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Showing content with the highest reputation on 04/22/2012 in all areas

  1. Just read 65k bytes (or 1500 bytes is better for the reasons Rolf outlined) from the file at a time and write it using the UDP write. However. As GregR stated. It is not guaranteed to be recieved in the correct order, or indeed a chunk to be received at all! So that's not a lot of good for files, but usually acceptable for audio or video where a lost frame or two doesn't matter too much. The easy solution, as others are saying, is to use TCPIP where all the ordering and receiving reassembly is handled for you (as well as other things UDP doesn't do out-of-the-box such as congestion control, re-transmission of lost packets etc). If you really must use UDP then you will have to code all that yourself (unless missing or incorrectly ordered file chunks is acceptable-for TDMS it wouldn't be). There are a few examples of reliable UDP (RDP). Noteably UDT and NORM. I am not aware of anyone doing this in Labview however, since it is just easier to use TCPIP.
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  2. And going beyond 1500 bytes MTU is only an option if you are on a controlled network where you do know about all routers involved between the two parties. Once you go outside of that, such as an internet connection, the maximum MTU is entirely out of your hands and going beyond the default of 1500 bytes is really playing chances that the communication will actually work, unless you do a lot extra work in reassembling the incoming packages into the right order on the receiving end. And that is something that is even on embedded devices usually handled much more efficiently by the TCP protocol level, so why go to the hassle of UDP in that case? As to data transfer of LabVIEW TCP, it has some overhead in its internal buffer handling but I have in the past reached half the bandwidth of the network without to much trouble, as long as you don't do a two way handshake for every packet send. There used to be some challenges in older LabVIEW versions, with LabVIEW simply loosing data or even crashing on heavy network load (supposedly some rare race conditions in its socket handling), but I haven't seen such things in newer LabVIEW versions.
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  3. No. I'm saying the payload cannot exceed 65k. If you can send 1 payload (of 65k) every 10ms then that would be 6.5 MB/sec
    1 point
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