OK.
I know that whenever there is something above 0 in the serial port, i know that it is a sensor and that the sensor always sends 34 bytes every second. I'm not deniyng that the check could be more thorouh, check for FF wich is always the first byte from sensor and then check for 55 wich is always the second, and so on, but for simplicity, i don't think is needed, from experimentation this is what happens every time, and when it's not, it's either that the serial communication is breaking up (walking away from detection zone) or that there is no sensor being heard (-1 in the port).
Also i've been checking to see where the arduino is getting stuck and it's in the setup loop, possibly to due with the "while" check at the end of it, but i've removed that and is still hit and miss. when hit everithing works ok when a miss then nothing appears on serial1, so maybe to do with my initilization strings. Any other way sending those with more reliably?