Rxtx - User contributions [en]

Installation

Sdhip — Mon, 02 Apr 2007 15:48:30 GMT

Sdhip: /* I Can Not Open the Port. */

<pre>
/*-------------------------------------------------------------------------
| rxtx is a native interface to serial ports in Java.
| Copyright 1997-2004 by Trent Jarvi taj@www.linux.org.uk
|
| This library is free software; you can redistribute it and/or
| modify it under the terms of the GNU Library General Public
| License as published by the Free Software Foundation; either
| version 2 of the License, or (at your option) any later version.
|
| This library is distributed in the hope that it will be useful,
| but WITHOUT ANY WARRANTY; without even the implied warranty of
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
| Library General Public License for more details.
|
| You should have received a copy of the GNU Library General Public
| License along with this library; if not, write to the Free
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
--------------------------------------------------------------------------*/
</pre>
This is the INSTALL file for RXTX. Thu Jul 7 19:46:26 EDT 2005

If, while following the instructions, you find this file unclear or incorrect
please make a note and email the details to taj@www.linux.org.uk.

A note about rxtx 2.1:

rxtx 2.1 replaces the entire CommAPI. Every effort is made to conform to
CommAPI but out of respect for our friends at Sun the package name of 2.1 has
been moved to gnu.io. A script is offered in contrib/ChangePackage.sh that
will switch source tree's between javax.comm and gnu.io.

See Sun's CommAPI license for more details on why this decision was made.

If you would like to use javax.comm, use rxtx 1.4 with Sun's CommAPI.
</code>

A note on Mac OS X:

Go to the MacOSX file for install instructions.

-------------------------------------------------------------------------------
=== INSTALL INSTRUCTIONS IN OTHER LANGUAGES ===
==== A. Japanese ====

Instructions are available in Japanese at

The instructions are fairly old but should help.

http://www.geocities.co.jp/Technopolis/4789/settei.htm#id1
Thanks to Masayuki "Tencho" Yamashita <tencho@venus.kanazawa-it.ac.jp>
home page http://www.geocities.co.jp/Technopolis/4789/

A copy of these install instructions is provided in
install-japanese.html

We will gladly include instructions in any language provided. Tencho
was the first to contribute instructions in another language.

=== BUILDING COMMAPI SUPPORT ===

The following is concerned with building and installing commapi
support with Sun's CommAPI package. A full stand alone version of
rxtx is in the CVS archive for interested developers.

==== Quick Install ====

The following packages are used to build rxtx:

autoconf-2.59
automake-1.9.5
libtool-1.5.18
gnu make-3.79.1 On some systems like FreeBSD this is
called gmake
jdk 1.3 or newer

With the packages installed, proceed to build and install rxtx.

<pre>
$ tar -xzvf rxtx-2.1.tar.gz
$ cd rxtx-2.1
$ ./configure (follow the instructions)
$ make install (gmake if your system uses that convention)
Read "R. How can I use Lock Files with rxtx?"
</pre>
One catch that has showed up... you cannot have spaces in the path.
for instance: /home/jarvi/test build/rxtx/... will cause problems.
----^
If that does not work or you do not want a script messing with the
system, read on..

==== Uninstalling Sun's comm.jar ====

Sun's comm.jar is not required. It is a valid option on
some platforms. IT WILL CREATE CHAOS if you have it installed
while trying to build rxtx 2.1.

http://java.sun.com/products/javacomm/index.html

==== Installing javax.comm.properties. ====

javax.comm.properties is not currently required by rxtx-2.1

==== Add RXTXcomm.jar to your CLASSPATH. ====

jdk-1.1:

make sure /usr/local/java/lib/RXTXcomm.jar is in your
CLASSPATH. If you want to use apps that require
RXTXcomm.jar.

in bash:

$ export CLASSPATH=${CLASSPATH}:/usr/local/java/lib/RXTXcomm.jar:.

jdk-1.2 and newer:

No changes are needed.

==== Build and Install the jar. ====

configure configure supports build directories.
configure requires javac in its path or
JAVA_HOME set to grab some java system
properties.
make to build RXTXcomm.jar and the libraries
make install to place the jar and libraries in the correct
location

You may select the JDK you wish to build with using $JAVA_HOME
For example:
export JAVA_HOME=/usr/local/java
Otherwise, configure grabs the JDK from your PATH.

==== Where did everything end up? ====

Lets assume the top java directory is /usr/local/java

jdk-1.2 the files go in
<pre>
/usr/local/java/jre/lib/ext/RXTXcomm.jar
/usr/local/java/jre/lib/$(ARCH)/librxtxSerial.so.
/usr/local/java/jre/lib/$(ARCH)/librxtxParallel.so.
/usr/local/java/jre/lib/$(ARCH)/lib/...

jdk-1.1.* the files go in

/usr/local/java/lib/RXTXcomm.jar
/usr/lib/librxtxSerial.so.
/usr/lib/librxtxParallel.so.
/usr/lib/...

The librxtxSerial.so librxtxParallel.so are placed in
/usr/lib so people don't have to change with their
LD_LIBRARY_PATH.
</pre>

==== Compiling for Win32 support ====

Get the Sun CommAPI if you want a plug-in solution. The code
is provided for people that may have demanding needs and coding
ability.

There is only serial port code at this time.

Three ways of compiling win32 libraries are offered:

mingw32 tools in DOS
lcc tools in DOS
cross-compiling from Linux
===== mingw32 tools in DOS =====

Install mingw32 http://www.mingw.org
Install a jdk http://java.sun.com/j2se
Make sure the ming32\bin and jdk\bin directories are in your
path.
In the rxtx top directory to the following:
mkdir build
copy Makefile.mingw32 build\Makefile
cd build
edit the Makefile and make sure the directories are correct.
execute the following:
make
make install

===== lcc tools in DOS =====

Install a jdk http://java.sun.com/j2se
Install lcc http://www.cs.virginia.edu/~lcc-win32/

A make file (Makefile.lcc) for compiling rxtx with lcc
contributed by Valentin Pavlov

You will need a config.h file in the src directory. Other
builds usually generate them automatically. The following
should work.

#define HAVE_FCNTL_H
#define HAVE_SIGNAL_H
#undef HAVE_SYS_FCNTL_H
#undef HAVE_SYS_FILE_H
#undef HAVE_SYS_SIGNAL_H
#undef HAVE_TERMIOS_H
#undef HAVE_SYS_TIME_H

if you know how to create the above in a dos Makefile send in the changes.

the following commands should then work fine on the command
line.

cd src
make -f ..\Makefile.lcc

===== cross-compiling from Linux =====

Grab ming32:

Wayne Roberts contributed the version used by the maintainer.
(Wayne is largely responsible for bringing rxtx back to win32.)
http://www.linuxgrrls.org/~taj/crossmingw32-2.95-1.i386.rpm
A more current version can be obtained:
http://www.devolution.com/~slouken/SDL/Xmingw32/crossgcc/index.html
prebuilt Binaries:
http://www.devolution.com/~slouken/SDL/Xmingw32/mingw32-linux-x86-glibc-2.1.tar.gz

I built the dll with jdk-1.2.2 for linux using jdk-1.2.2
include files from the win32 JDK.

Make sure that ming32 bin dir is the first in your path (at
least before /usr/bin/gcc)

$ export PATH=" \
/usr/local/cross-tools/i386-mingw32/bin/: \
$PATH:/usr/X11R6/bin:/usr/local/java/bin: \
/usr/local/java/jre/bin/:"

Place Sun jdk 1.2.2 win32 include files in a known location.

$ mkdir /home/jarvi/win32java
$ cp -r /mnt/win98//java/include /home/jarvi/win32java

If you are developing win32 support you may want to
export the location to make the config script
non interactive

$ export WIN32INCLUDE=/home/jarvi/tools/win32-include

run configure to generate a Makefile

$ cd /home/jarvi/rxtx-*
$ mkdir build
$ cd build
$ ../configure --target=i386-mingw32 \
--host=i386-redhat-linux

build the class files and dll.

$ make

the files will be located in

rxtx-*/build/...

If you're looking at rxtx as an example of cross-compiling you
may be interested in looking at the examples provided at:

ftp.xraylith.wisc.edu
/pub/khan/gnu-win32/mingw32/misc/java-jni-examples.zip

=== COMMON PROBLEMS ===

==== I get java.lang.UnsatisfiedLinkError: nSetOwner while loading driver gnu.io.RXTXCommDriver when using rxtx. ====

SetOwner appears to be some win32 call.
Do not use Sun's win32 CommAPI files. Get the Solaris version.
"javacomm20-x86.tar.Z" and rxtx-1.4 if you want Sun's solution.

See Also: 2-B. Installing Sun's comm.jar (IE its not needed at all)

==== Exception in thread "main" java.lang.UnsatisfiedLinkError: no rxtxSerial in java.library.path ====

librxtxSerial.so is located in the wrong directory. Here is an example
<pre>
$ mv /usr/local/java/jre/lib/i386/librxtxSerial* /usr/local/lib
$ java BlackBox
Exception in thread "main" java.lang.UnsatisfiedLinkError: no rxtxSerial
in java.library.path
at java.lang.ClassLoader.loadLibrary(Compiled Code)
at java.lang.Runtime.loadLibrary0(Compiled Code)
at java.lang.System.loadLibrary(Compiled Code)
at gnu.io.NativePort.<clinit>(NativePort.java:32)
at gnu.io.RXTXPort.<init>(Compiled Code)
at gnu.io.RXTXCommDriver.getCommPort(Compiled Code)
at gnu.io.CommPortIdentifier.open(Compiled Code)
at SerialPortDisplay.openBBPort(Compiled Code)
at SerialPortDisplay.<init>(Compiled Code)
at BlackBox.addPort(Compiled Code)
at BlackBox.main(Compiled Code)

... lets fix it.
</pre>
Solution 1: move the file to a place that works

$ mv /usr/local/lib/librxtxSerial.* /usr/local/java/jre/lib/i386/

Solution 2: add the location of librxtxSerial to LD_LIBRARY_PATH

$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib/

Solution 3: pass the location in on the command line

$ java -Djava.library.path=/usr/local/lib/ ...

==== I Can Not Open the Port. ====

If you're not able to open the port (read the errors carefully) then you
may not have permission to use the device.

In particular, Red Hat Linux ships with the following permissions on the /dev/ttyS* device files:

crw-rw---- 1 root uucp /dev/ttyS*

Which means that generally, users do not have read or write access to the serial device.

You could increase the device files' access permissions. Log in as root, then run:

chmod o+rw /dev/ttyS*

Now everyone can read and write the serial devices:

crw-rw-rw- 1 root uucp /dev/ttyS*

However, this is probably not the ideal situation. At the next reboot, the
permissions may have been reset. You may want to have only some users access the device.

Another way of proceeding is to add the user that wants to access /dev/ttyS* to the
"uucp" group as (as can be seen above) group "uucp" has read/write access to the file.

This is done with the command "usermod" or by directly editing "/etc/group" with "vigr".

usermod -G uucp <user-that-wants-access>

Be sure to check the file "CommAPI" for common mistakes.

Also make sure that the user can create lock files.
See [[Installation#How_can_I_use_Lock_Files_with_rxtx.3F|Lockfiles]].
Take note, particularly if you are trying to get 2.1-7r2(final) working on Mac Os X!

==== java.lang.NoClassDefFoundError: gnu/io/CommPort ====

RXTXcomm.jar is probably not in your classpath or not located in
the proper directory.

for example, lets not include RXTXcomm.jar

export CLASSPATH=../java/lib/classes.zip
$ java BlackBoxException in thread "main"
java.lang.NoClassDefFoundError: gnu/io/CommPort

==== The Compiler Cannot Find Java Include Files ====

Check to top of the Makefile to make sure we agree on the location of
the include files that came with the jdk. Specifically:

JAVAINCLUDE = -I /usr/local/java/include/
JAVANATINC = -I /usr/local/java/include/genunix
also check the classpath
CLASSPATH = ...

==== Configure says 'unterminated sed command' and stops ====

Unterminated sed command errors usually result from `find` producing
unexpected results. If you are unsure remove all comm.jar and
configure to place in in the correct place.

==== Java Can Not Find libstdc++-libc6.0-1.so.2 ====

jdk-1.2 on redhat systems may note that Java complains about not being
able to find libstdc++-libc6.0-1.so.2. A symbolic link can be used to
get around this feature.

ln -s /usr/lib/libstdc++ /usr/lib/libstdc++-libc6.0-1.so.2
ls -l /usr/lib/libstdc++-libc6.0-1.so.2
/usr/lib/libstdc++-libc6.0-1.so.2 -> libstdc++.so.2.8.0

==== BlackBox Can Not Handle all the ports! ====

BlackBox has a hard coded limit in BlackBox.java that prevents it from
running if you don't specify a port. We are considering alternative
ways of handling the large number of port names in Unix. The line in
question

is:

portDisp = new SerialPortDisplay[50];

just change 50 to say 256.

==== Illegal use of nonvirtal function call! ====
<pre>
Exception in thread "main" java.lang.VerifyError: (class:
gnu/io/RXTXPort$SerialOutputStream, method: flush signature: ()V)
Illegal use of nonvirtual function call
at gnu.io.RXTXCommDriver.getCommPort(Compiled Code)
at gnu.io.CommPortIdentifier.open(Compiled Code)
at SerialPortDisplay.openBBPort(Compiled Code)
at SerialPortDisplay.<init>(Compiled Code)
at BlackBox.addPort(Compiled Code)
at BlackBox.main(Compiled Code)
</pre>
"1.1 compilers sometimes generate code that won't verify under 1.2.

If you don't have the sources for the offending class to recompile with
a 1.2 javac, the only solution I know of is to launch the VM with the
-noverify option.

Louis"

In other words start with a fresh build directory, rebuild, and
reinstall to avoid the problem.

==== My libc5 Linux system is generating SIGSEGV ====

Older Linux Systems (libc5) should upgrade to a glibc system with
libpthread-0.7 or newer. We have run into many problems with older
libraries. SIGSEGV was the most common symptom. Reported by Peter
Bennett <bencom at bencom.co.nz>

==== AM_PROG_LIBTOOL not found in library ====

cd. && aclocal
aclocal:configure.in: 23: macro 'AM_PROG_LIBTOOL' not found in library
make:***[aclocal.m4]Error 1

If you're positive things are setup right you may try the autogen.sh
script to try regenerating the scripts with your tools.

==== Problems with RMISecurityManager() ====

Please see the file RMISecurityManager.html

==== Which Wires Should be Connected ====

With the DB25 use 2 (TX), 3 (RX) and 7 (GD) to connect to the device.
With the DB9 use 2 (RX), 3 (TX) and 5 (GD) to connect to the device.

You will need to hook up more than that for hardware flow control.

==== Which Device Should be Used? ====

Linux serial ports should use /dev/ttyS?
specialx, cyclades and isdn4 linux have been reported to work.
as many as 64 ports have worked at one time.
FreeBSD uses cuaa?
netbsd uses tty0?
Irix uses ttyd? ttym? ttyf?
HP-UX uses tty0p? tty1p?
BeOS uses /dev/ports/serial?
Win32 uses COM?

==== It Did Not Work! ====

There are sure to be bugs. The goal is to make the install as painless
as possible. Send back comments if something could be easier.

If you run into a problem building the rxtx package please include the
output generated by the following script.
<pre>
---------------clip-----------------
#!/bin/sh
which java
java -version
uname -a
autoconf --version
automake --version
libtool --version
make --version
---------------clip-----------------
</pre>
Here's what's on my system for comparison. Older make is known to cause
problems.

java 1.4
autoconf-2.53
automake-1.6.3
libtool-1.4.2
gnu make-3.79.1

mail any bugs to taj@www.linux.org.uk.

==== Which jdk should be used? ====

This is dated.

Ideally any jdk would be fine. Here is a list of jdk's tried on
RedHat 6.0/kernel 2.2.17pre13 with various versions of glibc.
<pre>
Sun IBM Blackdown
2.1.2_006 1.3.0 1.1.8v1
green native green native green native
------------------------------------------
glibc-2.1.1-6 | OK | *1 | *2 | *2 | OK | *3 |
-------------------------------------------
glibc-2.1.2-11 | OK | *1 | OK | OK | OK | OK |
-------------------------------------------
glibc-2.1.2-17 | OK | *1 | OK | OK | OK | OK |
-------------------------------------------
glibc-2.1.3-15 | OK | *1 | OK | OK | OK | OK |
-------------------------------------------
</pre>
1) BlackBox (a demo application shipped with CommAPI locks after multiple open()/close()

2) java wont start "Unable to load /usr/local/java/jre/bin/libhpi.so: symbol
sem_wait, version GLIBC_2.1 not defined in file libpthread.so.0 with link time
reference Could not create the Java virtual machine."

3) java wont start "error in loading shared libraries:
/usr/local/java/bin/../lib/i686/native_threads/libjava.so: symbol sem_init,
version GLIBC_2.1 not defined in file libpthread.so.0 with link time reference"

Conclusion? Avoid Sun's native threads unless you can figure out whats going wrong. (this is dated)

==== How does rxtx detect ports? Can I override it? ====

rxtx tries to detect ports on by scanning /dev for files matching any
of a set of known-good prefixes, such as 'ttyS', 'ttym', and so on.
Any ones that exist, are supposed to be good for the current operating
system, and that can be read and written are offered back from
CommPortIdentifier.getPortIdentifiers(), and only these can be used as
ports.

If you wish, you can set the system properties gnu.io.rxtx.SerialPorts
and gnu.io.rxtx.ParallelPorts. If either of these is set, then no
scanning will be carried out and only the specified ports will be
available. You can use this to make one platform look like another,
to restrict Java access to ports, or possibly for other reasons. For
example

java -Dgnu.io.rxtx.SerialPorts=/dev/cua/a:/dev/cua/b com.foo.MyApp

will look kind of like Solaris, if you have created the appropriate
device nodes.

A note on Linux port enumeration. We have set most ports aside. Once the
number of possible devices started getting into the thousands, checking them
all made little sense. Look in RXTXCommDriver.java and search for Linux.

You will see that only /dev/ttyS* is searched but the possible addition ports
that can be used are listed under it. Just copy the few you need.

A brief note on '''How to add new enumeration to existing list of ports in Linux?'''

The RXTXcomm.jar file contains all the required classes that work with javax.comm API.
One of them is RXTXCommDriver.class. RXTXCommDriver.java is available in ftp://ftp.qbang.org/pub/rxtx/rxtx-2.0-7pre2/src/
Download the RXTXCommDriver.java. In this code, you will find

if (osName.equals ("Linux"))
{
String[]Temp =
{
"ttyS", // linux Serial Ports
"ttySA" // for the IPAQs
};
CandidatePortPrefixes = Temp;

Replace this code with

if (osName.equals ("Linux"))
{
String[]Temp =
{
"ttyS", "ttyUSB", // linux Serial Ports
"ttySA" // for the IPAQs
};
CandidatePortPrefixes = Temp;
}

Compile the RXTXCommDriver.java and add the resulting RXTXCommDriver.class file to RXTXcomm.jar in
/usr/java/jdk1.5.0_07/jre/lib/ext/RXTXcomm.jar

P.S. : RXTXcomm.jar has two sub directories. gnu->io->RXTXCommDriver.class. Make sure the new compiled file goes into the right place. One way is to extract all files from RXTXcomm.jar. Replace the RXTXCommDriver.class with the new file. Create a new RXTXcomm.jar file using the following command

#jar cvf RXTXcomm.jar gnu META-INF

Replace this new updated jar file with the old one. Then USB to Serial Converters should work great.

==== How can I use Lock Files with rxtx? ====

RXTX uses lock files by default. Lock files are used to prevent more than one program accessing a port at a
time. Lock files may require a bit of sysadmin to work properly.

If you do not want to use lockfiles in RXTX, run 'configure' with option '--disable-lockfiles'.
It is however strongly recommended that you do use lock files to prevent RXTX from stomping on
other programs that might use the serial ports concurrently.

(Don't know if the following is still current. Trent?)

RXTX has support for lock files on Linux only. It may work on other
platforms but read the source before blindly trying it.

The lock file code does not support kermit style lock files or lock files in
'/var/spool'. It is sure to fail if you're using subdirectories in '/dev' or do not
have '/dev'.

Before you use lock files you need to do one of two things:

# Be user 'root' or user 'uucp' on your machine whenever you use RXTX .. or ..
# Add the specific user that needs to use RXTX to the group 'uucp' (preferred)

(On Red Hat, use group 'lock' in addition to 'uucp', see further below.)

To add a user to the 'uucp' group edit '/etc/group' as 'root' (using 'vigr' or your
preferred editor) and change the following:

uucp::14:uucp

to something like:

uucp::14:uucp,jarvi

It may be simpler to just run

usermod -G uucp jarvi

which does exactly the same.

In this case 'jarvi' is the login name for the user that needs to use lock files.
Do not change the number (14). Whatever is in your group file is correct. (On
Red Hat, do this also for group 'lock')

User 'jarvi' in this case can now use RXTX with lock files.

===== Red Hat users =====

In Red Hat, lock files are supposed to be handled by group 'lock' instead of group 'uucp'.

Why: from Red Hat 7.2 upwards. the directory into which lock files are written, '/var/lock',
can only be written to by members of group 'lock'. On the other hand, the serial device
files are owned by group 'uucp' and are not world-writeable by default.

Thus any user (which may or may not actually be using [http://www.uucp.org/index.shtml uucp] ... do people still know what
that was?) that accesses the serial device files must belong to group 'lock' (to create lockfiles) and to group 'uucp'
(to access the device files proper). See also [[Installation#I_Can_Not_Open_the_Port.|I cannot open the port.]]

===== Mandrake users =====

'/var/lock' needs to be owned by group 'uucp'.

===== Mac OS X users =====

You may need to create the lock directory with group 'uucp' ownership. There is a script
in 'contrib' called 'fixperm.sh' to help with this on Mac OS X.

In 2.1-7r2(final) there is a mis-match between the lock file directory given in 'fixperm.sh' that in the source file SerialImp.h (/var/spool/uucp and /var/lock respectively). If you want the binaries to work, you need to replace /var/spool/uucp by /var/lock in fixperm.sh, and run that as root.

===== Lock File server =====

As another option it is possible to use a Lock File Server. In this case,
a server runs in group 'uucp' or 'lock' and rxtx then connects to localhost
to lock and unlock the port. The server and install instructions can be
found in 'src/lfd'. RXTX will need to be configured to use the server:

configure --enable-lockfile_server

Any user can then lock the ports if they are not already locked.

===== Arcana =====

Still cant get things to run under a root account?

Vadim Tkachenko writes:

"Maybe you remember - couple of months back I've run into inability to
run the JDK 1.3+ from under root account.

Today, absolutely suddenly, something clicked in my head and the cause
was found: libsafe. To make JDK work, it is enough to disable libsafe
(unset LD_PRELOAD)."

==== How can I tell which version of rxtx is installed? ====

Version information is not documented in Sun's CommAPI so this is probably
unique to RXTX.

As of rxtx-1.5-4 and rxtx-1.4-6 a class has been added to allow developers to
check which version of rxtx is installed. The class is RXTXVersion.

The static method: System.out.println(RXTXVersion.getVersion());

will print the rxtx version as a String in the following format:

"RXTX-MAJOR.MINOR-PATCH".

an example would be:

"RXTX-1.5-4"

A change in the MAJOR version would suggest you're in trouble.

Odd MINOR version are reserved for development. Even MINOR versions are
reserved for 'stable' releases.

PATCH is used to differentiate incremental releases of the MINOR releases.

CommPortIdentifier is expected to support getVersion() in the RXTX-1.5 series.

==== What Type of Latency can I expect with RXTX ====

frantz <fcapiez at club-internet.fr> put RXTX under a scope and found
the following:

RXTX currently has a latency of 150-200ms on a PII at 450mhz.
The latency can be reduced to 70-80ms by reducing the usleep()
value in SerialImp.c:eventLoop() to usleep(5000)).

Much lower latencies should be possible but the maintainer does not
have equipment to test changes.

He is going to look at this further. He needs 20 ms or less latency.

==== I got rxtx working on a new OS but I can't read from the port ====
<pre>
> Now my java program starts up nicely without complaining. However, it does
> never read any data from the serial port. It looks like it can write data,
> because if I start a terminal program after I tried to run my program, I get
> all the return stuff from the modem that my program wrote.
>
> I hacked around abit and found out that it hangs in the select() call which
> simply never returns.
>
On Sun, 28 Jan 2001, Baldur Norddahl wrote:
> HPUX 11:
>
> As I wrote to the mailinglist I had some wierd problems where it apparently
> could write data to the modem, but not read anything back. My terminal
> programs had no problem using the port. A few days after I reported the
> problem to the mailinglist, I had given up for now, but then I noticed that
> it suddenly worked! So it remains a mystery what was wrong as I did not
> change anything at all, neither in my program nor on the host.
>
> Baldur
>
</pre>

I suspect two java applications had the port open. Its easy to do while
developing. Perhaps <ctl> z instead of <ctl> c was entered.

This is the reason for adding lockfile support to rxtx. If another application
has opened the port, a second application will appear to not be able to
read or get only part of the data. ..because the first one is reading. Only
one of the select()s are waken.

Its possible to put lockfile support in for HPUX if it is known where other
applications place their lockfiles. The easiest way to find out where is
to fire up minicom, kermit, ... and see where its lockfile is placed.

Here are the known suspects:

const char *lockdirs[]={ "/etc/locks", "/usr/spool/kermit",
"/usr/spool/locks", "/usr/spool/uucp", "/usr/spool/uucp/",
"/usr/spool/uucp/LCK", "/var/lock", "/var/lock/modem",
"/var/spool/lock", "/var/spool/locks", "/var/spool/uucp",NULL
};

freebsd uses /var/spool/uucp/, linux uses /var/lock those are the only two
I've done so far. Adding the support is trivial once a directory is
decided upon.

Lockfiles are rather simple. when an application opens a port it first checks
if there is a file with the ports name. If there is it grabs the PID from the
file. If that PID is still active the application does not open the port.

If the PID is not active or there is no lockfile, the application creates one
with its own PID in it.

The confusion starts when you have to decide where (see above) to put the
lockfile, what the name format is for the file and how to store the PID.

rxtx follows The File System Hierarchy Standard http://www.pathname.com/fhs/
on linux. I'm not positive what is normal on other OS's.

more reading:

The File System Hierarchy Standard
http://www.pathname.com/fhs/

FSSTND
ftp://tsx-11.mit.edu/pub/linux/docs/linux-standards/fsstnd/

Proposed Changes to the File System Hierarchy Standard
ftp://scicom.alphacdc.com/pub/linux/devlock-0.X.tgz

"UNIX Network Programming", W. Richard Stevens,
Prentice-Hall, 1990, pages 96-101.
more reading:

==== My ThinkPad is Not Working! ====

Scott Burleigh <Scott.Burleigh at jpl.nasa.gov> writes:

For your files, and in case anybody asks in the
future, IBM Thinkpads ship with the external serial port
*disabled* by default. The Thinkpad configuration utility
supplied with the machine (under Windows) says it's enabled,
and the device manager in the System dialog of the Control
panel says it's enabled, but they lie. In order to enable the
port you have to use the old DOS ps2.exe bios configuration
utility which, under Windows 2000, is in
c:\Program Files\Thinkpad\utilities:

ps2 sera enable

Until you do, "setserial -ga /dev/ttyS0" will always tell you
the UART is unknown.

=== APPLETS ===

More info is needed on signing applets. This is an exchange from the rxtx mail-
list.

==== Using Applets ====

prashantg10 at yahoo.com asked:

Hi All !

I am trying to use applet on thin terminal which has
Linux base Kernel.For testing I am using Linux
machine.I have install all the required components.
e.g. JDK, RXTX. Everthing is fine. BlackBox runs ,even
my application runs. When It comes to applet,
everything is halts. It does not even show the listing
of ports. Is it because applet can't run under root
account or what might be the reasons. Can anybody tell
me solution.

Son To <son@openbx.net> replied:

Java applets run withing the sandbox of the security manager.
Applets must be signed to access the com port, but for development
purposes you can put

user_pref("signed.applets.codebase_principal_support", true);

in your prefs.js located in ~/.mozilla/default/XYYrandomDirName

I didn't use Java applet for my application. I used XUL and CSS for
the GUI development and used mozilla Javascript SOAP library to
communicate with apache Axis webservice backend which uses RXTX to
access the com port.

--
Trent Jarvi
taj@www.linux.org.uk
-------------------------------------------------------------------------------
You made it this far.. what is one more line.

Sun, Solaris and Java are registered trademarks of Sun Microsystems, Inc.

reminder:

redhat 7.1 needs:
export LD_ASSUME_KERNEL=2.2.5

=== User stories ===

==== RXTX and the Equinox SST-4P/LP ====

A note for those who shall try to install an Equinox board (in this case "SST-4P/LP") and try to
run it with RXTX under Linux (in this case, Red Hat ES 4)

Get the driver source from the [http://www.equinox.com/support/download-drivers/ www.equinox.com driver page] and
compile it as described therein.

The four serial ports of the Equinox SST-4P are available as the device files:

/dev/ttyQ1a1 ... /dev/ttyQ1a4

These device files are created by the 'ssmkn' (alias 'make device nodes') executable.

In order to make things work, you have to:

Modify the 'eqnx' startup script '/etc/rc.d/init.d/eqnx'
and make it set the permissions of the devices files in the
'start' section, immediately after the call to 'ssmkn':

# create device files
/usr/bin/ssmkn
# fix rights on device files
LIST=`ls /dev/ttyQ*`
for DEV in $LIST; do
chown root.uucp $DEV
chmod 660 $DEV
done

Modify 'src/RXTXCommDriver.java' in the RXTX distribution. Add
the 'ttyQ1a' radical to the list of port radicals that RXTX checks:

if(osName.equals("Linux"))
{
String[] Temp = {
"ttyS", // linux Serial Ports
"ttySA", // for the IPAQs
"ttyUSB", // for USB frobs
"ttyQ1a" // Equinox
};
CandidatePortPrefixes=Temp;
}

Then recompile and reinstall.

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Installation

Sdhip — Mon, 02 Apr 2007 15:39:53 GMT

Sdhip: /* Mac OS X users */

<pre>
/*-------------------------------------------------------------------------
| rxtx is a native interface to serial ports in Java.
| Copyright 1997-2004 by Trent Jarvi taj@www.linux.org.uk
|
| This library is free software; you can redistribute it and/or
| modify it under the terms of the GNU Library General Public
| License as published by the Free Software Foundation; either
| version 2 of the License, or (at your option) any later version.
|
| This library is distributed in the hope that it will be useful,
| but WITHOUT ANY WARRANTY; without even the implied warranty of
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
| Library General Public License for more details.
|
| You should have received a copy of the GNU Library General Public
| License along with this library; if not, write to the Free
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
--------------------------------------------------------------------------*/
</pre>
This is the INSTALL file for RXTX. Thu Jul 7 19:46:26 EDT 2005

If, while following the instructions, you find this file unclear or incorrect
please make a note and email the details to taj@www.linux.org.uk.

A note about rxtx 2.1:

rxtx 2.1 replaces the entire CommAPI. Every effort is made to conform to
CommAPI but out of respect for our friends at Sun the package name of 2.1 has
been moved to gnu.io. A script is offered in contrib/ChangePackage.sh that
will switch source tree's between javax.comm and gnu.io.

See Sun's CommAPI license for more details on why this decision was made.

If you would like to use javax.comm, use rxtx 1.4 with Sun's CommAPI.
</code>

A note on Mac OS X:

Go to the MacOSX file for install instructions.

-------------------------------------------------------------------------------
=== INSTALL INSTRUCTIONS IN OTHER LANGUAGES ===
==== A. Japanese ====

Instructions are available in Japanese at

The instructions are fairly old but should help.

http://www.geocities.co.jp/Technopolis/4789/settei.htm#id1
Thanks to Masayuki "Tencho" Yamashita <tencho@venus.kanazawa-it.ac.jp>
home page http://www.geocities.co.jp/Technopolis/4789/

A copy of these install instructions is provided in
install-japanese.html

We will gladly include instructions in any language provided. Tencho
was the first to contribute instructions in another language.

=== BUILDING COMMAPI SUPPORT ===

The following is concerned with building and installing commapi
support with Sun's CommAPI package. A full stand alone version of
rxtx is in the CVS archive for interested developers.

==== Quick Install ====

The following packages are used to build rxtx:

autoconf-2.59
automake-1.9.5
libtool-1.5.18
gnu make-3.79.1 On some systems like FreeBSD this is
called gmake
jdk 1.3 or newer

With the packages installed, proceed to build and install rxtx.

<pre>
$ tar -xzvf rxtx-2.1.tar.gz
$ cd rxtx-2.1
$ ./configure (follow the instructions)
$ make install (gmake if your system uses that convention)
Read "R. How can I use Lock Files with rxtx?"
</pre>
One catch that has showed up... you cannot have spaces in the path.
for instance: /home/jarvi/test build/rxtx/... will cause problems.
----^
If that does not work or you do not want a script messing with the
system, read on..

==== Uninstalling Sun's comm.jar ====

Sun's comm.jar is not required. It is a valid option on
some platforms. IT WILL CREATE CHAOS if you have it installed
while trying to build rxtx 2.1.

http://java.sun.com/products/javacomm/index.html

==== Installing javax.comm.properties. ====

javax.comm.properties is not currently required by rxtx-2.1

==== Add RXTXcomm.jar to your CLASSPATH. ====

jdk-1.1:

make sure /usr/local/java/lib/RXTXcomm.jar is in your
CLASSPATH. If you want to use apps that require
RXTXcomm.jar.

in bash:

$ export CLASSPATH=${CLASSPATH}:/usr/local/java/lib/RXTXcomm.jar:.

jdk-1.2 and newer:

No changes are needed.

==== Build and Install the jar. ====

configure configure supports build directories.
configure requires javac in its path or
JAVA_HOME set to grab some java system
properties.
make to build RXTXcomm.jar and the libraries
make install to place the jar and libraries in the correct
location

You may select the JDK you wish to build with using $JAVA_HOME
For example:
export JAVA_HOME=/usr/local/java
Otherwise, configure grabs the JDK from your PATH.

==== Where did everything end up? ====

Lets assume the top java directory is /usr/local/java

jdk-1.2 the files go in
<pre>
/usr/local/java/jre/lib/ext/RXTXcomm.jar
/usr/local/java/jre/lib/$(ARCH)/librxtxSerial.so.
/usr/local/java/jre/lib/$(ARCH)/librxtxParallel.so.
/usr/local/java/jre/lib/$(ARCH)/lib/...

jdk-1.1.* the files go in

/usr/local/java/lib/RXTXcomm.jar
/usr/lib/librxtxSerial.so.
/usr/lib/librxtxParallel.so.
/usr/lib/...

The librxtxSerial.so librxtxParallel.so are placed in
/usr/lib so people don't have to change with their
LD_LIBRARY_PATH.
</pre>

==== Compiling for Win32 support ====

Get the Sun CommAPI if you want a plug-in solution. The code
is provided for people that may have demanding needs and coding
ability.

There is only serial port code at this time.

Three ways of compiling win32 libraries are offered:

mingw32 tools in DOS
lcc tools in DOS
cross-compiling from Linux
===== mingw32 tools in DOS =====

Install mingw32 http://www.mingw.org
Install a jdk http://java.sun.com/j2se
Make sure the ming32\bin and jdk\bin directories are in your
path.
In the rxtx top directory to the following:
mkdir build
copy Makefile.mingw32 build\Makefile
cd build
edit the Makefile and make sure the directories are correct.
execute the following:
make
make install

===== lcc tools in DOS =====

Install a jdk http://java.sun.com/j2se
Install lcc http://www.cs.virginia.edu/~lcc-win32/

A make file (Makefile.lcc) for compiling rxtx with lcc
contributed by Valentin Pavlov

You will need a config.h file in the src directory. Other
builds usually generate them automatically. The following
should work.

#define HAVE_FCNTL_H
#define HAVE_SIGNAL_H
#undef HAVE_SYS_FCNTL_H
#undef HAVE_SYS_FILE_H
#undef HAVE_SYS_SIGNAL_H
#undef HAVE_TERMIOS_H
#undef HAVE_SYS_TIME_H

if you know how to create the above in a dos Makefile send in the changes.

the following commands should then work fine on the command
line.

cd src
make -f ..\Makefile.lcc

===== cross-compiling from Linux =====

Grab ming32:

Wayne Roberts contributed the version used by the maintainer.
(Wayne is largely responsible for bringing rxtx back to win32.)
http://www.linuxgrrls.org/~taj/crossmingw32-2.95-1.i386.rpm
A more current version can be obtained:
http://www.devolution.com/~slouken/SDL/Xmingw32/crossgcc/index.html
prebuilt Binaries:
http://www.devolution.com/~slouken/SDL/Xmingw32/mingw32-linux-x86-glibc-2.1.tar.gz

I built the dll with jdk-1.2.2 for linux using jdk-1.2.2
include files from the win32 JDK.

Make sure that ming32 bin dir is the first in your path (at
least before /usr/bin/gcc)

$ export PATH=" \
/usr/local/cross-tools/i386-mingw32/bin/: \
$PATH:/usr/X11R6/bin:/usr/local/java/bin: \
/usr/local/java/jre/bin/:"

Place Sun jdk 1.2.2 win32 include files in a known location.

$ mkdir /home/jarvi/win32java
$ cp -r /mnt/win98//java/include /home/jarvi/win32java

If you are developing win32 support you may want to
export the location to make the config script
non interactive

$ export WIN32INCLUDE=/home/jarvi/tools/win32-include

run configure to generate a Makefile

$ cd /home/jarvi/rxtx-*
$ mkdir build
$ cd build
$ ../configure --target=i386-mingw32 \
--host=i386-redhat-linux

build the class files and dll.

$ make

the files will be located in

rxtx-*/build/...

If you're looking at rxtx as an example of cross-compiling you
may be interested in looking at the examples provided at:

ftp.xraylith.wisc.edu
/pub/khan/gnu-win32/mingw32/misc/java-jni-examples.zip

=== COMMON PROBLEMS ===

==== I get java.lang.UnsatisfiedLinkError: nSetOwner while loading driver gnu.io.RXTXCommDriver when using rxtx. ====

SetOwner appears to be some win32 call.
Do not use Sun's win32 CommAPI files. Get the Solaris version.
"javacomm20-x86.tar.Z" and rxtx-1.4 if you want Sun's solution.

See Also: 2-B. Installing Sun's comm.jar (IE its not needed at all)

==== Exception in thread "main" java.lang.UnsatisfiedLinkError: no rxtxSerial in java.library.path ====

librxtxSerial.so is located in the wrong directory. Here is an example
<pre>
$ mv /usr/local/java/jre/lib/i386/librxtxSerial* /usr/local/lib
$ java BlackBox
Exception in thread "main" java.lang.UnsatisfiedLinkError: no rxtxSerial
in java.library.path
at java.lang.ClassLoader.loadLibrary(Compiled Code)
at java.lang.Runtime.loadLibrary0(Compiled Code)
at java.lang.System.loadLibrary(Compiled Code)
at gnu.io.NativePort.<clinit>(NativePort.java:32)
at gnu.io.RXTXPort.<init>(Compiled Code)
at gnu.io.RXTXCommDriver.getCommPort(Compiled Code)
at gnu.io.CommPortIdentifier.open(Compiled Code)
at SerialPortDisplay.openBBPort(Compiled Code)
at SerialPortDisplay.<init>(Compiled Code)
at BlackBox.addPort(Compiled Code)
at BlackBox.main(Compiled Code)

... lets fix it.
</pre>
Solution 1: move the file to a place that works

$ mv /usr/local/lib/librxtxSerial.* /usr/local/java/jre/lib/i386/

Solution 2: add the location of librxtxSerial to LD_LIBRARY_PATH

$ export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib/

Solution 3: pass the location in on the command line

$ java -Djava.library.path=/usr/local/lib/ ...

==== I Can Not Open the Port. ====

If you're not able to open the port (read the errors carefully) then you
may not have permission to use the device.

In particular, Red Hat Linux ships with the following permissions on the /dev/ttyS* device files:

crw-rw---- 1 root uucp /dev/ttyS*

Which means that generally, users do not have read or write access to the serial device.

You could increase the device files' access permissions. Log in as root, then run:

chmod o+rw /dev/ttyS*

Now everyone can read and write the serial devices:

crw-rw-rw- 1 root uucp /dev/ttyS*

However, this is probably not the ideal situation. At the next reboot, the
permissions may have been reset. You may want to have only some users access the device.

Another way of proceeding is to add the user that wants to access /dev/ttyS* to the
"uucp" group as (as can be seen above) group "uucp" has read/write access to the file.

This is done with the command "usermod" or by directly editing "/etc/group" with "vigr".

usermod -G uucp <user-that-wants-access>

Be sure to check the file "CommAPI" for common mistakes.

Also make sure that the user can create lock files. See [[Installation#How_can_I_use_Lock_Files_with_rxtx.3F|Lockfiles]].

==== java.lang.NoClassDefFoundError: gnu/io/CommPort ====

RXTXcomm.jar is probably not in your classpath or not located in
the proper directory.

for example, lets not include RXTXcomm.jar

export CLASSPATH=../java/lib/classes.zip
$ java BlackBoxException in thread "main"
java.lang.NoClassDefFoundError: gnu/io/CommPort

==== The Compiler Cannot Find Java Include Files ====

Check to top of the Makefile to make sure we agree on the location of
the include files that came with the jdk. Specifically:

JAVAINCLUDE = -I /usr/local/java/include/
JAVANATINC = -I /usr/local/java/include/genunix
also check the classpath
CLASSPATH = ...

==== Configure says 'unterminated sed command' and stops ====

Unterminated sed command errors usually result from `find` producing
unexpected results. If you are unsure remove all comm.jar and
configure to place in in the correct place.

==== Java Can Not Find libstdc++-libc6.0-1.so.2 ====

jdk-1.2 on redhat systems may note that Java complains about not being
able to find libstdc++-libc6.0-1.so.2. A symbolic link can be used to
get around this feature.

ln -s /usr/lib/libstdc++ /usr/lib/libstdc++-libc6.0-1.so.2
ls -l /usr/lib/libstdc++-libc6.0-1.so.2
/usr/lib/libstdc++-libc6.0-1.so.2 -> libstdc++.so.2.8.0

==== BlackBox Can Not Handle all the ports! ====

BlackBox has a hard coded limit in BlackBox.java that prevents it from
running if you don't specify a port. We are considering alternative
ways of handling the large number of port names in Unix. The line in
question

is:

portDisp = new SerialPortDisplay[50];

just change 50 to say 256.

==== Illegal use of nonvirtal function call! ====
<pre>
Exception in thread "main" java.lang.VerifyError: (class:
gnu/io/RXTXPort$SerialOutputStream, method: flush signature: ()V)
Illegal use of nonvirtual function call
at gnu.io.RXTXCommDriver.getCommPort(Compiled Code)
at gnu.io.CommPortIdentifier.open(Compiled Code)
at SerialPortDisplay.openBBPort(Compiled Code)
at SerialPortDisplay.<init>(Compiled Code)
at BlackBox.addPort(Compiled Code)
at BlackBox.main(Compiled Code)
</pre>
"1.1 compilers sometimes generate code that won't verify under 1.2.

If you don't have the sources for the offending class to recompile with
a 1.2 javac, the only solution I know of is to launch the VM with the
-noverify option.

Louis"

In other words start with a fresh build directory, rebuild, and
reinstall to avoid the problem.

==== My libc5 Linux system is generating SIGSEGV ====

Older Linux Systems (libc5) should upgrade to a glibc system with
libpthread-0.7 or newer. We have run into many problems with older
libraries. SIGSEGV was the most common symptom. Reported by Peter
Bennett <bencom at bencom.co.nz>

==== AM_PROG_LIBTOOL not found in library ====

cd. && aclocal
aclocal:configure.in: 23: macro 'AM_PROG_LIBTOOL' not found in library
make:***[aclocal.m4]Error 1

If you're positive things are setup right you may try the autogen.sh
script to try regenerating the scripts with your tools.

==== Problems with RMISecurityManager() ====

Please see the file RMISecurityManager.html

==== Which Wires Should be Connected ====

With the DB25 use 2 (TX), 3 (RX) and 7 (GD) to connect to the device.
With the DB9 use 2 (RX), 3 (TX) and 5 (GD) to connect to the device.

You will need to hook up more than that for hardware flow control.

==== Which Device Should be Used? ====

Linux serial ports should use /dev/ttyS?
specialx, cyclades and isdn4 linux have been reported to work.
as many as 64 ports have worked at one time.
FreeBSD uses cuaa?
netbsd uses tty0?
Irix uses ttyd? ttym? ttyf?
HP-UX uses tty0p? tty1p?
BeOS uses /dev/ports/serial?
Win32 uses COM?

==== It Did Not Work! ====

There are sure to be bugs. The goal is to make the install as painless
as possible. Send back comments if something could be easier.

If you run into a problem building the rxtx package please include the
output generated by the following script.
<pre>
---------------clip-----------------
#!/bin/sh
which java
java -version
uname -a
autoconf --version
automake --version
libtool --version
make --version
---------------clip-----------------
</pre>
Here's what's on my system for comparison. Older make is known to cause
problems.

java 1.4
autoconf-2.53
automake-1.6.3
libtool-1.4.2
gnu make-3.79.1

mail any bugs to taj@www.linux.org.uk.

==== Which jdk should be used? ====

This is dated.

Ideally any jdk would be fine. Here is a list of jdk's tried on
RedHat 6.0/kernel 2.2.17pre13 with various versions of glibc.
<pre>
Sun IBM Blackdown
2.1.2_006 1.3.0 1.1.8v1
green native green native green native
------------------------------------------
glibc-2.1.1-6 | OK | *1 | *2 | *2 | OK | *3 |
-------------------------------------------
glibc-2.1.2-11 | OK | *1 | OK | OK | OK | OK |
-------------------------------------------
glibc-2.1.2-17 | OK | *1 | OK | OK | OK | OK |
-------------------------------------------
glibc-2.1.3-15 | OK | *1 | OK | OK | OK | OK |
-------------------------------------------
</pre>
1) BlackBox (a demo application shipped with CommAPI locks after multiple open()/close()

2) java wont start "Unable to load /usr/local/java/jre/bin/libhpi.so: symbol
sem_wait, version GLIBC_2.1 not defined in file libpthread.so.0 with link time
reference Could not create the Java virtual machine."

3) java wont start "error in loading shared libraries:
/usr/local/java/bin/../lib/i686/native_threads/libjava.so: symbol sem_init,
version GLIBC_2.1 not defined in file libpthread.so.0 with link time reference"

Conclusion? Avoid Sun's native threads unless you can figure out whats going wrong. (this is dated)

==== How does rxtx detect ports? Can I override it? ====

rxtx tries to detect ports on by scanning /dev for files matching any
of a set of known-good prefixes, such as 'ttyS', 'ttym', and so on.
Any ones that exist, are supposed to be good for the current operating
system, and that can be read and written are offered back from
CommPortIdentifier.getPortIdentifiers(), and only these can be used as
ports.

If you wish, you can set the system properties gnu.io.rxtx.SerialPorts
and gnu.io.rxtx.ParallelPorts. If either of these is set, then no
scanning will be carried out and only the specified ports will be
available. You can use this to make one platform look like another,
to restrict Java access to ports, or possibly for other reasons. For
example

java -Dgnu.io.rxtx.SerialPorts=/dev/cua/a:/dev/cua/b com.foo.MyApp

will look kind of like Solaris, if you have created the appropriate
device nodes.

A note on Linux port enumeration. We have set most ports aside. Once the
number of possible devices started getting into the thousands, checking them
all made little sense. Look in RXTXCommDriver.java and search for Linux.

You will see that only /dev/ttyS* is searched but the possible addition ports
that can be used are listed under it. Just copy the few you need.

A brief note on '''How to add new enumeration to existing list of ports in Linux?'''

The RXTXcomm.jar file contains all the required classes that work with javax.comm API.
One of them is RXTXCommDriver.class. RXTXCommDriver.java is available in ftp://ftp.qbang.org/pub/rxtx/rxtx-2.0-7pre2/src/
Download the RXTXCommDriver.java. In this code, you will find

if (osName.equals ("Linux"))
{
String[]Temp =
{
"ttyS", // linux Serial Ports
"ttySA" // for the IPAQs
};
CandidatePortPrefixes = Temp;

Replace this code with

if (osName.equals ("Linux"))
{
String[]Temp =
{
"ttyS", "ttyUSB", // linux Serial Ports
"ttySA" // for the IPAQs
};
CandidatePortPrefixes = Temp;
}

Compile the RXTXCommDriver.java and add the resulting RXTXCommDriver.class file to RXTXcomm.jar in
/usr/java/jdk1.5.0_07/jre/lib/ext/RXTXcomm.jar

P.S. : RXTXcomm.jar has two sub directories. gnu->io->RXTXCommDriver.class. Make sure the new compiled file goes into the right place. One way is to extract all files from RXTXcomm.jar. Replace the RXTXCommDriver.class with the new file. Create a new RXTXcomm.jar file using the following command

#jar cvf RXTXcomm.jar gnu META-INF

Replace this new updated jar file with the old one. Then USB to Serial Converters should work great.

==== How can I use Lock Files with rxtx? ====

RXTX uses lock files by default. Lock files are used to prevent more than one program accessing a port at a
time. Lock files may require a bit of sysadmin to work properly.

If you do not want to use lockfiles in RXTX, run 'configure' with option '--disable-lockfiles'.
It is however strongly recommended that you do use lock files to prevent RXTX from stomping on
other programs that might use the serial ports concurrently.

(Don't know if the following is still current. Trent?)

RXTX has support for lock files on Linux only. It may work on other
platforms but read the source before blindly trying it.

The lock file code does not support kermit style lock files or lock files in
'/var/spool'. It is sure to fail if you're using subdirectories in '/dev' or do not
have '/dev'.

Before you use lock files you need to do one of two things:

# Be user 'root' or user 'uucp' on your machine whenever you use RXTX .. or ..
# Add the specific user that needs to use RXTX to the group 'uucp' (preferred)

(On Red Hat, use group 'lock' in addition to 'uucp', see further below.)

To add a user to the 'uucp' group edit '/etc/group' as 'root' (using 'vigr' or your
preferred editor) and change the following:

uucp::14:uucp

to something like:

uucp::14:uucp,jarvi

It may be simpler to just run

usermod -G uucp jarvi

which does exactly the same.

In this case 'jarvi' is the login name for the user that needs to use lock files.
Do not change the number (14). Whatever is in your group file is correct. (On
Red Hat, do this also for group 'lock')

User 'jarvi' in this case can now use RXTX with lock files.

===== Red Hat users =====

In Red Hat, lock files are supposed to be handled by group 'lock' instead of group 'uucp'.

Why: from Red Hat 7.2 upwards. the directory into which lock files are written, '/var/lock',
can only be written to by members of group 'lock'. On the other hand, the serial device
files are owned by group 'uucp' and are not world-writeable by default.

Thus any user (which may or may not actually be using [http://www.uucp.org/index.shtml uucp] ... do people still know what
that was?) that accesses the serial device files must belong to group 'lock' (to create lockfiles) and to group 'uucp'
(to access the device files proper). See also [[Installation#I_Can_Not_Open_the_Port.|I cannot open the port.]]

===== Mandrake users =====

'/var/lock' needs to be owned by group 'uucp'.

===== Mac OS X users =====

You may need to create the lock directory with group 'uucp' ownership. There is a script
in 'contrib' called 'fixperm.sh' to help with this on Mac OS X.

In 2.1-7r2(final) there is a mis-match between the lock file directory given in 'fixperm.sh' that in the source file SerialImp.h (/var/spool/uucp and /var/lock respectively). If you want the binaries to work, you need to replace /var/spool/uucp by /var/lock in fixperm.sh, and run that as root.

===== Lock File server =====

As another option it is possible to use a Lock File Server. In this case,
a server runs in group 'uucp' or 'lock' and rxtx then connects to localhost
to lock and unlock the port. The server and install instructions can be
found in 'src/lfd'. RXTX will need to be configured to use the server:

configure --enable-lockfile_server

Any user can then lock the ports if they are not already locked.

===== Arcana =====

Still cant get things to run under a root account?

Vadim Tkachenko writes:

"Maybe you remember - couple of months back I've run into inability to
run the JDK 1.3+ from under root account.

Today, absolutely suddenly, something clicked in my head and the cause
was found: libsafe. To make JDK work, it is enough to disable libsafe
(unset LD_PRELOAD)."

==== How can I tell which version of rxtx is installed? ====

Version information is not documented in Sun's CommAPI so this is probably
unique to RXTX.

As of rxtx-1.5-4 and rxtx-1.4-6 a class has been added to allow developers to
check which version of rxtx is installed. The class is RXTXVersion.

The static method: System.out.println(RXTXVersion.getVersion());

will print the rxtx version as a String in the following format:

"RXTX-MAJOR.MINOR-PATCH".

an example would be:

"RXTX-1.5-4"

A change in the MAJOR version would suggest you're in trouble.

Odd MINOR version are reserved for development. Even MINOR versions are
reserved for 'stable' releases.

PATCH is used to differentiate incremental releases of the MINOR releases.

CommPortIdentifier is expected to support getVersion() in the RXTX-1.5 series.

==== What Type of Latency can I expect with RXTX ====

frantz <fcapiez at club-internet.fr> put RXTX under a scope and found
the following:

RXTX currently has a latency of 150-200ms on a PII at 450mhz.
The latency can be reduced to 70-80ms by reducing the usleep()
value in SerialImp.c:eventLoop() to usleep(5000)).

Much lower latencies should be possible but the maintainer does not
have equipment to test changes.

He is going to look at this further. He needs 20 ms or less latency.

==== I got rxtx working on a new OS but I can't read from the port ====
<pre>
> Now my java program starts up nicely without complaining. However, it does
> never read any data from the serial port. It looks like it can write data,
> because if I start a terminal program after I tried to run my program, I get
> all the return stuff from the modem that my program wrote.
>
> I hacked around abit and found out that it hangs in the select() call which
> simply never returns.
>
On Sun, 28 Jan 2001, Baldur Norddahl wrote:
> HPUX 11:
>
> As I wrote to the mailinglist I had some wierd problems where it apparently
> could write data to the modem, but not read anything back. My terminal
> programs had no problem using the port. A few days after I reported the
> problem to the mailinglist, I had given up for now, but then I noticed that
> it suddenly worked! So it remains a mystery what was wrong as I did not
> change anything at all, neither in my program nor on the host.
>
> Baldur
>
</pre>

I suspect two java applications had the port open. Its easy to do while
developing. Perhaps <ctl> z instead of <ctl> c was entered.

This is the reason for adding lockfile support to rxtx. If another application
has opened the port, a second application will appear to not be able to
read or get only part of the data. ..because the first one is reading. Only
one of the select()s are waken.

Its possible to put lockfile support in for HPUX if it is known where other
applications place their lockfiles. The easiest way to find out where is
to fire up minicom, kermit, ... and see where its lockfile is placed.

Here are the known suspects:

const char *lockdirs[]={ "/etc/locks", "/usr/spool/kermit",
"/usr/spool/locks", "/usr/spool/uucp", "/usr/spool/uucp/",
"/usr/spool/uucp/LCK", "/var/lock", "/var/lock/modem",
"/var/spool/lock", "/var/spool/locks", "/var/spool/uucp",NULL
};

freebsd uses /var/spool/uucp/, linux uses /var/lock those are the only two
I've done so far. Adding the support is trivial once a directory is
decided upon.

Lockfiles are rather simple. when an application opens a port it first checks
if there is a file with the ports name. If there is it grabs the PID from the
file. If that PID is still active the application does not open the port.

If the PID is not active or there is no lockfile, the application creates one
with its own PID in it.

The confusion starts when you have to decide where (see above) to put the
lockfile, what the name format is for the file and how to store the PID.

rxtx follows The File System Hierarchy Standard http://www.pathname.com/fhs/
on linux. I'm not positive what is normal on other OS's.

more reading:

The File System Hierarchy Standard
http://www.pathname.com/fhs/

FSSTND
ftp://tsx-11.mit.edu/pub/linux/docs/linux-standards/fsstnd/

Proposed Changes to the File System Hierarchy Standard
ftp://scicom.alphacdc.com/pub/linux/devlock-0.X.tgz

"UNIX Network Programming", W. Richard Stevens,
Prentice-Hall, 1990, pages 96-101.
more reading:

==== My ThinkPad is Not Working! ====

Scott Burleigh <Scott.Burleigh at jpl.nasa.gov> writes:

For your files, and in case anybody asks in the
future, IBM Thinkpads ship with the external serial port
*disabled* by default. The Thinkpad configuration utility
supplied with the machine (under Windows) says it's enabled,
and the device manager in the System dialog of the Control
panel says it's enabled, but they lie. In order to enable the
port you have to use the old DOS ps2.exe bios configuration
utility which, under Windows 2000, is in
c:\Program Files\Thinkpad\utilities:

ps2 sera enable

Until you do, "setserial -ga /dev/ttyS0" will always tell you
the UART is unknown.

=== APPLETS ===

More info is needed on signing applets. This is an exchange from the rxtx mail-
list.

==== Using Applets ====

prashantg10 at yahoo.com asked:

Hi All !

I am trying to use applet on thin terminal which has
Linux base Kernel.For testing I am using Linux
machine.I have install all the required components.
e.g. JDK, RXTX. Everthing is fine. BlackBox runs ,even
my application runs. When It comes to applet,
everything is halts. It does not even show the listing
of ports. Is it because applet can't run under root
account or what might be the reasons. Can anybody tell
me solution.

Son To <son@openbx.net> replied:

Java applets run withing the sandbox of the security manager.
Applets must be signed to access the com port, but for development
purposes you can put

user_pref("signed.applets.codebase_principal_support", true);

in your prefs.js located in ~/.mozilla/default/XYYrandomDirName

I didn't use Java applet for my application. I used XUL and CSS for
the GUI development and used mozilla Javascript SOAP library to
communicate with apache Axis webservice backend which uses RXTX to
access the com port.

--
Trent Jarvi
taj@www.linux.org.uk
-------------------------------------------------------------------------------
You made it this far.. what is one more line.

Sun, Solaris and Java are registered trademarks of Sun Microsystems, Inc.

reminder:

redhat 7.1 needs:
export LD_ASSUME_KERNEL=2.2.5

=== User stories ===

==== RXTX and the Equinox SST-4P/LP ====

A note for those who shall try to install an Equinox board (in this case "SST-4P/LP") and try to
run it with RXTX under Linux (in this case, Red Hat ES 4)

Get the driver source from the [http://www.equinox.com/support/download-drivers/ www.equinox.com driver page] and
compile it as described therein.

The four serial ports of the Equinox SST-4P are available as the device files:

/dev/ttyQ1a1 ... /dev/ttyQ1a4

These device files are created by the 'ssmkn' (alias 'make device nodes') executable.

In order to make things work, you have to:

Modify the 'eqnx' startup script '/etc/rc.d/init.d/eqnx'
and make it set the permissions of the devices files in the
'start' section, immediately after the call to 'ssmkn':

# create device files
/usr/bin/ssmkn
# fix rights on device files
LIST=`ls /dev/ttyQ*`
for DEV in $LIST; do
chown root.uucp $DEV
chmod 660 $DEV
done

Modify 'src/RXTXCommDriver.java' in the RXTX distribution. Add
the 'ttyQ1a' radical to the list of port radicals that RXTX checks:

if(osName.equals("Linux"))
{
String[] Temp = {
"ttyS", // linux Serial Ports
"ttySA", // for the IPAQs
"ttyUSB", // for USB frobs
"ttyQ1a" // Equinox
};
CandidatePortPrefixes=Temp;
}

Then recompile and reinstall.

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