Hi Klaus,
to my knowledge there is only one Chinese company that produces a Mach4 capable controller and they don't work at all well. AVOID LIKE THE PLAGUE!.
If you read any of my other posts you'll find I am pretty scathing of Chinese made gear so you may and probably should consider what I say with some
suspicion.
All external motion controllers require a plugin, its software that allows Mach to talk to the control board. Most control boards will work with both
Mach3 OR Mach4 if you have the right plugin.
I use an Ethernet SmoothStepper by Warp9. They make two models, the Ethernet connected ESS, and the USB connected USS. The USS works with Mach3 only,
so you want the ESS, it will works well with either Mach3 OR Mach4.
https://warp9td.com/PoKeys make several boards that are capable of Mach3 OR Mach4. The 57CNCdb25 is a single 'port' device whereas the 57CNC has over 50 IO pins. They
have a good reputation for quality and support and the 57CNC is very flexible.
https://www.poscope.com/CNCDrive make the UC100, a single 'port' device and the UC300 board with five 'ports'. They have Mach3 and Mach4 plugins. They are good quality and have
good backup. The Mach4 plugin is fairly new and not as developed as some of the others in this list.
https://www.cncdrive.com/Vital Systems make the Hicon board, very good quality with both Mach3 OR mach4 plugins. It is the most expensive one in this list but is also the most developed
and polished unit. Good backup.
http://www.vitalsystem.com/portal/index.phpPMDX have been in the business of making Mach boards for a long time and the PMDX-411 which has one 'ports' worth of IO or the PMDX-422 which has two 'ports'
worth of IO are popular but have a Mach4 only plugin. Very good quality and support.
https://www.pmdx.com/XHC is a Chinese company that make boards for Mach3 and other models for Mach4. I think they're rubbish, If you get one your on your own....a lot of Chinese
manufacturers don't bother to help you. AVOID LIKE THE PLAGUE!
http://www.machsupport.com/forum/index.php/topic,36023.0.htmlCSLabs is a Polish company that make very good boards, their Mach3 plugin is good. Their Mach4 plugin is not and for some reason they don't seem to be very interested in
fixing it, they used to be very good. They are very expensive and given the cost they should support their boards well but are not . Hard to recommend.
https://en.cs-lab.eu/Craig