{"Specified array was not of the expected type."}

Hi,

I'm trying to interface between OPC (OLE for Process Control) and C# using Siemens' OPCAutomationDAServer (comes with a package called PC Access).

Now, there are some VB6 examples, and indeed they work perfectly fine.

There are many such occurances of the above message.

One has the following signatures:

VB6:
AddItems(x as int, y() as string, z() as long, k() as string, l() as string...)

from C# the signature reads as :
AddItems(int x, ref Array y, ref Array z....)

I tried using the same array types that are in use in VB6, and I tried arrays of objects and I tried System.Array.CreateInstance(). Nothing worked.

If someone can shed light on this, I'd really appreciate this!

Thanks in advance

Answer this question

{"Specified array was not of the expected type."}

WalidM
The Siemens app would expect an SAFEARRAY(BSTR). Hmm, COM interop should take care of that but be sure to pass a String[]...
Karin P
I ran into a similar problem. Try casting the string array to an object then passing the object by ref. e.g.,

Code Block

string[] sArr = new string[]{"abc", "def", "ghi"};

object o = (object)sArr;

AutomationObjectClass.SomeMethod(ref o);

If SomeMethod changes the contents of array elements you should be able to read the modified values with:

Code Block

string[] newArr = (string[])o;

// read modified elements in newArr[]
{"Specified array was not of the expected type."}

Answer this question