JSSC does not send bytes. What could be the problem?

Question

Java

I wrote a simple class - a test, just to look and almost immediately a problem arose.
1) If you do not prescribe a port handler. Everything is working. Bytes are sent.
2) If you register a port handler. There is a reception of bytes and it works stably, but sending bytes is no longer there.
The code:

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.StandardSocketOptions;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.channels.spi.SelectorProvider;
import java.util.Iterator;
import java.util.concurrent.TimeUnit;

import jssc.SerialPort;
import jssc.SerialPortEvent;
import jssc.SerialPortEventListener;
import jssc.SerialPortException;



public class Main  implements SerialPortEventListener{
  
  public static SerialPort serialPort;
  
  public static void setAllParams () throws SerialPortException {
    System.out.println("Serial Port started!");
    serialPort = new SerialPort ("COM7");
    System.out.println(serialPort.openPort() ? "Port is open" : "Error of openning port!");
    System.out.println (serialPort.setParams(9600, 8, 1, 0) 
        ? "Set params is succeful!" : " Set params false");
    
    System.out.println(serialPort.setFlowControlMode(SerialPort.FLOWCONTROL_RTSCTS_IN | SerialPort.FLOWCONTROL_RTSCTS_OUT)
        ? "set flow control mode is succeful!" : "set flow control mode fail!");
    
    
    serialPort.addEventListener(new Main (), SerialPort.MASK_RXCHAR);
    
  
  }
  
  

  public static void ShowBits (byte b) {
    for (int i=0; i!=8; i++) {
      if ((b & 0x80) == 0x80)
        System.out.print("1");
      else 
        System.out.print("0");
      b<<=1;
    }
    
    System.out.println();
  }
  
  

  public static void main (String... string) throws SerialPortException{
    int counter = 0;
    setAllParams();
    
    
    while (true) {
      try (ServerSocket server = new ServerSocket (9091)){
        
        System.out.println("Ожидание подключения клиента к серверу");
        Socket client = server.accept();
        System.out.println("Клиент подключен!");
        
        DataOutputStream out = new DataOutputStream(client.getOutputStream());
        DataInputStream in = new DataInputStream (client.getInputStream());
        
        byte buffer [] = new byte[7];
      
        int HashCode = in.readInt();
        System.out.println("HashCode: " + HashCode);
        
        if (HashCode == -1871195855) {
          out.writeBoolean(false);
          out.writeUTF("Counter of msg #" + counter++);
        } else {
          out.writeBoolean(true);
          out.writeUTF("Отказано!");
        }
        
        
        
        int size = in.readInt();
        
        in.readFully(buffer, 0, size);
        
        
        System.out.print ("ШИМ №1: ");
        ShowBits(buffer[0]);
        System.out.print ("ШИМ №2: ");
        ShowBits(buffer[1]);
        System.out.print ("ШИМ №3: ");
        ShowBits(buffer[2]);
        System.out.print ("Статус реле: ");
        ShowBits(buffer[3]);
        System.out.print ("Секунды: ");
        ShowBits(buffer[4]);
        System.out.print ("Минуты: ");
        ShowBits(buffer[5]);
        System.out.print ("Часы: ");
        ShowBits(buffer[6]);
        
        serialPort.writeBytes(buffer);
        
        //com.write(buffer);
        
        
        
        out.close();
        in.close();
        client.close();
        server.close();
        
        
        
      } catch (IOException ex) {
        System.out.println("Error!");
      }
    }
    
  }


  @Override
  public void serialEvent(SerialPortEvent event) {
    if (event.isRXCHAR() && event.getEventValue() > 0) {
      try {
        byte [] temp = serialPort.readBytes(2);
        byte cells = (byte) (temp[0] & 0x0F);
        temp[1] = (byte) (temp[1] << 4);
        temp[0] = (byte) ((temp[0] >> 4) & 0x0F);
        float temperature = (int) (temp[1] | temp[0]);
        
        switch(cells){
        case 0x00: temperature += 0.0; break;
        case 0x01: temperature += 0.0625; break;
        case 0x02: temperature += 0.1250; break;
        case 0x03: temperature += 0.1875; break;
        case 0x04: temperature += 0.2500; break;
        case 0x05: temperature += 0.3125; break;
        case 0x06: temperature += 0.3750; break;
        case 0x07: temperature += 0.4375; break;
        case 0x08: temperature += 0.5; break;
        case 0x09: temperature += 0.5625; break;
        case 0x0A: temperature += 0.6250; break;
        case 0x0B: temperature += 0.6875; break;
        case 0x0C: temperature += 0.7500; break;
        case 0x0D: temperature += 0.8125; break;
        case 0x0E: temperature += 0.8750; break;
        case 0x0F: temperature += 0.9375; break;
        }
        
        System.out.println(temperature);
        
        
      }catch (SerialPortException ex) {
        ex.printStackTrace();
      }
    }
  }

}

Answer 1

Issue resolved. If suddenly someone needs it.

System.out.println (serialPort.setParams(9600, 8, 1, 0, true, true) 
        ? "Set params is succeful!" : " Set params false");
    
    System.out.println(serialPort.setFlowControlMode(SerialPort.FLOWCONTROL_NONE)
        ? "set flow control mode is succeful!" : "set flow control mode fail!");
    
    
    serialPort.addEventListener(new Main (), SerialPort.MASK_RXCHAR);