Signal K permission denied cannot open /dev/ttyS0

[fsarfatti]

Hi All!

I installed a GPS with gpio in Raspberry 3 with OpenPlotter v2.

When I start Signal K, have following error:
"Error: Permission denied, cannot open /dev/ttyOP_gps2"

"/dev/ttyOP_gps2" is the alias of "/dev/ttyS0"

the problem is the mode permissions in /dev/ttyS0:  crw--w---- root tty  

I can modify that with sudo chmod 0666 /dev/ttyS0 and it works, but after a seconds it return to original permissions.

I tried to modify rules in /etc/udev/rules.d, inside files 10-openplotter.rules and 99-com.rules, and adding a new file local.rules, but the problem persists


thanks in advance!!!