Hi,

thanks by sharing your schematics. 

You toke a different approach for the input protection. What  I'm used to see in plcs  PNP/NPN inputs for PLC is a voltage divider, where the lower resistor is in parallel to the optocouple led them, the phototransistor is voltage compared and the signal goes to the mcu. This is a very simple, reliable and cheap method to protect the inputs.

What I would do for a large voltage range (but not NPN/PNP compatibility, since I do not care about NPN input, since in america/europe continents we almost only use PNP anyway) would make a constant current source for each input, them feed the optocoupler.

What you did (voltage divider them compare them optocoupler) was the first time I've ever seen and I curious why you took this approach.

Greetings, Renan

Hi, looks very promising!

I've a some experience with PLCs and developing some custom boards for industrial specific tasks.  

I wish I could see more of the schematicsm, how you managed the ios.

Greetings from Brazil 

Hey, just made the GitHub page public. It has all the KiCad design files and a full schematic in the doc folder. Check it out and if you have any more questions just let me know.