G
Guest
Has anyone successfully received serial communications from a COM port/RS232C
device? It's easy to connect and write to a serial device with Framework 2.0,
but when I try to read from the input buffer I get nothing except a timeout
exception. No matter how high you set the SerialPort.ReadTimeout property it
doesn't seem to matter. My code (using C# for Framework 2.0) looks something
like this:
use System.IO.Ports;
public static void Main (string[] args) {
/* Fully specified port params...portname and baud is the minimum to open
port. */
SerialPort sp = new SerialPort("COM1",19200,Parity.None,8,StopBits.One);
sp.Open();
sp.NewLine = "\n"; /* set the new line char for input and output so that
Write/ReadLine functions correctly interpret end of data. */
sp.ReadTimeout = 2000; /* set time out to 2 seconds. */
sp.WriteLine("SOMECMD");
/* synchronous call to read incoming data from serial port. */
string incomingData = sp.ReadLine();
sp.Close();
}
Only thing that seems to happen here is that ReadLine times out after
waiting however long you've told it to wait in the ReadTimeout property even
though I KNOW for a fact data is coming back from the serial device (verified
w/HyperTerminal and another app). Two things about the short little code
snippet is that 1) ReadLine should be wrapped in a try/catch as you will
surely get TimeoutExceptions; and 2) the reading operation should be done via
a delegate assigned to the SerialPort.ReceivedEvent event so that read/write
operations are asynchronous. Unfortunately the VS05 documentation appears to
be missing for this event so I don't have that code working just yet.
device? It's easy to connect and write to a serial device with Framework 2.0,
but when I try to read from the input buffer I get nothing except a timeout
exception. No matter how high you set the SerialPort.ReadTimeout property it
doesn't seem to matter. My code (using C# for Framework 2.0) looks something
like this:
use System.IO.Ports;
public static void Main (string[] args) {
/* Fully specified port params...portname and baud is the minimum to open
port. */
SerialPort sp = new SerialPort("COM1",19200,Parity.None,8,StopBits.One);
sp.Open();
sp.NewLine = "\n"; /* set the new line char for input and output so that
Write/ReadLine functions correctly interpret end of data. */
sp.ReadTimeout = 2000; /* set time out to 2 seconds. */
sp.WriteLine("SOMECMD");
/* synchronous call to read incoming data from serial port. */
string incomingData = sp.ReadLine();
sp.Close();
}
Only thing that seems to happen here is that ReadLine times out after
waiting however long you've told it to wait in the ReadTimeout property even
though I KNOW for a fact data is coming back from the serial device (verified
w/HyperTerminal and another app). Two things about the short little code
snippet is that 1) ReadLine should be wrapped in a try/catch as you will
surely get TimeoutExceptions; and 2) the reading operation should be done via
a delegate assigned to the SerialPort.ReceivedEvent event so that read/write
operations are asynchronous. Unfortunately the VS05 documentation appears to
be missing for this event so I don't have that code working just yet.