LinuxCNC as a PLC

Yes, you can do this. Perhaps an RPi or something similar would be appropriate?

The Udoo board has a lot of IO in an Arduino pinout. You need an ARM version of LinixCNC , and that's something of a project rather than a simple download, but it would work.

For a one-off, probably too much trouble given that an x86 PC can be <$100.

Advancedhmi is free software program for building operator screens. It's easy to use to build virtual operator screens by dragging and dropping widgets into the screen and filling up forms to attache widget variables to PLC memory. They have Modbus driver which is the most widely supported protocol in the industry.

www.advancedhmi.com
Also check this site if you would like to script your own protocol
Using AdvancedHMI's PLC drivers with C#
www.mesta-automation.com

I am interested in what you are trying to achieve. You say you want to use LinuxCNC, but no need for the UI, only ladder and HAL.

For several years (yes years on weekends) I have been trying to work with the MTConnect protocol inside the Robot Operating System (ROS) library. The MTConnect code is here: github.com/mtconnect/ros_bridge/tree/mas...s_bridge/scripts/src

and you can find instructions for the build of ROS in Eclipse on the internets.

I am close to cracking this puzzle, but I could use a second test person. I don't know (or like) Python, so that makes it tricky, I am facing some TCP/IP issues, and I know I likely will end up breaking CORS security to test what I am writing, but it sounds like this might be a solution you are looking for.

I am doing the exact thing you are speaking about , instead of classic ladder, I'm writing components. My set up is Rpi3 and a 7i90 board in spi mode. I loaded 2.8 pre on it to get the rpi driver. So far it seems to work well. I can help you get the kernel patched and lcnc loaded if you go that route. I have a second pi/ 7i90 set up that is going on my hardinge lathe , replacing a dual core amd and 5i20, curious to see how it works. Lemme know if I can help.