Multiple ESP8266 subscribe to one RPI 3

Question

i have problem to subscribe 2 (and more) ESP8266 to one RPi3 broker. I used:

import paho.mqtt.client as mqtt
import datetime

mqtt_topics = ["esp8266-1", "esp8266-2"]

def on_connect(client, userdata, flags, rc):
    print("Connected with result code "+str(rc))

    for topic in mqtt_topics:
     client.subscribe(topic)

def on_message(client, userdata, msg):
    print(datetime.datetime.now())
        print(str(msg.topic)+" "+str(msg.payload))

client = mqtt.Client()
client.on_connect = on_connect
client.connect('localhost', 1883, 60)

try:
    for topic in mqtt_topics:
        client.on_message = on_message
    client.loop_forever()
except KeyboardInterrupt:
        print("CTRL-C: Terminating program.")

It works but ony to 1 esp. If i connect esp8266-1 it checks it values, then i connect esp8266-2 to have its values and esp8266-1 is no longer available (even if i turn of esp8266-2).

How to subscribe both esp8266? I only can have one of them at time.

Answer 1

The code needs few changes:

import paho.mqtt.client as mqtt
import datetime

mqtt_topics = [("esp8266-1",0), ("esp8266-2",0)]

def on_connect(client, userdata, flags, rc):
  print("Connected with result code "+str(rc))
  client.subscribe(mqtt_topics)

def on_message(client, userdata, msg):
  print(datetime.datetime.now())
  print(str(msg.topic)+" "+str(msg.payload))

client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message
client.connect('localhost', 1883, 60)

try:
  client.loop_forever()
except KeyboardInterrupt:
  print("CTRL-C: Terminating program.")

But if one client works and a second forces the first to disconnect then it sounds like you have the same clientID for both clients. clientIDs need to be unique for all client.