I have a system whereby two Arduino megas communicate via Serial0 (0,1 pins). One is the master the other is the slave.
If both units are connected to the PC via USB, everything works fine. However when I connect up both units to a 12V PSU via the dc plugs and not to USB, both Arduinos no longer communicate to each other. All other code functions still work fine except receiving data. I am using the Serial. Print() function.
Any help would be appreciated.
Thanks in advance.