Subject:
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Java program question
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Newsgroups:
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lugnet.robotics
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Date:
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Sun, 25 Aug 2002 22:33:56 GMT
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Original-From:
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Catherine Turner <cturne@essex.ac.uk=spamless=>
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Viewed:
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648 times
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Hi,
I've got the book "Programming Lego Mindstorms With Java" and have run the
program SimpleWriteRead from chapter 4.
When I run it I get this:
sending 'alive' message... (7 bytes) 55 ff 0 10 ef 10 ef
read response to 'alive' message... (7 bytes)55 ff 0 ef 10 ef 10
sending 'beep' message... (9 bytes) 55 ff 0 51 ae 5 fa 56 a9
Interactive Session Ended
So I don't get a read response to beep message and am wondering why. Does
anyone have any ideas? The code is below...
import java.io.*;
import java.util.*;
import javax.comm.*;
import rcx.comm.USBPort;
import rcx.comm.USBPortFactory;
/**
* Simple Java Communications API Test Program:
*
* This is a simple example of writing and reading from a comm port.
*
* Additionally it will illustrate the following:
* - Discovering all available serial ports and using the first one
* (unless one is specified on the command line)
* - How to use the USB port add-on on to the Java Communcations API
* using the rcx.comm package.
* (requires a specific port name on the command line e.g. LEGOTOWER1 )
*/
public class SimpleWriteRead {
// statics to allow use in main() which is static
static Enumeration portList;
static CommPortIdentifier portId;
static boolean useUSB;
static SerialPort serialPort;
static USBPort usbPort;
static OutputStream outputStream;
static InputStream inputStream;
// alive msg
static byte[] testArray1={(byte)0x55,(byte)0xff,(byte)0x0,
(byte)0x10,(byte)0xef,(byte)0x10,(byte)0xef};
// beep msg
static byte[] testArray2={(byte)0x55,(byte)0xff,(byte)0x00,
(byte)0x51,(byte)0xae,(byte)0x05,(byte)0xfa,(byte)0x56,(byte)0xa9};
public static void main(String[] args) {
useUSB = false;
String portName = "";
int numBytes;
int numread;
// first, are we using usb or serial?
if(args.length > 0) {
portName = args[0];
if(portName.startsWith("LEGO"))
useUSB = true;
}
if(!useUSB)
{
// FIND SERIAL PORT (unless specified):
if(portName.length()<1) {
// get all avail serial ports -see this method at bottom
Vector ports = getAvailableSerialPorts();
if(ports.size()==0) {
System.out.print("no available serial ports found - ");
System.out.println("check for conflict with another
app");
return;
} else {
System.out.println("found "+ports.size()+ " avail serial
ports");
}
portName = (String)ports.firstElement();
System.out.println("using first available port:
"+portName );
}
try {
portId = CommPortIdentifier.getPortIdentifier(portName);
} catch (NoSuchPortException e) {
System.err.println("Error: no such port "+portName);
return;
}
// SETUP SERIAL PORT:
try {
serialPort = (SerialPort)portId.open("SimpleWriteRead",
1000);
} catch (PortInUseException e) {
System.out.println("port already in use");
return;
}
try {
serialPort.setSerialPortParams(2400,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_ODD);
serialPort.enableReceiveTimeout(30);
serialPort.enableReceiveThreshold(14);
} catch (UnsupportedCommOperationException e) {
e.printStackTrace();
}
try {
outputStream = serialPort.getOutputStream();
inputStream = serialPort.getInputStream();
} catch (IOException e) {
e.printStackTrace();
}
}
else // SETUP USB PORT:
{
usbPort = USBPortFactory.getUSBPort();
try {
if(usbPort.open(portName)<0) {
System.err.println("USB port error: is tower plugged
in?");
return;
}
outputStream = usbPort.getOutputStream();
inputStream = usbPort.getInputStream();
} catch(IOException e) {
e.printStackTrace();
}
}
// now write and read (same way for both types of ports)
try {
// write a message out:
System.out.println("sending 'alive' message... ("
+testArray1.length+" bytes) "
+ArrayToString(testArray1,testArray1.length));
outputStream.write(testArray1); //alive msg
byte[] readBuffer = new byte[30];
numBytes=1; numread=0;
// read a message in:
while (numBytes>0) {
numBytes = inputStream.read(readBuffer,0,30);
if(numBytes>0)
System.out.println("read response to 'alive' message...
("
+numBytes+" bytes)"
+ArrayToString(readBuffer,numBytes));
numread+=numBytes;
}
if(!useUSB) {
// note: serial port tower echoes commands
if(numread<14) {
System.err.println("Error: is the RCX on?");
return;
} else if(numread<1) {
System.err.println("serial port error: is tower plugged
in?");
return;
}
} else {
if(numread<1) {
System.err.println("Error: is the RCX on?");
return;
}
}
System.out.println("sending 'beep' message... ("
+testArray2.length+" bytes) "
+ArrayToString(testArray2,testArray2.length));
outputStream.write(testArray2); //beep msg
numBytes=1; numread=0;
while (numBytes>0) {
//msg response
numBytes = inputStream.read(readBuffer,0,30);
if(numBytes>0)
System.out.println("read response to 'beep' message... ("
+numBytes+" bytes) "
+ArrayToString(readBuffer,numBytes));
numread+=numBytes;
}
// the following could be one call using a interface
if(!useUSB)
serialPort.close();
else
usbPort.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public static Vector getAvailableSerialPorts() {
CommPortIdentifier pId=null;
SerialPort sPort=null;
Enumeration pList=null;
boolean foundport=false;
pList = CommPortIdentifier.getPortIdentifiers();
String port=null;
Vector ports=new Vector();
if(!pList.hasMoreElements()) {
System.err.print("warning: no ports found - ");
System.err.println("make sure javax.comm.properties file is
found");
return ports;
}
while (pList.hasMoreElements()) {
pId = (CommPortIdentifier) pList.nextElement();
if (pId.getPortType() == CommPortIdentifier.PORT_SERIAL) {
foundport=true;
try {
sPort = (SerialPort)pId.open("serialport", 1000);
} catch (PortInUseException e) {
foundport=false;
} finally {
if(sPort!=null) {
try { sPort.close(); } catch(Exception e) {}
}
if(foundport) {
ports.add(pId.getName());
}
}
}
}
return ports;
}
public static String ArrayToString(byte[] message, int length) {
StringBuffer strbuffer = new StringBuffer();
int abyte = 0;
for(int loop = 0; loop < length; loop++) {
abyte = (int) message[loop];
if (abyte < 0) abyte += 256;
strbuffer.append(Integer.toHexString(abyte) + " ");
}
return strbuffer.toString();
}
}
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Message has 1 Reply:
 | | Re: Java program question
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| Could you give us details about this book? Who's the author? Seems it's a new one 'cause I never heard about it... or I missed it. Thanx. Wap "Catherine Turner" <lego-robotics@crynwr.com> a écrit dans le message de news: (...) (22 years ago, 26-Aug-02, to lugnet.robotics)
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