[RESOLVED] VB6 - Unsigned data type (Can I trick?)

[LaVolpe]

Hey got another idea if any of the above don't work. I am guessing that your OPC control is checking the variant type of the passed variant and if it isn't UI4 then it is ignoring it. So, how about forcing the issue with CopyMemory API...

Dim vData As Variant, vType As Integer
vType = &H2000 Or 19 ' array of UI4
vData = CVar(Vals())
' write to the variant structure what type of data it contains
CopyMemory ByVal VarPtr(vData), vType, 2&
' now the variant thinks it is UI4; how now?
ASyncItemValues(1) = vData

If it works, UI2 is &H2000 Or 18
Listing of Variant Type codes


Edited: I see I pretty much repeated what Merri posted. Even though VB can't use the vData variant while it thinks it is UI4, your OPC should be able to. If the vData variant needs to be read by your VB app, then you'd have to change the UI4 to simply I4 which is &H2000 Or 3 for a an array of longs; then you'd be able to read the data back using VB.