thingsboard-client-sdk: [Question] Server-Side RPC: Receiving Attributes doesn't work

• Generic
• Rule Engine(?)

Description Hey guys,

i’m currently working on a server-side rpc application. I basically want to turn on an analog LED via TB. The later works fine (see picture), but when I also want to mirror the analog led on my dashboard, like in this tutorial. Therefore I created a server-side attribute called ‘ledStatus’ and linked an led indicator to its changes. To send the status i use this TB-function for example:

client.sendAttributeBool("ledStatus", ledStatus);

The problem is that TB doesn’t seemt to receive the change of the ledStatus. Am I missing something? Do i maybe have to make a rule chain to process information coming from the device?

I hope my problem is kind of understandable. Suggestions are always appreciated 😃

Greetings Reno

Here is the current code. I use the Arduino IDE for coding:

#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <ThingsBoard.h>

// AP-DE
#define home "XXXXX"
#define homepw "XXXXXXXX"

// Auswahl des TB-Access Points:
#define TB_TOKEN "XXXXXX" 
#define TB_SERVER "demo.thingsboard.io"
//#define TB_PORT 1883

// Initialization:
WiFiClient wifiClient;           
ThingsBoard client(wifiClient);  

// Select AP:
const char* ssid = home;      
const char* password = homepw;

// Other Variables:
const int led = D2;
bool ledStatus = false;
bool previousState = false;

int status = WL_IDLE_STATUS;

void setup() {

  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(led, OUTPUT);
  digitalWrite(led, LOW);
  Serial.begin(9600);               
  InitWiFi();                             
  client.connect(TB_SERVER, demo_TOKEN);  // Definition des MQTT-Server
}

///////////////////// RPC-SETTINGS /////////////////////

RPC_Response processSwitchChange(const RPC_Data& data) {
  Serial.println("Received 'processSwitchChange'-method: ");
  char params[10];
  serializeJson(data, params);
  String _params = params;

  if (_params == "true") {
    Serial.println("SWITCH: ON");
    ledStatus = true;
    return RPC_Response("processSwitchChange", "true");

  } else if (_params == "false") {
    Serial.println("SWITCH: OFF");
    ledStatus = false;
    return RPC_Response("processSwitchChange", "false");
  }
}

const size_t callbacks_size = 1;
RPC_Callback callbacks[callbacks_size] = {
  { "processSwitchChange", processSwitchChange }
};

bool subscribed = false;  //RPC-Subscribe Status

///////////////////////////////////////// //Serial.printf(previousState != ledStatus ? "true" : "false");

void loop() {

  // Maintain connection
  if (!client.connected()) {
    reconnect();
  }

  checkRPC_Subscription();

  // Sends 
  if (previousState != ledStatus) {
    Serial.println();
    Serial.println("[SWITCH STATE CHANGED]");

    if (ledStatus == true) {
      digitalWrite(led, HIGH);
      Serial.println("LED: ON");
      client.sendAttributeBool("ledStatus", true);
    } else {
      digitalWrite(led, LOW);
      Serial.println("LED: OFF");
      client.sendAttributeBool("ledStatus", false);
    }

    previousState = ledStatus;
  }

  client.loop();
}

/////////////////////////////// OTHER FUNCTIONS ////////////////////////////////////

void InitWiFi() {
  Serial.print("Connecting to Access Point...");
  WiFi.begin(ssid, password);  // Eingabe der Zugangsdaten

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);  // "." bis Verbindung hergestellt ist
    Serial.print(".");
  }
  Serial.println();
  Serial.print("Connected! IP address: ");
  Serial.println(WiFi.localIP());
}

void reconnect() {
  while (!client.connected()) {

    status = WiFi.status();
    if (status != WL_CONNECTED) {
      InitWiFi();
    }

    // Reconnect
    Serial.print("Connecting to ThingsBoard Device ...");
    if (client.connect("ESP8266 Device", TB_TOKEN, NULL)) {
      Serial.println("[DONE]");
    } else {
      Serial.print("[FAILED] Retrying in 5 seconds]");
      delay(5000);
    }
  }
}


void checkRPC_Subscription() {
  if (!subscribed) {
    Serial.println("Subscribing for RPC...");

    if (!client.RPC_Subscribe(callbacks, callbacks_size)) {
      Serial.println("Failed to subscribe for RPC");
      return;
    }

    Serial.println("Subscribe done");
    subscribed = true;
  }
}

Environment

• OS: Win10,
• ThingsBoard: TB Demo
• Browser: Firefox