Conditional DLL call

[cosborne]

I'm new to using external code in LabView so I might be missing something obvious.

Is there a way to check for the presence of a DLL before making the call? How can you avoid an error (or catch the error) when a DLL is missing? The "Call Library Function Node" doesn't seem to have any way of handling the error. I'm using LV7.0

[cosborne]

I'm new to using external code in LabView so I might be missing something obvious.

Is there a way to check for the presence of a DLL before making the call? How can you avoid an error (or catch the error) when a DLL is missing? The "Call Library Function Node" doesn't seem to have any way of handling the error. I'm using LV7.0

[Dan DeFriese]

Finding the *.dll is not a problem (you can search for it with file I/O).

However, if the file can't be found when the VI is loaded, it will break whether or not you ever call the interface node. I've never tried it, but perhaps using dynamic VIs could allow you to get around this.

[Dan DeFriese]

Finding the *.dll is not a problem (you can search for it with file I/O).

However, if the file can't be found when the VI is loaded, it will break whether or not you ever call the interface node. I've never tried it, but perhaps using dynamic VIs could allow you to get around this.

[Rolf Kalbermatter]

QUOTE (Dan DeFriese @ Jan 14 2009, 03:02 PM)

Finding the *.dll is not a problem (you can search for it with file I/O).

However, if the file can't be found when the VI is loaded, it will break whether or not you ever call the interface node. I've never tried it, but perhaps using dynamic VIs could allow you to get around this.

In LabVIEW 8.5 you can configure the Call Library node to get a path that receives the DLL to call at runtime. Before LabVIEW 8.5 you have indeed to encapsulate all calls to DLLs that might be not available into VIs that get called dynamically through VI server. You can load the VI with an Open Instrument Node and either check its execution state or directly try to call it through the Call By Reference Node. Call by Reference will return an error if the VI was not executable (which it will not be if it could not resolve a DLL call).

Rolf Kalbermatter

[Rolf Kalbermatter]

QUOTE (Dan DeFriese @ Jan 14 2009, 03:02 PM)

Finding the *.dll is not a problem (you can search for it with file I/O).

However, if the file can't be found when the VI is loaded, it will break whether or not you ever call the interface node. I've never tried it, but perhaps using dynamic VIs could allow you to get around this.

In LabVIEW 8.5 you can configure the Call Library node to get a path that receives the DLL to call at runtime. Before LabVIEW 8.5 you have indeed to encapsulate all calls to DLLs that might be not available into VIs that get called dynamically through VI server. You can load the VI with an Open Instrument Node and either check its execution state or directly try to call it through the Call By Reference Node. Call by Reference will return an error if the VI was not executable (which it will not be if it could not resolve a DLL call).

Rolf Kalbermatter

[TomLu]

I made a small toolkit called LVDynaCall. That allow you call DLL dynamic in LabVIEW, you may want have a try on this.

http://code.google.com/p/lvdynacall/

QUOTE (cosborne @ Jan 15 2009, 01:04 AM)

I'm new to using external code in LabView so I might be missing something obvious.

Is there a way to check for the presence of a DLL before making the call? How can you avoid an error (or catch the error) when a DLL is missing? The "Call Library Function Node" doesn't seem to have any way of handling the error. I'm using LV7.0

[TomLu]

I made a small toolkit called LVDynaCall. That allow you call DLL dynamic in LabVIEW, you may want have a try on this.

http://code.google.com/p/lvdynacall/

QUOTE (cosborne @ Jan 15 2009, 01:04 AM)

I'm new to using external code in LabView so I might be missing something obvious.

Is there a way to check for the presence of a DLL before making the call? How can you avoid an error (or catch the error) when a DLL is missing? The "Call Library Function Node" doesn't seem to have any way of handling the error. I'm using LV7.0

[Dan DeFriese]

QUOTE (rolfk @ Jan 14 2009, 05:00 PM)

In LabVIEW 8.5 you can configure the Call Library node to get a path that receives the DLL to call at runtime.

Thanks for pointing this out!

[Dan DeFriese]

QUOTE (rolfk @ Jan 14 2009, 05:00 PM)

In LabVIEW 8.5 you can configure the Call Library node to get a path that receives the DLL to call at runtime.

Thanks for pointing this out!

[crelf]

QUOTE (TomLu @ Jan 14 2009, 07:56 PM)

I made a small toolkit called LVDynaCall. That allow you call DLL dynamic in LabVIEW, you may want have a try on this.

Note: this toolkit is currently under consideration in the http://forums.lavag.org/downloads.html' target="_blank">LAVA Code Repository queue.

[crelf]

QUOTE (TomLu @ Jan 14 2009, 07:56 PM)

I made a small toolkit called LVDynaCall. That allow you call DLL dynamic in LabVIEW, you may want have a try on this.

Note: this toolkit is currently under consideration in the http://forums.lavag.org/downloads.html' target="_blank">LAVA Code Repository queue.