c# - Attemping two-way serial port communication in Unity, Serial.Write() causes freeze -

i'm building arduino controller used unity game communicates on serial port. reading data sent arduino works fine, when attempting write serial port unity instantly freezes , needs shut down task manager. need getting serialport.write() work. below, i've detailed how i'm sending data arduino , reading in unity, , how attempt write data arduino doesn't work. i've got controller sending button states unity control character on screen so

c#, unity

private serialport arduinostream = new serialport("com3", 38400);       void start(){    //setup serial connection         try{             arduinostream.readbuffersize = 8192;             arduinostream.writebuffersize = 128;             arduinostream.parity = parity.none;             arduinostream.stopbits = stopbits.one;             arduinostream.open();              //arduinostream.basestream.readtimeout = 20;         } catch(exception e){             debug.log("could not open serial port: " + e.message);             useserialcontroller = false;         }      }      private void steerandacceleratewitharduino(){                    //attemp read serial data , handle         try{             string serialdata;             //attempt read serial data             serialdata = arduinostream.readline();             debug.log ("serialdata received arduino: " + serialdata);             handleserialinputdata(serialdata);           } catch(exception e){             //if there's error, disable serial controller avoid blocking on serial.read()/write()             debug.log ("serial read error: " + e.message);             useserialcontroller = false;          }            //flush serial stream         arduinostream.basestream.flush();  } 

and arduino sending data simple

c++, arduino

serial.println(buildjsonstring(keys,values)); delay(30); 

but attempt write serialport @ in unity, crashes. i'm trying write string

c#, unity

        string serialdata = "{bluescore:" + bluescore + ",redscore:" + redscore + "}";         //write serial         try{             if(arduinostream.isopen)                 arduinostream.write (serialdata);         }catch(exception e){             debug.log ("couldn't write serial port. " + e.message);           } 

on arduino i'm attempting read serial 1 char @ time, never gets far because unity crashes

c++, arduino

void receivestatesoverserial(){   string readstring;   while (serial.available()) {     delay(3);  //delay allow buffer fill      if (serial.available() >0) {       char c = serial.read();  //gets 1 byte serial buffer       readstring += c; //makes string readstring     }   }    if (readstring.length() >0) {       serial.println(readstring); //see received   }   readstring = "";  } 

has been able read , write same serialport in unity? see wrong here? appreciated