CODEWITHSUNDEEP
javaserial-port
Ayub
Ayub

Reputation: 599

java-simple-serial-connector read/write server

I have modified the example shown on https://code.google.com/p/java-simple-serial-connector/wiki/jSSC_examples to show read/write from java program. I can run the program, however the data I send using serialPort.writeString("HelloWorld"); does not seem to be read in the SerialPortReader event class. Could any one please point what the issue is ?

 public class SerialReaderWriter {

static SerialPort serialPort;

public static void main(String[] args) {
    serialPort = new SerialPort("COM1"); 
    try {
        serialPort.openPort();
        serialPort.setParams(9600, 8, 1, 0);
        //Preparing a mask. In a mask, we need to specify the types of events that we want to track.
        //Well, for example, we need to know what came some data, thus in the mask must have the
        //following value: MASK_RXCHAR. If we, for example, still need to know about changes in states 
        //of lines CTS and DSR, the mask has to look like this: SerialPort.MASK_RXCHAR + SerialPort.MASK_CTS + SerialPort.MASK_DSR
        int mask = SerialPort.MASK_RXCHAR;
        //Set the prepared mask
        serialPort.setEventsMask(mask);
        //Add an interface through which we will receive information about events
        serialPort.addEventListener(new SerialPortReader());

        serialPort.writeString("HelloWorld");
    }
    catch (SerialPortException ex) {
        System.out.println(ex);
    }
}

static class SerialPortReader implements SerialPortEventListener {

    public void serialEvent(SerialPortEvent event) {
        //Object type SerialPortEvent carries information about which event occurred and a value.
        //For example, if the data came a method event.getEventValue() returns us the number of bytes in the input buffer.
        System.out.println(event.getEventType());
        if(event.isRXCHAR()){
            if(event.getEventValue() == 10){
                try {
                    String data= serialPort.readString();
                    System.out.println(data);
                }
                catch (SerialPortException ex) {
                    System.out.println(ex);
                }
            }
        }
        //If the CTS line status has changed, then the method event.getEventValue() returns 1 if the line is ON and 0 if it is OFF.
        else if(event.isCTS()){
            if(event.getEventValue() == 1){
                System.out.println("CTS - ON");
            }
            else {
                System.out.println("CTS - OFF");
            }
        }
        else if(event.isDSR()){
            if(event.getEventValue() == 1){
                System.out.println("DSR - ON");
            }
            else {
                System.out.println("DSR - OFF");
            }
        }
    }
}

}

Upvotes: 2

Views: 18335

Answers (3)

sandhya murugesan
sandhya murugesan

Reputation: 114

You can't read data from the same port where you write(COM1 here). I have followed the below steps for reading and writing using JSSC.

Fake your serial port with SerialPortMonitor.

  1. Send data from COM2 from the SerialPortMonitor device installed. enter image description here

  2. Mode->Spy would show your written string "HelloWorld" and received String "OK"enter image description here

Make the below modifications and check your code:

serialPort.setFlowControlMode(SerialPort.FLOWCONTROL_RTSCTS_IN |
                                 SerialPort.FLOWCONTROL_RTSCTS_OUT);

serialPort.writeBytes("HelloWorld");//Write data to port
PortReader portReader=new PortReader(serialPort)
serialPort.addEventListener(portReader, SerialPort.MASK_RXCHAR);
int[][] eventArray=serialPort.waitEvents()
for (int i = 0; i < eventArray.length; i++) {
    if ((eventArray[i][0] > 0) ) {
    serialPort.eventListener.serialEvent(new SerialPortEvent("COM1", eventArray[i][0], eventArray[i][1])); // wait for the listener event to complete
        }
    }

The port reader class: (You were missing the Override annotation and passing in the serial port)

public class PortReader implements SerialPortEventListener{
SerialPort serialPort
public PortReader(){}
public PortReader(SerialPort serialPort){this.serialPort=serialPort}
    @Override
    public void serialEvent(SerialPortEvent event) {
    if(event.isRXCHAR() && event.getEventValue() > 0) {
            try {
                String receivedData = this.serialPort.readString(event.getEventValue());
                System.out.println("Received response: " + receivedData);
                this.serialPort.closePort();//Close serial port
            }
            catch (SerialPortException ex) {
                System.out.println("Error in receiving string from COM-port: " + ex);
                this.serialPort.closePort();//Close serial port
            }
        }
    }

}

Upvotes: 1

astral
astral

Reputation: 1

if your device doesn't require RTS/CTS flow control or you dont have a fully connected serial cable

( only RX, TX, GND)

you should switch off the data terminal ready (dtr) signal for the serial communication

add this 

serialPort.setRTS(false); 
serialPort.setDTR(false);

after 

serialPort.addEventListener(new SerialPortReader());

Upvotes: 0

onoitsjon
onoitsjon

Reputation: 16

The command

serialPort.writeString("HelloWorld");

sends the string

HelloWorld

from COM1. The SerialPortReader class that you are implementing causes COM1 to listen for the event type isRXCHAR (AKA when COM1 receives a char).

Do you have a serial cable connected to the serial port?

Unless you cross the RX and TX pins of COM1 or have a separate COM port (whose TX and RX is connected to COM1's RX and TX pins respectively), the SerialPortReader will never be activated.

Upvotes: 0

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