diff --git a/interface_handler.py b/interface_handler.py
new file mode 100644
index 0000000..269f950
--- /dev/null
+++ b/interface_handler.py
@@ -0,0 +1,108 @@
+from enum import Enum
+from xml_reader import Xml_reader
+import RPi.GPIO as GPIO
+
+class interface_handler:
+    """handles the access to the various interfaces (e.g. GPIO)
+    """
+
+    class Pin(Enum):
+        """list of all usable pins
+
+        enables restricting methods to these pins
+        """
+        GIO_2 = 3
+        GIO_3 = 5
+        GIO_4 = 7
+        GIO_5 = 29
+        GIO_6 = 31
+        GIO_7 = 26
+        GIO_8 = 24
+        GIO_9 = 21
+        GIO_10 = 19
+        GIO_11 = 23
+        GIO_12 = 32
+        GIO_13 = 33
+        GIO_14 = 8
+        GIO_15 = 10
+        GIO_16 = 36
+        GIO_17 = 11
+        GIO_18 = 12
+        GIO_19 = 35
+        GIO_20 = 38
+        GIO_21 = 40
+        GIO_22 = 15
+        GIO_23 = 16
+        GIO_24 = 18
+        GIO_25 = 22
+        GIO_26 = 37
+        GIO_27 = 13
+
+    def __init__(self, xml_reader):
+        """inits the interface_handler
+        """
+        if not isinstance(xml_reader, Xml_reader):
+            raise TypeError('xml_reader must be an instance of XML_reader')
+        self.xml_reader = xml_reader
+        self.init_gpio()
+
+    def init_gpio(self):
+        """initialises the GPIO pins
+        """
+        GPIO.setmode(GPIO.BOARD)
+        for device_name in self.xml_reader.get_device_names():
+            protocol, pins in self.xml_reader.get_port(device_name)
+            for pin in pins:
+                if protocol == "AI" or "DI":
+                    GPIO.setup(self.Pin(pin),GPIO.IN)
+                elif protocol == "AO" or "DO":
+                    GPIO.setup(self.Pin(pin),GPIO.OUT)
+                else:
+                    raise NotImplementedError('the protocol of the device %s is not implemented' % device_name)
+                
+
+    def read(self, device_name):
+        """reads the current value from the pins of one device
+
+        Args:
+            device_name (string): the name of the device
+
+        Raises:
+            NameError: the device cannot be found in the config.xml
+
+        Returns:
+            dict:  {'pin': 'value'}
+        """
+        if self.xml_reader.get_port(device_name) == None:
+            raise NameError('the device with the name %s is unknown' % device_name)
+        returnValues = dict()
+        protocol, pins = self.xml_reader.get_port(device_name)
+        if not protocol == "AI" or "DI":
+            raise ValueError("you can not read from device %s" % device_name)
+        for pin in self.xml_reader.get_port(device_name)["pins"]:
+            returnValues.update({
+                pin,
+                GPIO.read(self.Pin(pin))
+            })
+        return returnValues
+
+    def write(self, device_name, value):
+        """writes a value to all the pins of a device
+
+        Args:
+            device_name (string): name of the device 
+            value (float): the value to be written
+
+        Raises:
+            NameError: device not found in config.xml
+            TypeError: value has wrong type
+        """
+        if self.xml_reader.get_port(device_name) == None:
+            raise NameError('the device with the name %s is unknown' % device_name)
+        if not isinstance(value,float):
+            raise TypeError('the value to write must be of type float')
+        protocol, pins = self.xml_reader.get_port(device_name)
+        if not protocol == "AO" or "DO":
+            raise ValueError("you cannot write to device %s" % device_name)
+        for pin in self.xml_reader.get_port(device_name)["pins"]:
+            GPIO.write(self.Pin(pin,value))
\ No newline at end of file
diff --git a/xml_reader.py b/xml_reader.py
index e9dedd2..7f4f45f 100644
--- a/xml_reader.py
+++ b/xml_reader.py
@@ -1,6 +1,6 @@
 import xml.etree.ElementTree as ET
 
-class xml_reader:
+class Xml_reader:
     """ reader for the XML configuration """
 
     def __init__(self, path):