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    <p>I have a similar application here and use TCP sockets with the TCP_NO_DELAY option set (disables the Nagle algorythm which does some sort of packet buffering). Sockets should allow for a 100mSec update rate without problems, although the actual network delay will always remain an unknown variable. For my application this does not matter as long as it stays under a certain limit (this is also checked for by sending a timestamp with each packet and big red dialog boxes if timestamp delta becomes too large :]). Does it matter for your application? Ie, is it important that whenever the LV instrument acquires a new sample it's value has to make it to the C app within x mSec?</p> <p>You might get the dll approach working, but it's not as straightforward as sockets and it will make the two applications more dependant of each other. Variable acces will be pretty much instantaneous though. I see at least two possibilities:</p> <ul> <li>put your <em>entire</em> C app in a dll (might seem a weird approach at first but it works), and have LV load it and call methods on it. Eg to start your app LV calls dll's Start() method, then in the loop LV acquires it's samples it calls the dll's NewSampleValue(0 method or so. Also means your app cannot run standalone unless you write a seperate host process for it.</li> <li>look into shared process memory, and have the C app and another dll share common memory. LV will load that dll and call a method on it to write a value to the shared memory, then the C app can read it after polling a flag (which needs a lock!).</li> <li>it might also be possible to have the C app call the LV program using dll/activeX/? calls but I don't know how that system works..</li> </ul> <p>I would definitely stay away from the file approach: disk I/O can be a real bottleneck and it also has the locking problem which is messy to solve with files. C app cannot read the file while LV is writing it and vice-versa which might introduce extra delays.</p> <p>On a sidenote, you can see that each of the approaches above either use a push or pull model (the TCP one can be implemented in both ways), this might affect your final decision of which way to go.. Push = LV signals the C app directly, pull = C app has to poll a flag or ask LV for the value.</p>
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