Mqtt python on gpio - using a number value not working

Setup, Configuration and Use Scripts & Rules
1

Hi,
I’ve got openhab2 running on a raspberry pi 3.
To create a pulsed signal on gpio I’m using mqtt to interact with the pins.
The first step is working, I can transmit a switch command via mqtt to change a gpio pin.
I can also transmit a number to my python script.

My actual problem is, that I don’t know how to convert the number 'global_pwm ’ using it anyway in the script.
At the moment my sleep command isn’t changing.
My code:

import paho.mqtt.client as mqtt
import RPi.GPIO as GPIO
import time
from time import sleep

MQTT_HOST = "192.168.4.1"
MQTT_PORT = 1883
MQTT_KEEPALIVE_INTERVAL = 45
MQTT_TOPIC = "raspi3/pin18PWM"
MQTT_TOPIC1 = "raspi3/pin6"
MQTT_TOPIC2 = "raspi3/pin23"

LED1 = 6
LED2 = 23
servoPIN = 18

GPIO.setmode(GPIO.BCM)

GPIO.setup(servoPIN, GPIO.OUT)
GPIO.setup(LED1, GPIO.OUT)
GPIO.setup(LED2, GPIO.OUT)

global_pwm = 2

p = GPIO.PWM(servoPIN, 50) # GPIO 18 als PWM mit 50Hz, 20ms
p.start(50) #

try:
  def on_connect(self,mosq, obj, rc):
     mqttc.subscribe(MQTT_TOPIC, 0)
     mqttc.subscribe(MQTT_TOPIC1, 0)
     print("Connect on "+MQTT_HOST)
  
  def on_message(mosq, obj, msg):
    if (msg.topic == 'raspi3/pin18PWM'):
      global_pwm = float(msg.payload)
      print "Topic: " + str(msg.topic)
      print "message: " + str(msg.payload)
  def on_subscribe(mosq, obj, mid, granted_qos):
          print("Subscribed to Topic: " + 
          MQTT_TOPIC + " with QoS: " + str(granted_qos))
    # Initiate MQTT Client
  mqttc = mqtt.Client()

    # Assign event callbacks
  mqttc.on_message = on_message
  mqttc.on_connect = on_connect
  mqttc.on_subscribe = on_subscribe

    # Connect with MQTT Broker
  mqttc.connect(MQTT_HOST, MQTT_PORT, MQTT_KEEPALIVE_INTERVAL)

    # Continue monitoring the incoming messages for subscribed topic
  #mqttc.loop_forever(): 
  while True:
    mqttc.loop(0.01)
    GPIO.output(LED1,True)
    sleep(global_pwm) 
    mqttc.loop(0.01)
    GPIO.output(LED1,False)
    sleep(global_pwm)
  
except KeyboardInterrupt:  
  # here you put any code you want to run before the program   
  # exits when you press CTRL+C
  p.ChangeDutyCycle(2.5)
  p.stop()
  GPIO.cleanup()

Can anybody help me with this?

Thanks a lot
Chris