Australia and the FPGA board was about $35 delivered. Uses the same drivers as a Mesa card. Has the same functionality as a Mesa card.
In saying all that from a “plug and play” perspective the Mesa cards are very very good value. Especially when you start costing what is takes to do voltage translation and the like.

Yeah, you're right on that one mate,especially the ones stack side by side like the ones Mesa uses. They are aren't that many suppliers for them.

Your idea reminds me a lot of the Klipper projekt in the 3D Printing Space. Do you know about it?

With Klipper the calculation is also done by a more potent CPU, such as on a Pi, then Data is send to an Arduino via USB, which then executes it.