I have written the following piece of C# testing code and the results are confusing. Please help.
int cardNr = VM140API.OpenDevice();
[color=#408040]//result is '0' i.e the connection to card 0 is opened. We're still OK![/color]
bool connected = VM140API.Connected(cardNr);
[color=#408000] //as expected the result is 'true'.[/color]
[color=#408000]//Now I close the devices[/color]
VM140API.CloseDevices();
connected = VM140API.Connected(cardNr);
[color=#408000]//as expected the result is 'false' because the connections were closed[/color]
[color=#408000]//Let us open the connection again[/color]
cardNr = VM140API.OpenDevice();
[color=#BF0000]//NOW HERE I AM CONFUSED. Why is the result of cardNr = -1? If the connection to all devices were closed, should this value not be '0'?[/color]
connected = VM140API.Connected(cardNr);
[color=#BF0000] //the result is 'true' here. Huh? How can the card with nr '-1' be connected?[/color]
This results look strange indeed.
According to the OpenDevice documentation:
Return value -1 indicates that all K8061 cards are opened.
Return value -2 indicates that no card was found.
I did a quick test with the Delphi version and everything seems to work OK.
BTW: Are you using the K8061.DLL or the K8061_C.DLL ?
Have you downloaded the latest DLL v2.0.0 from the Velleman downloads page?
The download package is: k8061_vistapack_2007v1.zip
It includes new driver, example programs and the latest DLL version.
I see I have an older version of the K8061.DLL. I have downloaded the newer one and will let you know.
By the way. The Delphi demo does not have a ‘CloseDevices’ button, but executes the command when you exit the application. When you then re-start the application then everything works fine. I have the same behavior with my app. If I exit the app and re-start it also works fine, but I have Connect and Disconnect buttons in my app and then it does not work OK i.e. I am not exiting the application just disconnecting and re-connecting.
But let me try with the updated drive first. Hope this is the issue…
[quote]The Delphi demo does not have a ‘CloseDevices’ button, but executes the command when you exit the application.[/quote] Yes, normally the CloseDevices() is used only when you exit the program.
To be more specific: I actually modified the Delphi demo and added there a Close button.
Pressing the Close disconnected the card and I got return FALSE from the function Connected(CardAddress) .
Pressing the Connect button, reconnected the card and I got TRUE from this function.
[quote]I have Windows XP and use K8061. Should I use K8061_C instead.[/quote]I think you can use K8061.DLL as well.
BTW: I have not much experience in C#. It would be nice if you can post your code or code snippets to this forum. Especially the section VM140API may be interesting starting point for new C# users who like to control the K8061 from within C# application…
