Reading the same port on the same machine
Hello,
i'm working on DatagramSocket to broadcast DatagramPacket (IP 192.168.xxx.255) and a fixed num port. The problem is that I can't have 2 threads that read (datagramSocket.read) on the same port, on the same machine.
How can I perform my tests ?
java.net.BindException: Address already in use
at java.net.PlainDatagramSocketImpl.bind(Native Method)
at java.net.DatagramSocket.bind(DatagramSocket.java:368)
at java.net.DatagramSocket.<init>(DatagramSocket.java:210)
at java.net.DatagramSocket.<init>(DatagramSocket.java:261)
at java.net.DatagramSocket.<init>(DatagramSocket.java:234)
Well, the short answer is that you can't.... at least I've never heard of a way how. Basically, when an application requests a port number, it basically owns that port number until it gives it up. You do this when you create the DatagramSocket. Each DatagramSocket is its own request, and therefore must have an unique identifying port. Otherwise, how would your operating system know who to give the data to when it receives a packet on your machine for port XXXX? Also, it would be a secuirity problem if other applications could listen on the same port as you use for other things like surfing the web, making online purchases, email.
However, what you could do is have one owner of the DatagramSocket... and share it among the other threads. When that owner receives a packet, it can notify the other threads it received a packet and pass the data to each one. Set it up something like how listeners work. Also, if you want it to span processes, you could use RMI or pass the data through other deined network connections between the processes.
Does that make sense? :)
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Generated Pulse waveform is distorted when I deliver the signal to the output port in the DAQmx
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Environment: Windows XP sp3 (32bit), Visual Studio 2010 sp1, NI-Measurement Studio 2010
Device: NI - DAQmx PCI 6251
Analog Input: 1.00MS/s multi-channel (aggregate)
Analog Output: 2 Channel 2.00MS/s
Reference Example: AO_ContGenVoltageWfm_IntClk / AI_ContAcqVoltageSamples_IntClk
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Program Code
AO_ContGenVoltageWfm_IntClk / AI_ContAcqVoltageSamples_IntClk (VC++ Example)
Result: The proposed approach was implemented in the experiment environment (VS2010, MStudio2010). As shown in Figure 1, we could get the unsatisfied result. Although I intended to make a ‘square’ pulse wave, the result looks like ‘trapezoid’ pulse wave (Figure.1). However, there is other result which was undertaken with different parameter condition. It looks like the square shape not the trapezoid shape.
Please let me know what the conditions make the problem of signal distortion. (AO0 = Green line / AO1 = Red line)
[Figure. 1] Frequency 8000 Hz / Cycle per Buffer = 8000 Result
[Figure. 2] Frequency 1000 Hz / Cycle per Buffer = 1000 Result
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1) Is it possible to deliver the generated pulse wave satisfied with constraints (f= 8KHz), △t = 0.5㎲/sample) to the output port without distortion using PXI 6251?
(Is it possible to solve the problem, if I use the LabView or MAX?)
2) Are there some mistakes in the proposed approach? (H/W or S/W program)
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Thanks for your reply. For your information, I have set the sampling rate as 10000 as for the sound format, I have set the bits per sample as 16 bit, the rate as 11025 and the sound quality as mono. I tried using your method by changing the sampling rate as 8K but still my program encounter the same problem.
I wish to also create a button that is able to generate a preformatted report that contains VI documentation, data the VI returns, and report properties, such as the author, company, and number of pages only when I click on the button. I have created this in my program, but I am not sure why is it not working. Can you help troubleshoot my program. Or do you have any samples to provide me. Hope to hear from you soon.
Many thanks.
Regards,
min
Attachments:
Heart Sounds1.vi 971 KB
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