· Thin Client Hardware Requirements (Windows CE 5. not support audio-input. stop in the current buffer transmission. The serial port must also. Serial Port programming in Linux using C - Working code. ("unable to set comport time-out settings \n. // Read the data received in the serial port buffer. Serial Programming/Serial Java - Wikibooks, open books for an open world. Serial Programming: Introduction and OSI Network Model - - RS- 2. Wiring and Connections - - Typical RS2. Hardware Configuration - - 8. UART - - DOS - - MAX2. Driver/Receiver Family - - TAPI Communications In Windows - - Linux and Unix - - Java - - Hayes- compatible Modems and AT Commands - - Universal Serial Bus (USB) - - Forming Data Packets - - Error Correction Methods - - Two Way Communication - - Packet Recovery Methods - - Serial Data Networks - - Practical Application Development - - IP Over Serial Connections. Using Java for Serial Communication[edit]Introduction[edit]Because of Java's platform- independence, serial interfacing is difficult. Serial interfacing requires a standardized API with platform- specific implementations, which is difficult for Java. Unfortunately, Sun didn't pay much attention to serial communication in Java. Sun has defined a serial communication API, called Java. Comm, but an implementation of the API was not part of the Java standard edition. Sun provided a reference implementation for a few, but not all Java platforms. Particularly, at the end of 2. Sun silently withdrew Java. Comm support for Windows. Third party implementations for some of the omitted platforms are available. Java. Comm hasn't seen much in the way of maintenance activities, only the bare minimum maintenance is performed by Sun, except that Sun apparently responded to pressure from buyers of their own Sun Ray thin clients and adapted Java. Comm to this platform while dropping Windows support. This situation, and the fact that Sun originally did not provide a Java. Comm implementation for Linux (starting in 2. Rx. Tx library. Rx. Tx is available for a number of platforms, not only Linux. It can be used in conjunction with Java. Comm (Rx. Tx providing the hardware- specific drivers), or it can be used stand- alone. When used as a Java. Comm driver the bridging between the Java. Comm API and Rx. Tx is done by JCL (Java. Comm for Linux). JCL is part of the Rx. Tx distribution. Sun's negligence of Java. Comm and Java. Comm's particular programming model gained Java. Comm the reputation of being unusable.
Rx. Tx - if not used as a Java. Comm driver - provides a richer interface, but one which is not standardized. Rx. Tx supports more platforms than the existing Java. Comm implementations. Recently, Rx. Tx has been adopted to provide the same interface as Java. Comm, only that the package names don't match Sun's package names. So, which of the libraries should one use in an application? If maximum portability (for some value of "maximum") is desired, then Java. Comm is a good choice. If there is no Java. Comm implementation for a particular platform available, but an Rx. Tx implementation is, then Rx. Tx could be used as a driver on that platform for Java. Comm. So, by using Java. Comm one can support all platforms which are either directly supported by Sun's reference implementation or by Rx. Tx with JCL. This way the application doesn't need to be changed, and can work against just one interface, the standardized Java. Comm interface. This module discusses both Java. Comm and Rx. Tx. It mainly focuses on demonstrating concepts, not ready- to- run code. Those who want to blindly copy code are referred to the sample code that comes with the packages. Those who want to know what they are doing might find some useful information in this module. SSC (Java Simple Serial Connector) should also be considered. There is also another library called j. Serial. Comm that includes all its platform specific files in its jar, this makes it truly portable as there is no installation necessary. Getting started[edit]Learn the basics of serial communication and programming. Have the documentation of the device you want to communicate with (e. Set up all hardware and a test environment. Use, for example, a terminal program to manually communicate with the device. This is to be sure the test environment is set up correctly and you have understood the commands and responses from the device. Download the API implementation you want to use for your particular operating system. Read. the Java. Comm and/or Rx. Tx installation instruction (and follow it)the API documentationthe example source code shipped. Installation[edit]General Issues[edit]Both Java. Comm and Rx. TX show some installation quirks. It is highly recommended to follow the installation instructions word- for- word. If they say that a jar file or a shared library has to go into a particular directory, then this is meant seriously! If the instructions say that a particular file or device needs to have a specific ownership or access rights, this is also meant seriously. Many installation troubles simply come from not following the instructions precisely. It should especially be noted that some versions of Java. Comm come with two installation instructions. One for Java 1. 2 and newer, one for Java 1. Using the wrong one will result in a non- working installation. On the other hand, some versions/builds/packages of Rx. Tx come with incomplete instructions. In such a case the corresponding source code distribution of Rx. Tx needs to be obtained, which should contain complete instructions. Many linux distributions offer a Rx. Tx package in their repositories (Arch. Linux - 'java- rxtx', Debian/Ubuntu - 'librxtx- java'), these packages include only the platform specific parts of the library, but are generally ready to use. It should be further noticed that it is also typical for Windows JDK installations to come with up to three VMs, and thus three extension directories. One as part of the JDK,one as part of the private JRE which comes with the JDK to run JDK tools, andone as part of the public JRE which comes with the JDK to run applications. Some even claim to have a fourth JRE somewhere in the \Windows directory hierarchy. Java. Comm should at least be installed as extension in the JDK and in all public JREs. Webstart[edit]Java. Comm[edit]A general problem, both for Java. Comm and Rx. Tx is, that they resist installation via Java Web. Start: Java. Comm is notorious, because it requires a file called javax. JDK lib directory, something which can't be done with Java Web. Start. This is particularly sad, because the need for that file is the result of some unnecessary design/decision in Java. Comm and could have easily been avoided by the Java. Comm designers. Sun constantly refuses to correct this error, citing the mechanism is essential. Which is, they are lying through their teeth when it comes to Java. Comm, particular, because Java for a long time has a service provider architecture exactly intended for such purposes. The contents of the properties file is typically just one line, the name of the java class with the native driver, e. Win. 32. Driver. The following is a hack which allows to deploy Java. Comm via Web Start ignoring that brain- dead properties file. It has serious drawbacks, and might fail with newer Java. Comm releases - should Sun ever come around and make a new version. First, turn off the security manager. Some doofus programmer at Sun decided that it would be cool to again and again check for the existence of the dreaded javax. System. set. Security. Manager(null); Then, when initializing the Java. Comm API, initialize the driver manually: Stringdriver. Name="com. sun. comm. Win. 32. Driver"; // or get as a JNLP property. Comm. Drivercomm. Driver=(Comm. Driver)Class. Name(driver. Name). Instance(); comm. Driver. initialize(); Rx. Tx on some platforms requires changing ownership and access rights of serial devices. This is also something which can't be done via Web. Start. At startup of your program you could ask the user to perform the necessary setup as super user. Further, Rx. Tx has a pattern matching algorithm for identifying "valid" serial device names. This often breaks things when one wants to use non- standard devices, like USB- to- serial converters. This mechanism can be overridden by system properties.
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