Serial port problems

From: mimisam (michikotas_at_yahoo.com)
Date: 12/27/03 

Date: 27 Dec 2003 08:37:15 -0800

hi,

I am using Win XP and writing an application to check POS devices
(printer and cash drawer).In the application I need to choose the port
which the device is connected to. If the port chosen is wrong or the
device is off power, a communication error message should be
displayed.
I am using FileOutputStream and FileInputStream to send and receive
data from the ports. When parallel port is used, I got the feedback
when the printer is off(exception caught) or the drawer status
changes. My problem is that for serial port, I can't get any feedback
at all. No exception is caught and it hangs when I try to read in data
from the COM port.
Please help me on how to get feedback from serial ports.How do i know
when the device is off?
Thanks in advance.
Below is part of my code:

private void Check(String device, String port) {
   //port="COM1" or "LPT1"
   FileOutputStream outputWriter = null;
   FileInputStream inputReader = null;
   static byte[] check = {(byte)16, (byte)4, (byte)1};
   static byte[] testprint
={(byte)29,(byte)40,(byte)65,(byte)50,(byte)48,
                            (byte)48,(byte)50};

   try{
        outputWriter = new FileOutputStream(port);
        
        if(device.equals("drawer")){
                outputWriter.write(check);
                inputReader = new FileInputStream(port);
                int input = 0;
                input = inputReader.read();
                inputReader.close();
                inputReader = null;
                if (input==18)
                        System.out.println("Drawer is opened");
                else //22
                        System.out.println("Drawer is closed");

        }
        
        else if(device.equals("printer"))
                outputWriter.write(testprint);
        
        outputWriter.close();
        outputWriter = null;

   } catch (IOException e) {
        e.printStackTrace();
                JOptionPane.showMessageDialog(null,"Communication Error");
        }

}

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