I made a Java program that runs on a computer with two RS-232 ports.
It works pretty good. I connected two devices that communicate with each other through RS-232. I put the computer between the cable.
You can see everything getting send on a terminal window.
But after a random amount of time one device stops responding to queries.
Normally device 1 sends query 1 and the device responds.
But after some time the device starts sending query 2 and device 2 doesn't respond anymore.
Here is a capture:
- First column: COM port id
- Second column: decimal presentation of the character
- Third column: visualization of characters
Why is this not working? I'm planning on making the terminal program open source in the future.
EDIT: I didn't post any code because the code works. It only stops working after 5 min - 1 hour.
Here is the connection code:
CommPortIdentifier portIdentifier;
portIdentifier = CommPortIdentifier.getPortIdentifier("COM1");
InputStream inCom1;
InputStream inCom2;
if (portIdentifier.isCurrentlyOwned()) {
addError("COM1 in use!, please restart");
}
else {
SerialPort serialPort = (SerialPort) portIdentifier.open("Main", 2000);
//19200 8n1
serialPort.setSerialPortParams(19200, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
// CTS/RTS handshaking
serialPort.setFlowControlMode(SerialPort.FLOWCONTROL_RTSCTS_IN | SerialPort.FLOWCONTROL_RTSCTS_OUT);
//Set sender
Com1Sender.setWriterStream(serialPort.getOutputStream());
//Set receiver
// new com1_receive(serialPort.getInputStream()).start();
inCom1 = serialPort.getInputStream();
portIdentifier = CommPortIdentifier.getPortIdentifier("COM2");
if (portIdentifier.isCurrentlyOwned()) {
addError("COM2 in use!, please restart");
}
else {
serialPort = (SerialPort) portIdentifier.open("Main2", 2001);
//19200 8n1
serialPort.setSerialPortParams(19200, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
// CTS/RTS handshaking
serialPort.setFlowControlMode(SerialPort.FLOWCONTROL_RTSCTS_IN | SerialPort.FLOWCONTROL_RTSCTS_OUT);
//Set sender
Com2Sender.setWriterStream(serialPort.getOutputStream());
//set receiver
// new com2_receive(serialPort.getInputStream()).start();
inCom2 = serialPort.getInputStream();
new Receiver(inCom1, inCom2).start();
}
}
This is the receiver:
public class Receiver extends Thread {
InputStream inCom1;
InputStream inCom2;
public Receiver(InputStream inCom1, InputStream inCom2) {
this.inCom1 = inCom1;
this.inCom2 = inCom2;
}
@Override
public void run() {
try {
int b1;
int b2;
while (true) {
// if stream is not bound in.read() method returns -1
//dect
while ((b1 = inCom1.read()) != -1) {
//Send trough to COM2
Com2Sender.send(new byte[]{(byte) b1});
Main.addText(Integer.toString(b1), true);
}
//televic
while ((b2 = inCom2.read()) != -1) {
//Send trough to COM2
Com1Sender.send(new byte[]{(byte) b2});
Main.addText(Integer.toString(b2), false);
MessageExtractor.add(b2);
}
// Wait 10 ms when stream is broken and check again.
sleep(10);
}
} catch (Exception e) {
Main.addError(e.getMessage());
}
}
}
This is one of the senders:
public class Com1Sender {
static OutputStream out;
public static void setWriterStream(OutputStream out) {
Com1Sender.out = out;
}
public static void send(byte[] bytes) {
try {
// Sending through serial port is simply writing into OutputStream.
out.write(bytes);
out.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
public static void send(int letter) {
try {
Main.addText(Character.toString((char)letter), false);
// Sending through serial port is simply writing into OutputStream.
out.write(new byte[]{(byte)letter});
out.flush();
} catch (IOException e) {
e.printStackTrace();
}
}
}
