DECLARE SHORT DeviceIoControl IN WIN32API ; INTEGER hDeviceHandle, ; INTEGER dwIOControlCode, ; STRING lpInBuffer, ; INTEGER dwInBufferSize, ; STRING lpOutBuffer, ; INTEGER dwOutBufferSize, ; INTEGER @ lpdwBytesReturned, ; STRING lpOverlappedYou'll need the MSDN documentation and detailed knowledge about the type of device you're trying to manipulate to make use of the API call.