Using ActiveX control in C#

[Big Trev]

Has any one had much luck with this. I have run AXIMP ont the .OCX to create the DLL. Then i have registerd the DLL using REGASM. I add a reference to the DLL, then try to instantiate an object, I get the following error An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in mscorlib.dll Additional information: Catastrophic failure Has anyone any ideas. I have also tried this by just adding a reference to the original .ocx, and letting the IDE to the AXIMP for me. Same problem. Thanks

[Stephane Rodriguez]

Big Trev wrote: I have run AXIMP ont the .OCX to create the DLL. Then i have registerd the DLL using REGASM. These two actions are doing the opposite. If you intend to use an ActiveX control in your C# code, then use the IDE, Toolbox \ customize, and browse your ActiveX component. The ActiveX component will be preinteroped, so you don't need any manual call to aximp.exe (this works in most cases. There are gotcha though). When you drop the component into a form, you'll see whether it gets instantiated or not.

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[Heath Stewart]

As Stephane said, just use the "Add Reference..." and select the COM tab. You almost have the right idea, though. Use aximp.exe to import an ActiveX control and create an interop assembly. DO NOT, however, register it! Regasm.exe is for registering assemblies that contain interop metadata, such as controls that act as ActiveX controls through a CCW (COM-Callable Wrapper). If you use Regasm.exe on the interop assembly generated by from the native ActiveX control, you've just overwritten the registry settings so that the interop assembly is now the target of the CLSID! Any application trying to instantiate your original ActiveX control is now instantiating (unknowingly in almost all cases) the control in the .NET assembly through a CCW. The interop assembly, however, is looking for the actual control and not finding it because it's finding itself! Now, I would hope (and don't remember off the top of my head) that regasm.exe checks to see if the assembly was imported from an ActiveX control. But it if isn't, you need to use "regasm.exe /u myassembly.dll" immediately, and then use "regsvr32.exe myactivex.ocx" to fix the registry problems that are most likely affecting you.

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[Big Trev]

Thanks for the reply. I still can not get it working though. this is the code i am using to create the object. COMMSOCXLib.CommsOCXClass comm = new COMMSOCXLib.CommsOCXClass(); try { comm.Reset(); } catch (System.Runtime.InteropServices.COMException e) { Console.WriteLine(e.ToString()); Console.ReadLine(); } And this is the error i catch. System.Runtime.InteropServices.COMException (0x8000FFFF): Catastrophic failure at System.RuntimeType.ForwardCallToInvokeMember(String memberName, BindingFla gs flags, Object target, Int32[] aWrapperTypes, MessageData& msgData) at COMMSOCXLib.CommsOCXClass.Reset()

[Heath Stewart]

Did you unregister your interop assembly and re-register the actual ActiveX OCX? You might also re-install ActiveX control if it was packed in an installer, since the install might have written more registry entries. It seems as if the actual COM method (remember, the interop assembly is only a Runtime Callable Wrapper (RCW), in which calls are forwarded) is not being called because the forwarding method can't the object to call.

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[Big Trev]

Yep, i did a regasm /u on the interop assembly, and regsvr32 on the ocx. Still no joy. let me know if you fancy having a go with the ocx. I can mail it. it is only 100k. At the moment i an writing a DLL wrapper for the c api that also comes with the product. Thanks Trev