diff --git a/doorbell/klingel_sender_nano_serial/doorbell.py b/doorbell/klingel_sender_nano_serial/doorbell.py
index 232852d..b1fe600 100644
--- a/doorbell/klingel_sender_nano_serial/doorbell.py
+++ b/doorbell/klingel_sender_nano_serial/doorbell.py
@@ -1,6 +1,6 @@
 # https://www.instructables.com/id/Arduino-Python-Communication-via-USB/
-# in rc.local:
-#   su tilman -c 'python3 /media/hd/admin/doorbell/doorbell.py >> /media/hd/admin/doorbell/doorbell.log 2>&1 &'
+# in /etc/systemd/system/startup-commands.service (s. https://www.nodebucket.de/index.php/apps/cms_pico/pico/server/setup):
+#   ExecStart = su tilman -c 'python3 /media/hd/admin/doorbell/doorbell.py >> /media/hd/admin/doorbell/doorbell.log 2>&1 &'
 
 import serial
 import urllib.request
@@ -28,21 +28,21 @@ while True:
             data = data.decode('utf8')
         except (UnicodeDecodeError) as ude:
             logger.error(ude)
+        else:
+            logger.info(data)
+        
         if (data == 'RING'):
             try:
                 response = urllib.request.urlopen('http://192.168.178.60/bell/on', timeout=5).read().decode('utf-8')
 
                 # send MQTT
                 headers = {
-#                    "Authorization": "Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJjYjY5NjA5NmY0N2E0NmZlOGEzYjczOGYzYmUzOTk5ZSIsImlhdCI6MTY2MTM0NDgxOSwiZXhwIjoxOTc2NzA0ODE5fQ.z9fzbVOA1Pbur3Zb07481n-SoYesj8cetw-CX6WPmTs",
-                     "Content-Type": "application/json"
+                    "Authorization": "Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJjYjY5NjA5NmY0N2E0NmZlOGEzYjczOGYzYmUzOTk5ZSIsImlhdCI6MTY2MTM0NDgxOSwiZXhwIjoxOTc2NzA0ODE5fQ.z9fzbVOA1Pbur3Zb07481n-SoYesj8cetw-CX6WPmTs",
+                    "Content-Type": "application/json"
                 }
                 data = json.dumps({'payload': 'RING', 'topic': 'lewe/doorbell', 'retain': 'False'}).encode('utf8')
-                request = urllib.request.Request("localhost:8123/api/services/mqtt/publish", data, headers)
-#                request = urllib.request.Request("https://www.nodebucket.de:8123/api/services/mqtt/publish", data, headers)
+                request = urllib.request.Request("https://www.nodebucket.de:8123/api/services/mqtt/publish", data, headers)
                 response = urllib.request.urlopen(request)
-            except Exception as err:
+            except Exception:
                 logger.error("Could not ring doorbell")
-                time.sleep(300)
-            else:
-                logger.info(data)
+                time.sleep(300)
\ No newline at end of file