how to build a dll

[Kumar_B]

hi everybody,

                        I have a problem  on creating a dll for my appliction in labview. Anybody give me the suggesstion for creating a dll.

Thanks.

kumar.

[Dennis_Knutson]

If you have a problem, it would help if you explained exactly what the problem is. I'm assuming that you've read the on-line help which has pretty detailed instructions on how to build a dll. If not, that's the first place you should start. I'm also assuming that you actually have the application builder installed.

[Kumar_B]

I have a doubt reg the configuration of the input parameters when LabVIEW builds them into a Dll.

For example,

       F to C Vi has 1 i/p and 1 o/p. I built this VI into a dll. This dll is called by another VI, where it shows 2 inputs F & C. The return type is a 8-byte double. But as of my unserstanding, it should be1 I/P only, ie, degF alone. Am I right? If not, what is the reason for the appearance of the second input degC, when it shoulld have been the output by itself ?

LabVIEW by itself builds the Dll with all the required parameters when we export he VI. So, why does it have the DegC as the second I/P parameter when the connector pane does not have it as an input?

Please explain this confusion to me.

The file with extn .zip is the FtoC Dll. Please change the extn when U use it.

Regards,

Kumar.

[Dennis_Knutson]

I can't open the zip file - it says it's not a vaild archive but I think your problem is with the Call Library Node. When you create the dll, take note of the function prototype that is shown. It probably says 'void FtoC(double degF, double *degC)'. When you configure the Call Liabray Function, the prototype you deine there must match. So, the first parameter is return type and that should be 'void'. You've got the other parameters defined correctly. With the Call Library Node, it creates a pair of connections for each parameter. Since the first parameter is an input, you would wire your control to the left side. The second parameter is an output, so you wire to the right side. In some cases, you have to wire a constant value to the left side as well but not in this case. Your Call Library Function should look like the picture here.

Message Edited by Dennis Knutson on 07-20-2006 09:44 AM