LabVIEW
How is LabView interfaced to a C++ application?
As has been already suggested, I'v written a pipe library for LabVIEW for Windows and made it available at www.openg.org. It's not released and still considered beta but it seems to work for what I needed it.
@dj143 wrote:I'm working with a C++ programmer that has an application that I need to obtain data from and send the data to my LabVIEW application. I assume that this would be a server/client relationship where I would be the client. The C++ programmer feels that we should be able to do this by using what is called "named pipes." I'm not sure how to approach this because I'm not an experienced programmer (which is why I use LabVIEW).In case it's relevant, I also have access to LabWindows/CVI v.8.1.1. I don't know anything about LabWindows, athough I'm willing to learn if I need to. I have the LabWindows product available because it is part of my quarterly NI Developer Suite update.I'd appreciate it if someone would steer me in the right direction by way of a knowledge base or other documentation. I'm currently using the Professional version of LabVIEW, v.8.5 and Win XP.Thanks,Dave
As to using the Call Library Node, that would be only feasable if the C++ application would somehow offer a DLL function interface (standard C functions only) or be turned into a DLL althogether. The Code Interface Node does not provide any advantages to the Call Library Node but has some serious disadvantages nowadays and should not be used for new developments anymore.
As to other inter-application communication the crudest would be file IO, pipe is interesting but also a bit tricky, and TCP/IP is normally my first choice if I can use it. It's a bit more work on the server side usually than using pipes but it is rock solid, very well proven and last but not least has the additional benefit to support remote communication out of the box if that need ever should arise. And for most purposes it is not slower than pipes.
Other more obscure things could be shared memory, or DDE (ouch), with the first also not being a standard LabVIEW supported technique (for some good reason actually) and the second being an old and slow legacy techique.
Rolf Kalbermatter
I have to admit that I'm at the moment not very intimate with the internal workings of the OpenG pipe library. From what I can remember pipes are unidirectional entities so if you want to read and write, you have to open one pipe for each direction (under different names). I guess the shared library could have handled that internally and offer the user the option to also do bidirectional operation, but that is not what I have gone with at the time of development. The named pipe support was in fact a sorts of afterthought as I was concentrating on standard IO redirection for command line tools and there only unidirectional operation was possible.
So there might be a problem to use the OpenG pipe library with your specific use case at this time. I'm rather busy at the moment and don't really have much time to look deeper into this. But if it is for a specific project you have don't hesitate to contact me or our office in Hasselt to talk about possible options.
