Sorry, but the PMDX-426 project was put on hold because we found USB to work well.
USB is not quite as resistant to noise as Ethernet, but latency and speed are not
issues with Mach4. There can be issues if you plug in a large USB storage device
and Windows goes away while it caches directories, but this problem affects any
system, including Ethernet ones, because it is related to Windows behavior not to
the communications between Mach4 and the motion device.
All of our SmartBOBs employ common mode noise filtering on the USB port, and the
PMDX-424 (and other products being considered) employ electrical isolation to
break potential ground loops between the machine controller and the host PC.
For table top machines, and many larger machines things work well without
ground loop problems, but for industrial machines we do recommend using a
controller with isolation.
Twisted pair Ethernet (10BaseT) uses transformers for electrical isolation and
this prevents ground loops.
We chose to continue with USB because we feel that it works well for us and
because USB configuration is dead simple. Ethernet and IP addressing is normally
simple except when it isn't, then there is hell to pay in doing tech support for it.