arduino - C# SerialPort communication protocol -

i did write small c# app reads com port series of numbers sent arduino board.

question:

if arduino sends single value every 500ms c# program reads single value every 1s doesn't c# left behind arduino? if true, data sent arduino stored in buffer or discarded?

[edit]

bellow code use read com

---

system.windows.forms.timer tcom; ...  tcom.interval = 1000; tcom.tick += new system.eventhandler(this.timer1_tick); ...  serialport port = new serialport(); port.portname = defaultportname; port.baudrate = 9600;  port.open(); .....  private void timer1_tick(object sender, eventargs e) {     log("time read com");      //read string serial port     string l;     if ((l = port.readline()) != null)     {     ......      }  } 

serial port communications require flow control. way transmitter know receiver ready receive data. overlooked, in arduino projects. tends work out okay, serial ports slow , modern machines fast compared kind of machines first started using serial ports.

but clearly, in scenario going go bang! after while. arduino cause buffer overflow condition when receive buffer in pc fills capacity. , causes irretrievable loss of data. listening notification of condition else that's skipped, must register event handler serialport.errorreceived event. you'd expect serialerror.overrun notification in case. there's no clean way recover condition, full protocol reset required.

there 2 basic ways implement flow control on serial ports avoid error. common 1 use hardware handshaking, using rts (request send) , cts (clear send) signals. provided handshake.requesttosend. pc automatically turn rts signal off when receive buffer gets full. arduino must pay attention cts signal , not send when off.

the second way software handshaking, receiver sends special byte indicate whether ready receive data. provided handshake.xonxoff, uses standard control characters xon (ctrl+q) , xoff (ctrl+s). suitable when communication protocol doesn't otherwise use these control codes in data. in other words, when transmit text instead of binary data.

the third way different approach, common well, make device ever send when pc asks it. master-slave protocol. having enough room in receive buffer response easy guarantee. specify specific commands in protocol, commands pc sends query specific data item.