Thanks
I will try

@mfalkvidd
actually the sketch calls sense () from the inside of receive ()

void receive(const MyMessage &message) {
  
  if (message.isAck()) {
    ack = true;   //Serial.println("This is an ack from gateway");
  }

  else  {
    if (message.type == V_VAR1 && message.sensor == child_id_watchdog) {           // watchdog 
      watchdog = message.getLong();                                                // recoit nouvelle valeur watchdog de jeedom toutes les minutes
      dateDernierChangement = millis();
      jeton=!jeton;
      send_state(10,jeton);
    }
    if (message.type == V_STATUS && message.sensor == child_id_salle_manger) {          
      etat_salle_manger = message.getBool();  
      time_out_salle_manger = millis();
    }
    if (message.type == V_STATUS && message.sensor == child_id_sejour) {     

I didn't know you shouldn't do it
I moved it to void loop () and everything works perfectly

void receive(const MyMessage &message) {
  
  if (message.isAck()) {
    ack = true;   //Serial.println("This is an ack from gateway");
  }

  else  {
    if (message.type == V_VAR1 && message.sensor == child_id_watchdog) {           // watchdog 
      watchdog = message.getLong();                                                // recoit nouvelle valeur watchdog de jeedom toutes les minutes
      dateDernierChangement = millis();
      watchdog_recu=true;                // sert pour envoyer jeton a jeedom
    }

in the void loop()

if (watchdog_recu == true)  {
    watchdog_recu = false;
    jeton=!jeton;
    send_state(10,jeton);   // envoi jeton à jeedom pour indiquer que la comm est ok
  }

thanks again for your help so fast

I wish you a happy new year from Aix en Provence (France)
Jean-luc