Hi I am trying to write a wrapper around the USBXpress driver SiUSBXp.dll

I have successfully been able to talk to one of the functions within this driver but I am unable to get the SI_Write function to work. below is the wrapper funciton

// function SI_Write (Handle: THandle; Buffer: LPVOID; NumBytesToWrite:
    // dword; var NumBytesWritten: dword; lpOverlapped: POverlapped):
    // TSI_Status; stdcall external 'SiUSBXp.dll';
    public static long SI_Write(Handle handle, Pointer Buffer_LPVOID, UInt32 int32, Pointer pointer,
            Void void1) {
        Function add = USBXPRESS_LIB.getFunction("SI_Write");
        ULongInt result = new ULongInt();
        Parameter[] params = { handle, Buffer_LPVOID, int32, int32, void1 };
        add.invoke(result, params);
        // add.invoke(result,Handle_THandle,Buffer_LPVOID,NumBytesToWrite_dword,NumBytesWritten_dword,lpOverlapped_POverlapped);
        return result.getValue();
    }

and here is how I call this function within my code.

public void write(String command) throws USBXpressException {
        AnsiString cmd = new AnsiString(command);
        Pointer cmdp = new Pointer(cmd);
        UInt32 bytesWritten = new UInt32();
        UInt32 numberOfBytesToWrite = new UInt32(cmdp.getAlignedLength());
        long  ss;
        ss=USBXpressDLL.SI_Write(this.handle, new Pointer.OutOnly(cmdp), numberOfBytesToWrite, new Pointer(bytesWritten), new Pointer.Void(0));
          //assert(bytesWritten=dword(length(s)));
          //this.write=bytesWritten;
          if(ss!=USBXpressDLL.SI_SUCCESS){ throw new USBXpressException("Error Writing");}
    }

the command that I am sending requires to have a chr 13 value sent at the end I am having a feeling that the driver is looking for this character.

when I look at the pointer size it does not reflect the orginal string size of the command being sent.

What am I doing wrong?

I have done some more debugging and have found that the code is returning and error of Invalid parameter so the jniwrapper is calling the function correctly but I am passing an invalid parameter.

how do I find out what parameter is incorrect

here is a excert from the SiUSBXp.dll programers guide

I am sure i have the first 4 parameters setup correctly but am not sure how to represent the 5 param. (This param is always set to nil )

Any suggestions?