Category: EtherCAT
You're just making life hard for yourself if you want a reliable solution. But if you want to go down that path good luck.
Firstly I read this:
linuxcnc.org/docs/html/man/man9/hal_parport.9.html
Then read:
github.com/LinuxCNC/linuxcnc/blob/master...rivers/hal_parport.c
That should give you an insight into the hal parallel port driver works.
Now the task would be writing a realtime driver that mimics the functions of the haL-parport driver and talks to the the ethercat hardware. Once again the limiting factor will be the latency as this will affect the base thread period and the step speed.
Personally I think a Mesa card, 7i92 would be a simple upgrade to a 2 port parallel port system, is the way to go. This is the most mature & supported option.
There are also 2 really well supported & mature projects, Remora & Linuxcnc-RIO that can be used instead of want you want to do.
BTW I have created a couple of boards to use with an FPGA that can be used with Linuxcnc-RIO that will give you about 3x17 pin ports that can be used with a chinese breakout board, 1x12 pin port a 1x6 pin port and a 1x3 pin port.
This can also run modified Mesa 7c81 firmware to either connect to an RPi4/5 or (probably not of interest to you) to a PC via EPP interface.
I'm also toying with the idea of an Ethernet interface as well, but this is just in the "what if" stages.
