How to generate non-blocking commands to a serial device
I have a serial device which accepts non-blocking commands. This is, if you send a command that takes 1 minute, while this happens, you can send more commands and they will be executed. Once a command is done, it sends back a code that relates to that command, so you know it is finished.
I have a VI which tries to communicate with this serial device (see attachment). It does work, but it blocks the execution until a command is finished. So I can send commands one by one, but not in parallel, or in a delayed non-block way. The problem is the while loop which waits until the device outputs something.
I need to do something similar, but non blocking. The VI should be able to send several commands while others are executed.
This subVI is controlled from a main VI, which is just a State Machine with a few states, where each state is some action which is sent to this subVI, and then to the serial device.
Attachments:
blocking_vi.png 27 KB
Use another loop that does nothing but read from the serial port. Report the data to whoever needs it with a Queue.
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Set ready = selector.selectedKeys();
Iterator i = ready.iterator();
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try {
SelectionKey sk = i.next();
i.remove();
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Hello Techies,
How to set sockets in the non-blocking mode and what is the main use of setting sockets in non-blocking mode.
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Ramu.Hello Techies,
Thanks for u r replies,
Finally i had understood how to use nio. But the problem is it is going into infinite loop. Here is my code.
package networking;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.util.Iterator;
public class testSocketChannel {
* @param args
public static ByteBuffer buf ;
public static SocketChannel clientChannel;
public static void main(String[] args) {
// TODO Auto-generated method stub
try
Selector selector = Selector.open();
clientChannel = SocketChannel.open();
clientChannel.configureBlocking(false);
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clientChannel.connect(new InetSocketAddress("localhost",90));
clientChannel.register(selector,clientChannel.validOps());
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while (true)
try {
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selector.select();
} catch (IOException e) {
// Handle error with selector
//break;
// Get list of selection keys with pending events
Iterator it = selector.selectedKeys().iterator();
// Process each key at a time
//while (it.hasNext())
for(int i = 0;i<selector.selectedKeys().size();i++)
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try
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Need quick replies.
Ramu
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