So summarize:. However, in the typical Sun manner this mechanism is not without problems. In principle an application can register event listeners with a particular SerialPort to be kept informed about important events happening on that port. The two most interesting event types for reading and writing data are. Before going into details, the next section will present the principal way of implementing and registering a serial event handler. Remember, there can only be one handler at all, and it will have to handle all possible events.
Once the listener is implemented, it can be used to listen to particular serial port events. To do so, an instance of the listener needs to be added to the serial port. Further, the reception of each event type needs to be requested individually. Using a separate thread for writing has one purpose: Avoiding that the whole application blocks in case the serial port is notready for writing.
Using a separate thread for writing, separate from some main application thread, implies that there is some way to hand off the data which needs to be written from the application thread to the writing thread.
A shared, synchronized data buffer, for example a byte[] should do. Further, there needs to be a way for the main application to determine if it can write to the data buffer, or if the data buffer is currently full. In case the data buffer is full it could indicate that the serial port is not ready, and output data has queued up.
The main application will have to poll the availability of new space in the shared data buffer. However, between the polling the main application can do other things, for example updating a GUI, providing a command prompt with the ability to abort the sending, etc.
But Sun wouldn't be Sun if the a piped stream would actually be useful. So the application thread would block. Exactly what one wants to avoid by using the separate thread. A java. Pipe suffers from the same problem. Its blocking behavior is platform dependent.
In this article a very simple synchronized ring buffer is used to hand over the data from one thread to another. In a real world application it is likely that the implementation should be more sophisticated.
A ring buffer as such is nothing special, and has no special properties regarding threading. It is just that this simple data structure is used here to provide data buffering. The implementation is done so that access to this data structure has been made thread safe.
With this ring buffer one can now hand over data from one thread to another in a controlled way. Any other thread-safe, non-blocking mechanism would also do. The key point here is that the write does not block when the buffer is full and also does not block when there is nothing to read. The event is not supported by all JavaComm implementations, therefore the code might never be called.
However, in case the event is available it is one building block for ensuring best data throughput, because the serial interface is not left idle for too long. The skeleton event listener proposed a method outputBufferEmpty , which could be implemented as it follows.
The following example assumes that the data's destination is some file. Whenever data becomes available it is fetched from the serial port and written to the file. This is an extremely simplified view, because in reality one would need to check the data for an end-of-file indication to, for example, return to the modem command mode.
JavaComm is strictly concerned with the handling of a serial interface and the transmission of data over that interface.
It does not know, or provide, any support for higher-layer protocols, e. This is simply not the job of JavaComm, and not a bug. Like with any other particular serial device, if the control of a modem is desired via JavaComm the necessary code has to be written on top of JavaComm. The page 'Hayes-compatible Modems and AT Commands' provides the necessary basic generic information to deal with Hayes modems. Some operating systems, e.
Windows or certain Linux distributions provide a more or less standardized way how modem control commands for a particular modem type or brand are configured for the operating system.
Windows modem 'drivers', for example, are typically just registry entries, describing a particular modem the actual driver is a generic serial modem driver. JavaComm as such has no provisions to access such operating-system specific data. Therefor, one either has to provide a separate Java-only facility to allow a user to configure an application for the usage of a particular modem, or some platform-specific native code needs to be added.
RxTx was then further ported to other platforms. In order to do the latter, a wrapper called JCL is also needed [2]. So, before trying to get them separately, it is worth having a look at the Linux distribution CD. No need to connect it to laptop. Can you use this software to capture print from the instrument to the computer? Add a comment. Active Oldest Votes. I suggest breaking the problem into two phases: Capture the output from the printer to a file via a terminal emulator connected to the virtual serial port.
Ultimately, a serial connection just transmits a stream of bytes. A terminal emulator should be able to connect to the virtual serial port offered by the USB adapter, and give you an option to save the received data to a file.
You will need to do some research to find a terminal emulator that will serve your needs. Use a converter application to convert the printer data to PDF.
Off the top of my head, Ghostscript might do the job but I have not used it in a while. Rob Lyman Rob Lyman 1 1 silver badge 7 7 bronze badges. Sign up or log in Sign up using Google. I have done a bit of googling, and it seems that there isn't a very good way to interface between javascript and rs Install a webserver.
I think you'll need to add a Java or Active-X layer in between. JavaScript is pretty well isolated deliberately from the OS. Javascript in particular, or just from the browser with some method? And which browser? IE or Firefox? Alternatively you could use JSDB as an impromptu web server on an alternate port of the local machine. The SourceForge downloads page has version 2. Another problem that arises with the read methods is that if there is no data in the input buffer when you call them, they will stall the execution of your program until there is valid data to read this is similar behavior to the Console.
A better way to be continuously reading is to check if there is data to be read in the input buffer using the SerialPort. BytesToRead property. This property returns the number of bytes in the input buffer that need to be read. With this we could set up a loop that will skip over the read code if there is nothing in the input buffer.
What if you were creating a large complex program that was handling many tasks and would not be able to work within the confines of an infinite loop?
Luckily for you, the SerialPort class has created an event that is raised whenever there is new data in the input buffer. In our case when data is received by the input buffer, the event will stop the program, call a method where we would most likely handle the data, and then go back to where our program left off. We will delve into this in the next step. The first thing we need to do is to tell our serial port what method to call when it receives data. This is done with the following line: mySerialPort.
DataReceived represents the method that is called to handle the event. Just one more note: you will want to make sure when using events that you declare your SerialPort object as a class level field so that you can use it in multiple methods including the event handler. Different methods and procedures fit different situations, so you will have to find one that works and that you like to use.
I personally like using the events whenever possible since they are the most efficient and leave the program free to do other things, but everyone has their preferences. In the next step I am going to talk about how to write to a serial port. Good news! Writing to a port is incredibly easy! The other two write methods are also similar; the only difference is the data type of the data to send.
To use them, you provide an array of bytes or characters which will be written to the serial port. The offset parameter just specifies what element of the array to start at i. If you pass it 0, it will start at the very beginning of the array; if you pass 1 it will start at the second element.
The length parameter is simply the length of the array.
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