Text based protocol 7 chars
S - 'S' char, start byte A - '0..9', Arm address, 0 is broadcast SSS - '000..999', fixed 3 char number of servo DDD - '000..999', fixed 3 char degree \n - 'new line char 0x10'
example: 'S3001050\n' - set arm ID 3, Servo 1, 50 degrees