diff --git a/app.py b/app.py
index 08606c5..b955f02 100644
--- a/app.py
+++ b/app.py
@@ -4,26 +4,35 @@ from flask import request
 from flask_api import FlaskAPI
 import RPi.GPIO as GPIO
 
-LEDS = {"green": 16, "red": 18}
-GPIO.setmode(GPIO.BOARD)
-GPIO.setup(LEDS["green"], GPIO.OUT)
-GPIO.setup(LEDS["red"], GPIO.OUT)
+from xml_reader import Xml_reader
+from interface_handler import Interface_handler
+
+xml_reader = Xml_reader('XML/config.xml','XML/config.xsd')
+interface_handler = Interface_handler(xml_reader)
+
+device_names = xml_reader.get_device_names()
 
 app = FlaskAPI(__name__)
 
 @app.route('/', methods=["GET"])
 def api_root():
     return {
-           "led_url": request.url + "led/(green | red)/",
-             "led_url_POST": {"state": "(0 | 1)"}
+           "device_url": request.url + "device/<device_name>",
+             "device_url_POST": {"output": "<value>"}
                  }
   
-@app.route('/led/<color>/', methods=["GET", "POST"])
-def api_leds_control(color):
+@app.route('/device/<device_name>/', methods=["GET", "POST"])
+def api_leds_control(device_name):
     if request.method == "POST":
-        if color in LEDS:
-            GPIO.output(LEDS[color], int(request.data.get("state")))
-    return {color: GPIO.input(LEDS[color])}
+        # if color in LEDS:
+        #     GPIO.output(LEDS[color], int(request.data.get("state")))
+        try:
+            response = interface_handler.write(device_name,request.data.get("output"))
+            return {'output': response}
+        except Exception as e:
+            return {'error': str(e)}
+    # return {color: GPIO.input(LEDS[color])}
+    return {'state': interface_handler.read(device_name)}
 
 if __name__ == "__main__":
     app.run(port=8080,host="0.0.0.0")
diff --git a/interface_handler.py b/interface_handler.py
index a3570e8..78b1c30 100644
--- a/interface_handler.py
+++ b/interface_handler.py
@@ -95,9 +95,9 @@ class Interface_handler:
         pins = port_info["pins"]
 
         for pin in self.xml_reader.get_port(device_name)["pins"]:
-            if protocol == "DI":
+            if protocol == "DI" or "DO":
                 returnValues.update({
-                    pin:GPIO.input(self.Pin[pin].value)
+                    pin : GPIO.input(self.Pin[pin].value)
                 })
             else: #throw error for protocols without write functionality
                 raise ValueError("you can not read from device %s" % device_name)
@@ -105,19 +105,21 @@ class Interface_handler:
 
 
     def write(self, device_name:str, value):
-        """writes a value to all the pins of a device
+        """writes an output to a given device
 
         Args:
-            device_name (string): name of the device 
-            value (float): the value to be written
+            device_name (str): the name of the relevant device
+            value (<type depends on protocol>): the value to be written
 
         Raises:
-            NameError: device not found in config.xml
-            TypeError: value has wrong type
+            NameError: the device name could not be found in the config.xml
+            TypeError: the given Value has the wrong type for the protocol  
+            ValueError: the value cannot be written to the device
 
         Returns:
-            value if everything went well, None otherwise
+            <type depends on protocol>: value if everything worked correctly
         """
+
         #check device_name is valid
         if self.xml_reader.get_port(device_name) == None:
             raise NameError('the device with the name %s is unknown' % device_name)
@@ -129,10 +131,11 @@ class Interface_handler:
         for pin in self.xml_reader.get_port(device_name)["pins"]:
             if protocol == "DO":
                 #type check input value
-                if not value in [GPIO.HIGH,GPIO.LOW]:
-                    raise ValueError("value must be GPIO.HIGH or GPIO.LOW")
+                if not value in ['0','1']:
+                    raise TypeError("value must be '0' or '1'")
+                value = GPIO.HIGH if value == '1' else GPIO.LOW
                 GPIO.output(self.Pin[pin].value,value)
-                return value
+                return GPIO.input(self.Pin[pin].value)
             else: #throw error for protocols without write functionality
                 raise ValueError("you cannot write to device %s" % device_name)