public static XMLConfiguration Load()
        {
            if (__instance != null)
            {
                return(__instance);
            }

            if (!File.Exists(ConfigurationFilePath))
            {
                throw new FileNotFoundException(ConfigurationFilePath);
            }
            XMLConfiguration c   = new XMLConfiguration();
            XmlDocument      xml = new XmlDocument();

            xml.Load(ConfigurationFilePath);

            // wczytanie interfejsów
            List <RS232Configuration> interfaces = new List <RS232Configuration>();
            XmlNodeList nodes = xml.SelectNodes("/configuration/interfaces/interface");

            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    RS232Configuration interf = RS232Configuration.Load(node);
                    interfaces.Add(interf);
                }
            }
            c.Interfaces = interfaces.ToArray();

            // wczytanie urządzeń z LCD
            List <LCDDevice> lcdDevices = new List <LCDDevice>();

            nodes = xml.SelectNodes("/configuration/lcdDevices/lcdDevice");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    LCDDevice lcdDevice = LCDDevice.Load(node, interfaces);
                    if (lcdDevice != null)
                    {
                        lcdDevices.Add(lcdDevice);
                    }
                }
            }
            c.LCDDevices = lcdDevices.ToArray();

            // wczytanie LCD
            List <RS232LCD> lcds = new List <RS232LCD>();

            nodes = xml.SelectNodes("/configuration/lcds/lcd");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    RS232LCD lcd = RS232LCD.Load(lcdDevices, node);
                    if (lcd != null)
                    {
                        lcds.Add(lcd);
                    }
                }
            }
            c.LCDs = lcds.ToArray();

            // wczytanie obszarów LCD
            List <LCDArea> areas = new List <LCDArea>();

            nodes = xml.SelectNodes("/configuration/lcdAreas/area");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    LCDArea area = new LCDArea(node, new LCDSet(lcds));
                    areas.Add(area);
                }
            }
            c.Areas = areas.ToArray();

            // wczytanie urządzeń z LED
            List <LEDDevice> ledDevices = new List <LEDDevice>();

            nodes = xml.SelectNodes("/configuration/ledDevices/ledDevice");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    LEDDevice ledDevice = LEDDevice.Load(node, interfaces);
                    if (ledDevice != null)
                    {
                        ledDevices.Add(ledDevice);
                    }
                }
            }
            c.LEDDevices = ledDevices.ToArray();

            // wczytanie LED
            List <LED> leds = new List <LED>();

            nodes = xml.SelectNodes("/configuration/leds/led");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    LED led = LED.Load(node, ledDevices);
                    if (led != null)
                    {
                        leds.Add(led);
                    }
                }
            }
            c.LEDs = leds.ToArray();

            // wczytanie obszarów LED
            List <LEDGroup> ledGroups = new List <LEDGroup>();

            nodes = xml.SelectNodes("/configuration/leds/leds");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    LEDGroup ledGroup = LEDGroup.Load(node, leds);
                    if (ledGroup != null)
                    {
                        ledGroups.Add(ledGroup);
                    }
                }
            }
            c.LEDGroups = ledGroups.ToArray();

            // wczytanie urządzeń z 7-LED
            List <LEDDisplayDevice> ledDisplayDevices = new List <LEDDisplayDevice>();

            nodes = xml.SelectNodes("/configuration/ledDisplayDevices/ledDisplayDevice");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    LEDDisplayDevice ledDisplayDevice = LEDDisplayDevice.Load(node, interfaces);
                    if (ledDisplayDevice != null)
                    {
                        ledDisplayDevices.Add(ledDisplayDevice);
                    }
                }
            }
            c.LEDDisplayDevices = ledDisplayDevices.ToArray();

            // wczytanie 7-LED
            List <LEDDisplay> ledDisplays = new List <LEDDisplay>();

            nodes = xml.SelectNodes("/configuration/ledDisplays/ledDisplay");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    LEDDisplay ledDisplay = LEDDisplay.Load(node, ledDisplayDevices);
                    if (ledDisplay != null)
                    {
                        ledDisplays.Add(ledDisplay);
                    }
                }
            }
            c.LEDDisplays = ledDisplays.ToArray();

            // wczytanie obszarów 7-LED
            List <LEDDisplayGroup> ledDisplayGroups = new List <LEDDisplayGroup>();

            nodes = xml.SelectNodes("/configuration/ledDisplays/ledDisplays");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    LEDDisplayGroup ledDisplayGroup = LEDDisplayGroup.Load(node, ledDisplays);
                    if (ledDisplayGroup != null)
                    {
                        ledDisplayGroups.Add(ledDisplayGroup);
                    }
                }
            }
            c.LEDDisplayGroups = ledDisplayGroups.ToArray();

            // wczytanie słownika dla wyświetlaczy 7-segmentowych
            XmlNode dictionaryNode = xml.SelectSingleNode("/configuration/ledDisplaysDictionary");

            c.LEDDisplaysDictionary = LEDDisplaysDictionary.Load(dictionaryNode);

            // wczytanie urządzeń Keys
            List <KeysDevice> keysDevices = new List <KeysDevice>();

            nodes = xml.SelectNodes("/configuration/keysDevices/keysDevice");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    KeysDevice keysDevice = KeysDevice.Load(node, interfaces);
                    if (keysDevice != null)
                    {
                        keysDevices.Add(keysDevice);
                    }
                }
            }
            c.KeysDevices = keysDevices.ToArray();

            // wczytanie keys
            List <Key> keys = new List <Key>();

            nodes = xml.SelectNodes("/configuration/keys/key");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    Key key = Key.Load(node, keysDevices);
                    if (key != null)
                    {
                        keys.Add(key);
                    }
                }
            }
            c.Keys = keys.ToArray();

            // wczytanie encoders
            List <Encoder> encoders = new List <Encoder>();

            nodes = xml.SelectNodes("/configuration/encoders/encoder");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    Encoder encoder = Encoder.Load(node, keysDevices);
                    if (encoder != null)
                    {
                        encoders.Add(encoder);

                        // przypisanie enkoderów do wejść (wykrywanie szybkiego kręcenia)
                        foreach (Key key in c.Keys)
                        {
                            if (key.KeysDevice == encoder.KeysDevice)
                            {
                                if (key.Index == encoder.LeftIndex || key.Index == encoder.RightIndex)
                                {
                                    key.Encoder = encoder;
                                }
                            }
                        }
                    }
                }
            }
            c.Encoders = encoders.ToArray();

            // wczytanie stepper motors
            List <StepperDevice> stepperDevices = new List <StepperDevice>();

            nodes = xml.SelectNodes("/configuration/stepperDevices/stepperDevice");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    StepperDevice stepperDevice = StepperDevice.Load(node, interfaces);
                    if (stepperDevice != null)
                    {
                        stepperDevices.Add(stepperDevice);
                    }
                }
            }
            c.StepperDevices = stepperDevices.ToArray();

            // wczytanie servo devices
            List <ServoDevice> servoDevices = new List <ServoDevice>();

            nodes = xml.SelectNodes("/configuration/servoDevices/servoDevice");
            if (nodes != null && nodes.Count > 0)
            {
                foreach (XmlNode node in nodes)
                {
                    ServoDevice servoDevice = ServoDevice.Load(node, interfaces);
                    if (servoDevice != null)
                    {
                        servoDevices.Add(servoDevice);
                    }
                }
            }
            c.ServoDevices = servoDevices.ToArray();


            __instance = c;

            return(__instance);
        }