通过串行端口java.net.SocketException的通信：软件导致连接中止：套接字写入错误

Question

I have written code which helps my device to communicate using serial port. But after writing some lines the code sends the exception. And i do not know why it is doing this.

The code i have written is as under:

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.SocketException;
import javax.comm.SerialPort;
import javax.comm.UnsupportedCommOperationException;
import org.dellroad.jvser.TelnetSerialPort;
import org.apache.commons.net.telnet.TelnetClient;
public class InclinometerCommunicator 
{

private static final int DEFAULT_TCP_PORT = 10001;

private static final byte ADDRESS = (byte) 0xB1;
private static final byte ENQUIRY = 5;

private static final int PACKET_LENGTH = 11;

private TelnetSerialPort port; 
public static final int BAUD_RATE = 9600;
public static final int DATA_BITS = SerialPort.DATABITS_8;
public static final int PARITY_BITS = SerialPort.PARITY_NONE;
public static final int STOP_BITS = SerialPort.STOPBITS_1;
public static final int FLOW_CONTROL = SerialPort.FLOWCONTROL_NONE;

public InclinometerCommunicator(InetAddress host) throws UnsupportedCommOperationException, SocketException, IOException {
    this(host, DEFAULT_TCP_PORT);
}

public InclinometerCommunicator(InetAddress host, int tcpPort) throws UnsupportedCommOperationException, SocketException, IOException {
    port = new TelnetSerialPort();
    port.setSerialPortParams(BAUD_RATE, DATA_BITS, STOP_BITS, PARITY_BITS);
    port.setFlowControlMode(FLOW_CONTROL);
    port.setDTR(true);
    port.setRTS(false);
    port.getTelnetClient().connect(host, tcpPort);


}

public float getAngle() throws IOException, InterruptedException 
    {
    sendFlowControl();
    Thread.sleep(100);
    sendEnquiry();
    Thread.sleep(200);
    receiveFlowControl();
    Thread.sleep(200);
    byte[] packet = readPacket();

    return parsePacket(packet);
    //return (float)1.5;
}

private void sendFlowControl() {
    port.setDTR(false);
    port.setRTS(true);
}

private void sendEnquiry() throws IOException {
    OutputStream out = port.getOutputStream();
    out.write(new byte[]{ADDRESS, ENQUIRY});
    out.flush();

}

private void receiveFlowControl() {
    port.setRTS(false);
    port.setDTR(true);
}

private byte[] readPacket() throws IOException {
    InputStream in = port.getInputStream();
    byte[] buf = new byte[PACKET_LENGTH];
    int totalRead = 0;
    int i = 0;

    while (totalRead < PACKET_LENGTH && i < 100) {
        totalRead += in.read(buf, totalRead, PACKET_LENGTH - totalRead);

        i++;
    }
    return buf;
}

private float parsePacket(byte[] packet) {
    //TODO add additional checking
    /*
    for(byte b: packet)
        System.out.print(b+" ");
    System.out.print("\n");
    */
    return (float) ((100*atoi(packet[1])) + (10*atoi(packet[2])) + atoi(packet[3]) + (.1*atoi(packet[5])) + (.01*atoi(packet[6])));
}

private int atoi(byte a) {
    return (byte) (a - '0');
}
}

And the other class is here:

import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.InetAddress;
import java.net.Socket;

public class QService {

private InclinometerCommunicator communicator;


public static void main(String[] args) {
    QService rc = new QService();
    rc.run("10.168.217.106");
}

public void run(String ip) 
{

    try 
    {

        communicator = new InclinometerCommunicator(InetAddress.getByName(ip), 9999);
    } 
    catch (Exception e) 
    {
        e.printStackTrace();
    }

    while (true) 
    {
            float angle ;

        try 
        {


            angle = communicator.getAngle();
            System.out.println("Angle:" + angle);
            Thread.sleep(1000);


        } 
        catch (Exception e) 
        {
            System.out.println("Exception"+"::"+e); // Exception coming here
            e.printStackTrace();
        }

    }
}

}

And the output is

Angle:-670.48
Angle:7118.36
Angle:367.57
Angle:7351.34
Angle:3094.42
Angle:-1599.83
Angle:527.55
Angle:7119.96
Angle:3857.8
Angle:209.53
Exception::java.net.SocketException: Software caused connection abort: socket write error
java.net.SocketException: Software caused connection abort: socket write error
at java.net.SocketOutputStream.socketWrite0(Native Method)
at java.net.SocketOutputStream.socketWrite(Unknown Source)
at java.net.SocketOutputStream.write(Unknown Source)
at java.io.BufferedOutputStream.flushBuffer(Unknown Source)
at java.io.BufferedOutputStream.flush(Unknown Source)
at org.dellroad.jvser.telnet.TelnetClient._flushOutputStream(TelnetClient.java:81)
at org.dellroad.jvser.telnet.TelnetOutputStream.flush(TelnetOutputStream.java:146)
at InclinometerCommunicator.sendEnquiry(InclinometerCommunicator.java:66)
at InclinometerCommunicator.getAngle(InclinometerCommunicator.java:48)
at QService.run(QService.java:38)
at QService.main(QService.java:14)

Answer 1

This error is originating at the network layer, not the application layer. Looks like the underlying TCP connection is getting disconnected, perhaps due to the other side closing it unexpectedly. Check the logs on the other end. A tcpdump (or Wireshark) packet trace will verify what's going on at the TCP level.