I have got a C DLL and try to transfer Paramter between VB.net and DLL:

Deklaration in VB:

    <DllImport("can.dll", CallingConvention:=CallingConvention.StdCall)>
    Public Shared Function TransmitSerCanCmd(cmd As UInteger, ByRef pSrcData As Byte(), numScrData As UInteger) As Boolean
    End Function

 <DllImport("can.dll")>
    Public Shared Function ReadSerCanDllVersionInfo(ByRef lpszVersionInfo As String) As UInteger
    End Function

All information about can.dll I have is:

BOOL CALLBACK                   /* successful (TRUE) / failed (FALSE) */
 TransferSerCanSrvData                      /* Transfer service data */
  (UINT srv,                    /* data service (<=127) */
   void *pDstData,              /* data destination for data read from server */
   UINT numDstData,                 /* number of data to read from server (<=8) */
   void *pSrcData,              /* data source for data sent to server */
   UINT numSrcData);                /* number of data to send to server (<=8) */

BOOL CALLBACK                       /* successful (TRUE) / failed (FALSE) */
 ReadSerCanDllVersionInfo           /* Read SerCAN protocol dynamic link library version and info */
  (LPSTR lpszVersionInfo);          /* version and info string (! min. 80 characters) */

In VB.Net I wrote this test:

        Dim x1(7) As Byte
        Dim x2(3) As Byte
        Dim b1,b2 as boolean

        x2(0) = 1
        x2(1) = 0
        x2(2) = 55

        b1 = TransferSerCanSrvData(1, x1, 2, x2, 2)
       
        Dim s1 As String
        a2 = ReadSerCanDllVersionInfo(s1)

Unfortunately this doesn’t work. I don’t get any information back in Byte Array.
String reference is also not working. Can anybody help please what is missing here? Thanks.

I alredy tried to use other data type without success.