MyStruct sss = new MyStruct();
object o = sss;
...
ByteArrayToStructure(bytearray, ref o);
Text = sss.cmdname;
Text = ((MyStruct)o).cmdname;

void ByteArrayToStructure(byte[] bytearray, ref object obj)
        {
            int len = Marshal.SizeOf(obj);
            IntPtr i = Marshal.AllocHGlobal(len);
            Marshal.Copy(bytearray, 0, i, len);
            obj = Marshal.PtrToStructure(i, obj.GetType());
            Marshal.FreeHGlobal(i);
        }