Ok so I managed to make it works using a specific MQ135 sketch, I thought the one in the examples folder was compatible with a MQ135...

But, even if now I have readings, I do not see them in Domoticz.
Something wrong on the Domoticz side ? but what ?

16 MCO:BGN:INIT NODE,CP=RNNNA---,REL=255,VER=2.3.1
26 TSM:INIT
27 TSF:WUR:MS=0
33 TSM:INIT:TSP OK
35 TSF:SID:OK,ID=42
37 TSM:FPAR
73 TSF:MSG:SEND,42-42-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
679 TSF:MSG:READ,0-0-42,s=255,c=3,t=8,pt=1,l=1,sg=0:0
684 TSF:MSG:FPAR OK,ID=0,D=1
2081 TSM:FPAR:OK
2082 TSM:ID
2083 TSM:ID:OK
2085 TSM:UPL
2088 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=24,pt=1,l=1,sg=0,ft=0,st=OK:1
2095 TSF:MSG:READ,0-0-42,s=255,c=3,t=25,pt=1,l=1,sg=0:1
2100 TSF:MSG:PONG RECV,HP=1
2103 TSM:UPL:OK
2104 TSM:READY:ID=42,PAR=0,DIS=1
2109 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=OK:0100
2115 TSF:MSG:READ,0-0-42,s=255,c=3,t=15,pt=6,l=2,sg=0:0100
2123 TSF:MSG:SEND,42-42-0-0,s=255,c=0,t=17,pt=0,l=5,sg=0,ft=0,st=OK:2.3.1
2131 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=6,pt=1,l=1,sg=0,ft=0,st=OK:0
4141 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=11,pt=0,l=16,sg=0,ft=0,st=OK:AIQ Sensor MQ135
4150 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=12,pt=0,l=3,sg=0,ft=0,st=OK:1.0
4158 TSF:MSG:SEND,42-42-0-0,s=0,c=0,t=22,pt=0,l=0,sg=0,ft=0,st=OK:
4164 MCO:REG:REQ
4168 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=26,pt=1,l=1,sg=0,ft=0,st=OK:2
4174 TSF:MSG:READ,0-0-42,s=255,c=3,t=27,pt=1,l=1,sg=0:1
4179 MCO:PIM:NODE REG=1
4182 MCO:BGN:STP
4184 MCO:BGN:INIT OK,TSP=1
0
Val / Ro / value:19523 / 30443.00 / 0.004188 MCO:SLP:MS=30000,SMS=0,I1=255,M1=255,I2=255,M2=255
4195 TSF:TDI:TSL
4197 MCO:SLP:WUP=-1
4199 TSF:TRI:TSB
0
Val / Ro / value:22654 / 35325.00 / 0.004206 MCO:SLP:MS=30000,SMS=0,I1=255,M1=255,I2=255,M2=255
4213 TSF:TDI:TSL
4215 MCO:SLP:WUP=-1
4217 TSF:TRI:TSB
0
Val / Ro / value:29383 / 45818.00 / 1217.494228 TSF:MSG:SEND,42-42-0-0,s=0,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=OK:1617
4234 MCO:SLP:MS=30000,SMS=0,I1=255,M1=255,I2=255,M2=255
4239 TSF:TDI:TSL
4241 MCO:SLP:WUP=-1
4243 TSF:TRI:TSB
0
Val / Ro / value:27682 / 43165.00 / 1436.084253 TSF:MSG:SEND,42-42-0-0,s=0,c=1,t=37,pt=2,l=2,sg=0,ft=0,st=OK:1836
4259 MCO:SLP:MS=30000,SMS=0,I1=255,M1=255,I2=255,M2=255
4264 TSF:TDI:TSL```

Not sure it will help

Have tested the wiring with another sketch and it is good, it returns me values

/*
  Programme de test du MQ135 permettant de mesurer la présence de polluants dans l'atmosphère (CO, CO2 Alcool, fumées...)
  Pour plus d'infos ici https://www.projetsdiy.fr/mq135-mesure-qualite-air-polluant-arduino
  Utilise la librairie mq135.cpp mise à disposition par Georg Krocker https://github.com/GeorgK/MQ135
  Projets DIY - Mars 2016 - www.projetsdiy.fr
*/

#include "MQ135.h"
const int mq135Pin = 0;     // Pin sur lequel est branché de MQ135

MQ135 gasSensor = MQ135(mq135Pin);  // Initialise l'objet MQ135 sur le Pin spécifié

void setup()
{
    Serial.begin(9600);     // Initialise le port série à 9600 bps 
    //float rzero = gasSensor.getRZero();
    //Serial.print("R0: ");
    //Serial.println(rzero);  // Valeur à reporter ligne 27 du fichier mq135.h après 48h de préchauffage
    
}

void loop()
{
    float ppm = gasSensor.getPPM();
    float rzero = gasSensor.getRZero();
    Serial.print("R0: ");
    Serial.print(rzero);
    Serial.print(" A0: ");
    Serial.print(analogRead(mq135Pin));
    Serial.print(" ppm CO2: ");
    Serial.println(ppm);
    delay(1000);        // Actualise la mesure chaque seconde```

Thanks, looks promising

my serial monitor gives now

16 MCO:BGN:INIT NODE,CP=RNNNA---,REL=255,VER=2.3.1
26 TSM:INIT
27 TSF:WUR:MS=0
33 TSM:INIT:TSP OK
35 TSM:INIT:STATID=42
37 TSF:SID:OK,ID=42
39 TSM:FPAR
75 TSF:MSG:SEND,42-42-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
91 TSF:MSG:READ,0-0-42,s=255,c=3,t=8,pt=1,l=1,sg=0:0
96 TSF:MSG:FPAR OK,ID=0,D=1
2083 TSM:FPAR:OK
2084 TSM:ID
2085 TSM:ID:OK
2087 TSM:UPL
2093 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=24,pt=1,l=1,sg=0,ft=0,st=OK:1
2099 TSF:MSG:READ,0-0-42,s=255,c=3,t=25,pt=1,l=1,sg=0:1
2104 TSF:MSG:PONG RECV,HP=1
2107 TSM:UPL:OK
2108 TSM:READY:ID=42,PAR=0,DIS=1
2113 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=15,pt=6,l=2,sg=0,ft=0,st=OK:0100
2122 TSF:MSG:READ,0-0-42,s=255,c=3,t=15,pt=6,l=2,sg=0:0100
2129 TSF:MSG:SEND,42-42-0-0,s=255,c=0,t=17,pt=0,l=5,sg=0,ft=0,st=OK:2.3.1
2139 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=6,pt=1,l=1,sg=0,ft=0,st=OK:0
4150 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=11,pt=0,l=18,sg=0,ft=0,st=OK:Air Quality Sensor
4159 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=12,pt=0,l=3,sg=0,ft=0,st=OK:1.0
4167 TSF:MSG:SEND,42-42-0-0,s=0,c=0,t=22,pt=0,l=0,sg=0,ft=0,st=OK:
4173 MCO:REG:REQ
4177 TSF:MSG:SEND,42-42-0-0,s=255,c=3,t=26,pt=1,l=1,sg=0,ft=0,st=OK:2
4184 TSF:MSG:READ,0-0-42,s=255,c=3,t=27,pt=1,l=1,sg=0:1
4189 MCO:PIM:NODE REG=1
4191 MCO:BGN:STP
29201 MCO:BGN:INIT OK,TSP=1
0
LPG:0ppm    CO:0ppm    SMOKE:0ppm
30211 MCO:SLP:MS=30000,SMS=0,I1=255,M1=255,I2=255,M2=255
30216 TSF:TDI:TSL
30218 MCO:SLP:WUP=-1
30220 TSF:TRI:TSB
0
LPG:0ppm    CO:0ppm    SMOKE:0ppm
31232 MCO:SLP:MS=30000,SMS=0,I1=255,M1=255,I2=255,M2=255
31238 TSF:TDI:TSL````

So values are always 0 so something is wrong with the sensor.
And I can't find it in Domoticz also.

Not so easy :(

Hello,
I finally decided to give a try to my sensors but with no luck yet.
I have configured my sensors gateway as a MGTT on a RPI 3 on with I am running Domoticz

I wanted to test a first sensor based on the MQ135 gaz sensor.
I have uploaded on my Arduino nano the sketch AirQualitySensor.ino

But it looks that the Arduino is booting every few seconds.

Whats wrong ?

The serial monitor logs :

16 MCO:BGN:INIT NODE,CP=RNNNA---,REL=255,VER=2.3.1
26 TSM:INIT
27 TSF:WUR:MS=0
33 TSM:INIT:TSP OK
35 TSM:FPAR
37 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
429 TSF:MSG:READ,0-0-255,s=255,c=3,t=8,pt=1,l=1,sg=0:0
434 TSF:MSG:FPAR OK,ID=0,D=1
2046 TSM:FPAR:OK
2048 TSM:ID
2049 TSM:ID:REQ
2052 TSF:MSG:SEND,255-255-0-0,s=1,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
4059 TSM:ID
4060 TSM:ID:REQ
4062 TSF:MSG:SEND,255-255-0-0,s=220,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
6070 TSM:ID
6071 TSM:ID:REQ
6073 TSF:MSG:SEND,255-255-0-0,s=183,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
8081 TSM:ID
8082 TSM:ID:REQ
8084 TSF:MSG:SEND,255-255-0-0,s=146,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
10092 !TSM:ID:FAIL
10093 TSM:FAIL:CNT=1
10095 TSM:FAIL:DIS
10097 TSF:TDI:TSL
20100 TSM:FAIL:RE-INIT
20102 TSM:INIT
20108 TSM:INIT:TSP OK
20110 TSM:FPAR
20113 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
22120 !TSM:FPAR:NO REPLY
22122 TSM:FPAR
22124 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
23088 TSF:MSG:READ,0-0-255,s=255,c=3,t=8,pt=1,l=1,sg=0:0
23093 TSF:MSG:FPAR OK,ID=0,D=1
24132 TSM:FPAR:OK
24133 TSM:ID
24135 TSM:ID:REQ
24137 TSF:MSG:SEND,255-255-0-0,s=71,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
26145 TSM:ID
26146 TSM:ID:REQ
26149 TSF:MSG:SEND,255-255-0-0,s=34,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
28157 TSM:ID
28158 TSM:ID:REQ
28162 TSF:MSG:SEND,255-255-0-0,s=254,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
30169 TSM:ID
30170 TSM:ID:REQ
30173 TSF:MSG:SEND,255-255-0-0,s=218,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
32180 !TSM:ID:FAIL
32181 TSM:FAIL:CNT=2
32183 TSM:FAIL:DIS
32185 TSF:TDI:TSL
42188 TSM:FAIL:RE-INIT
42190 TSM:INIT
42196 TSM:INIT:TSP OK
42199 TSM:FPAR
42202 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
44209 !TSM:FPAR:NO REPLY
44211 TSM:FPAR
44213 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
46221 !TSM:FPAR:NO REPLY
46223 TSM:FPAR
46225 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
46716 TSF:MSG:READ,0-0-255,s=255,c=3,t=8,pt=1,l=1,sg=0:0
46722 TSF:MSG:FPAR OK,ID=0,D=1
48233 TSM:FPAR:OK
48234 TSM:ID
48235 TSM:ID:REQ
48238 TSF:MSG:SEND,255-255-0-0,s=107,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
50246 TSM:ID
50247 TSM:ID:REQ
50250 TSF:MSG:SEND,255-255-0-0,s=71,c=3,t=3,pt=0,l=0,sg=0,ft=0,st=OK:
52257 TSM:ID```