LabVIEW
Configuring dll using call library function node
The Import Library Wizard is a handy feature to do the repetitive work of generating wrapper VIs for DLL functions. However it can not replace a good programmer who knows what he or she is doing.
The Import Library Wizard is an automatic tool that can take the header file and TRY to create the VI to call a particular function. But the C syntax in the header file is notoriously insufficient to describe all aspects of the function interface. It only (and even that often insufficiently) describes the datatypes of the parameters, their order and pretty much nothing else. Consequently the Import Library Wizard can not invent out of the air new knowledge about how to really properly call that function.
Generally said: If you can't create the function calls correctly yourself, the Import Library Wizard will seem to be a solution but it will only give you a false security. It will in most cases create a library that either doesn't work at all due to more or less frequent crashes, or even though it doesn't seem to crash, inevitably will corrupt memory somewhere and cause problems down the road, preferably after you have installed your experimental setup at the North Pole or some other difficult to reach location and the experiment leader calls you up: Get your a** over here ASAP! The application crashes every two days.😀
Yes this is dramaticized, but only a little. If you want to be sure that your Call Library Node configuration is correct you CAN use the Import Library Wizard (I usually don't), but you still have to review every single function afterwards very carefully to be correct and usually make at least some modifications. And to do that you need to know everything that you also would need to know in order to create the function yourself in the first place.
Your include file you post includes a GH_200vardef.h file which most likely would describe some of the additional datatypes.
As to the tGH200_HANDLE type, yes that is a pointer sized integer as far as the LabVIEW Call Library Node is concerned.
However a quick glance at the header file reveals that is uses rather large structs and even unions. It seems not to use pointers inside structs. So yes it will be possible to create Call Library Nodes to call these functions, and the Import Library Wizard will likely be helpful to take part of the work to create this structs in for of LabVIEW clusters but LabVIEW has nothing that can be used to represent C unions. They are only used for flags but still it will be some extra manual work to create the code to deal with these things.
There are many potential gotchas in this. First the header seems to use unconditional 1 byte packing for all data structures. That is fine for LabVIEW 32-bit for Windows, since LabVIEW uses also 1 byte packing there, but if you ever plan to go to 64-bit, and that time will arrive that you can only use 64-bit applications, then you are kind of screwed since LabVIEW 64-bit uses standard 8 byte alignment. Of course there is always the chance that this DLL doesn't even exist for 64-bit and never will, which would be just as big of a problem if you are eventually being forced to go to 64-bit.
One serious question: How many weeks have you planned to create this driver? And be aware that even after that you will never know if that driver is properly programmed and doesn't cause hidden memory corruptions, if you are not able to fully understand every detail needed to create it from scratch yourself.
