@Felipe_Pardo I did publish a working version of my software for the SDI-12 communication at https://github.com/robynjayqueerie/electron-sdi12-library
I have refined it a bit since then but that example works. I suggest you look at that and then we can go from there.
The Particle does support 7E1 communication but they have never brought in accessibility to things like parity errors, framing errors etc. So just using their 7E1 will not allow you to see if there are errors in the communication. I have stayed in the later versions with using 8N1 and overlaying the 7E1 characters on that, it lets me pick up parity errors. The code on github does that if 7E1 is not defined.
You can follow more of the discussion on the thread https://community.particle.io/t/sdi-12-board/29011
Let me know how you get on and I will help if I can
Great! Thanks a lot, I will be setting up the hardware and test the code in the next days.