diff --git a/bot.py b/bot.py
index 0ed54e1..bd8afb6 100644
--- a/bot.py
+++ b/bot.py
@@ -8,6 +8,10 @@ import logging
 import requests
 import schedule
 
+STATUS_URL = "https://isfswiaiopen.wiai.de?json"
+MESSAGE_URL = "https://api.telegram.org/bot{token}/sendMessage"
+IMAGE_URL = "https://api.telegram.org/bot{token}/sendPhoto"
+
 logging.basicConfig(format='%(asctime)s %(levelname)s %(name)s:%(message)s', level=logging.DEBUG, datefmt="%Y.%m.%d %H:%M:%S")
 log = logging.getLogger(__name__)
 
@@ -15,7 +19,7 @@ def parse_time(string):
 	return datetime.datetime.strptime(string, "%Y-%m-%d %H:%M:%S")
 
 def get_status():
-	status = requests.get("https://isfswiaiopen.wiai.de?json").json()
+	status = requests.get(STATUS_URL).json()
 	status["timestamp"] = parse_time(status['timestamp'])
 	return status
 
@@ -23,21 +27,31 @@ def get_status_text(config, src=get_status):
 	return config["texts"][str(get_status()["doorstate"])]
 
 def post(chats, text, token):
-	url = "https://api.telegram.org/bot{token}/sendMessage".format(token=token)
+	url = MESSAGE_URL.format(token=token)
 	for chat in chats:
 		response = requests.post(url, data={'chat_id': chats[chat], "text": text})
 		log.info("post message: %s", response.status_code)
 
+def has_argument(args, key):
+	return key in args and args[key]
+
+def get_config(args):
+	config = json.load(open(args['config']))
+	if has_argument(args, "interval"):
+		log.info("Overwrite sleep value by argument…")
+		config["sleep"] = args["interval"]
+	return config
+
 def main(args={"config": "settings.json"}):
 	log.info("run once")
-	config = json.load(open(args['config']))
+	config = get_config(args)
 	text = get_status_text(config)
 	post(config['groups'], text, config['token'])
 	post_plot(config)
 
 def loop(args={"config": "settings.json"}):
 	log.info("prepare loop")
-	config = json.load(open(args['config']))
+	config = get_config(args)
 	setup(config)
 	while True:
 		try:
@@ -50,25 +64,32 @@ def do_loop(config):
 	last_state = None
 	while True:
 		log.info("enter loop")
-		changed = False
-		new_state = get_status()
-		if last_state is None:
-			changed = True
-		elif not last_state["doorstate"] == new_state["doorstate"]:
-			changed = True
+		changed = has_changed(last_state)
 		if changed:
-			last_state = new_state
-			text = get_status_text(config, lambda: last_state)
-			post(config["groups"], text, config["token"])
+			last_state = update(new_state)
 		log.info("run pending tasks")
 		schedule.run_pending()
 		log.info("sleep")
 		time.sleep(config['sleep'])
 
+def has_changed(last_state):
+	changed = False
+	new_state = get_status()
+	if last_state is None:
+		changed = True
+	elif not last_state["doorstate"] == new_state["doorstate"]:
+		changed = True
+	return changed
+
+def update(state):
+	text = get_status_text(config, lambda: state)
+	post(config["groups"], text, config["token"])
+	return state
+
 def post_plot(config):
 	from plot import get_plot
 	with NamedTemporaryFile() as target:
-		image_url = 'https://api.telegram.org/bot{token}/sendPhoto'.format(token=config['token'])
+		image_url = IMAGE_URL.format(token=config['token'])
 		photo, last = get_plot(target)
 		files = {'photo': photo}
 		if last + datetime.timedelta(days=1) < datetime.datetime.today():
@@ -76,7 +97,7 @@ def post_plot(config):
 			return
 		for chat in config['groups']:
 			files['photo'].seek(0)
-			values = {"chat_id":config['groups'][chat]}
+			values = {"chat_id": config['groups'][chat]}
 			r = requests.post(image_url, files=files, data=values)
 			log.info("post photo: %s", r.status_code)
 
@@ -87,6 +108,7 @@ if __name__ == "__main__":
 	parser = argparse.ArgumentParser(description="DoorStateBot")
 	parser.add_argument("--config", "-c", default="settings.json", help="Configuration file")
 	parser.add_argument("--loop", "-l", action="store_true", help="Loop")
+	parser.add_argument("--interval", "-i", help="Interval")
 	args = parser.parse_args()
 	if args.loop:
 		loop(vars(args))