Hello Here's my problem. DLL looked always magic to me, so I tried to work with them to see how it works. I wrote a DLL in Labwindow/CVI 6.0 and my first fonction had the following prototype
extern int __cdecl MyDLL_Init (int In1,char *Out2); I did'nt exactly know why using a C type declaration or a standard one but the I followed a typical example found in the Developer zone. Actually my function had one integer input (In1) and two output: a status Integer and a C string parameter. I called the function in Labview 6i following the example given and I was surprised that everything worked the first time. I wanted to add another output string to my function, so I changed the prototype extern int __cdecl MyDLL_Init (int In1,char *Out2,char *Out3); I changed the configuration in Labview Call Library Function and then Labview crashed all the time. I tried to call the DLL in a CVI program and everything went well. I came back to Labview and it crashed again. I came back to the first prototype and it worked well. I thought it might be the fact that Labview does not use C type string but it worked fine with only one output string, so it does do the conversion if the String Format is correctly chosen in the configuration. Finally I just changed the convention from cdecl to stdcall and everything worked well. As a mechanical engineer, I am more a self-taught programmer and most of the time I change everything till it works without understanding very well but I wonder why this happens like this. Thank you very much Louis
