并行口通信Rxtx或javax.comm

Question

目前，我正试图通过Java与并行端口通信，但事实证明这很麻烦。我目前正在做一项脑研究，使用EEG，我想发送简单的“事件标记”到EEG系统，这必须通过并行口。我同时使用了javax.comm和RXTX，但由于某种原因，我无法将输出写入端口。测试代码如下：

import gnu.io.*; // RXTX
// import javax.comm.*; // javax.comm

public class PrlCom {
private String msg= "1";

private OutputStream outputStream;
private InputStream inputStream;

private ParallelPort parallelPort; // can be both Rxtx or javax.comm 
private CommPortIdentifier port;

// CONSTANTS
public final String PARALLEL_PORT = "LPT1";
public final String[] PORT_TYPE = { "Serial Port", "Parallel Port" };

public static void main(String[] args) {
    new PrlCom();
}
public PrlCom(){
    openParPort();
}

public void openParPort() {
    try {
        // get the parallel port connected to the EEG-system (used to be printer)
        port = CommPortIdentifier.getPortIdentifier(PARALLEL_PORT);

        System.out.println("\nport.portType = " + port.getPortType());
        System.out.println("port type = " + PORT_TYPE[port.getPortType() - 1]);
        System.out.println("port.name = " + port.getName());

        // open the parallel port -- open(App name, timeout)
        parallelPort = (ParallelPort) port.open("CommTest", 50);
        outputStream = parallelPort.getOutputStream();
        inputStream = parallelPort.getInputStream();

        System.out.println("Write...");
        outputStream.write(toBytes(msg.toCharArray()));
        System.out.println("Flush...");
        outputStream.flush();
    } catch (NoSuchPortException nspe) {
        System.out.println("\nPrinter Port LPT1 not found : " + "NoSuchPortException.\nException:\n" + nspe + "\n");
    } catch (PortInUseException piue) {
        System.out.println("\nPrinter Port LPT1 is in use : " + "PortInUseException.\nException:\n" + piue + "\n");
    } catch (IOException ioe) {
        System.out.println("\nPrinter Port LPT1 failed to write : " + "IOException.\nException:\n" + ioe + "\n");
    } catch (Exception e) {
        System.out.println("\nFailed to open Printer Port LPT1 with exeception : " + e + "\n");
    } finally {
        if (port != null && port.isCurrentlyOwned()) {
            parallelPort.close();
        }

        System.out.println("Closed all resources.\n");
     }
}

我从Converting char[] to byte[]获得了Converting char[] to byte[]()函数。我还直接尝试了spam.getBytes()，这并没有什么不同。

在使用javax.comm包运行此代码后，将无法识别并行端口。如果我使用RXTX(gnu.io)运行代码，就会得到一个IOException。然后，整个打印输出如下

Stable Library
=========================================
Native lib Version = RXTX-2.1-7
Java lib Version   = RXTX-2.1-7

port.portType = 2
port type = Parallel Port
port.name = LPT1
Output stream opened
Write...

Printer Port LPT1 failed to write : IOException.
Exception:
java.io.IOException: The device is not connected.
    in writeByte

Closed all resources.

使用Rxtx，代码可以因此与并行口建立连接。但是，它无法将字节写入输出流。谁能告诉我怎么解决这个问题吗？

我在许多其他主题中读到了并行端口是多么的过时，我应该使用USB。然而，我正在使用脑电系统(BioSemi ActiveTwo和ActiView软件)来测量大脑活动，不幸的是，我没有可能改变这一点。并口-USB转换器也是没有选择的.(但奇怪的是，如此先进的技术却使用了如此过时的硬件)。

非常感谢!

Answer 1

我已经接受了Rxtx和javax.comm不再工作了。相反，我通过Python找到了一个解决办法。有关答案，请参见Parallel Port Communication with jnpout32pkg / jnpout32reg