MQTT with Sim 7000C NB-IoT Network

[najabhaider96]

I'm trying to use MQTT on Sim 7000C with NB-IoT Network I'm using this example code for trying to use MQTT with NB-IoT Network configured but not connected with broker. Modem: SIM7000C R1351

// Select your modem: //#define TINY_GSM_MODEM_SIM800 // #define TINY_GSM_MODEM_SIM900 // #define TINY_GSM_MODEM_SIM808 // #define TINY_GSM_MODEM_SIM868

define TINY_GSM_MODEM_SIM7000

// #define TINY_GSM_MODEM_UBLOX // #define TINY_GSM_MODEM_M95 // #define TINY_GSM_MODEM_BG96 // #define TINY_GSM_MODEM_A6 // #define TINY_GSM_MODEM_A7 // #define TINY_GSM_MODEM_M590 // #define TINY_GSM_MODEM_MC60 // #define TINY_GSM_MODEM_MC60E // #define TINY_GSM_MODEM_ESP8266 // #define TINY_GSM_MODEM_XBEE

include

include

// Set serial for debug console (to the Serial Monitor, default speed 115200)

define SerialMon Serial

include

SoftwareSerial SerialAT(5, 4); // RX, TX

// Your GPRS credentials // Leave empty, if missing user or pass const char apn[] = "apn"; const char user[] = ""; const char pass[] = "";

// MQTT details const char* broker = "m21.cloudmqtt.com";

const char topicLed = "GsmClientTest/led"; const char topicInit = "GsmClientTest/init"; const char* topicLedStatus = "GsmClientTest/ledStatus";

TinyGsm modem(SerialAT); TinyGsmClient gsmClient(modem); PubSubClient mqtt(gsmClient);

define LED_PIN 13

int ledStatus = LOW;

long lastReconnectAttempt = 0;

void setup() { pinMode(LED_PIN, OUTPUT);

// Set console baud rate SerialMon.begin(9600); delay(10);

// Set GSM module baud rate SerialAT.begin(9600); delay(3000);

// Restart takes quite some time // To skip it, call init() instead of restart() SerialMon.println("\n\n\nInitializing modem..."); modem.restart();

String modemInfo = modem.getModemInfo(); SerialMon.print("Modem: "); SerialMon.println(modemInfo);

// Unlock your SIM card with a PIN //modem.simUnlock("1234");

Serial.print("Sim Operator : "); Serial.println(modem.getOperator()); Serial.print("Signal Strength : "); Serial.println(modem.getSignalQuality());

SerialMon.print("Waiting for network..."); if (!modem.waitForNetwork()) { SerialMon.println(" fail"); while (true); } SerialMon.println(" OK");

SerialMon.print("Connecting to "); SerialMon.print(apn); if (!modem.gprsConnect(apn, user, pass)) { SerialMon.println(" fail"); while (true); } SerialMon.println(" OK");

Serial.print("Local IP : "); Serial.println(modem.localIP());

// MQTT Broker setup mqtt.setServer(broker, 19279); mqtt.setCallback(mqttCallback); }

boolean mqttConnect() { SerialMon.print("Connecting to "); SerialMon.print(broker);

// Connect to MQTT Broker // boolean status = mqtt.connect("GsmClientTest");

// Or, if you want to authenticate MQTT: boolean status = mqtt.connect("GsmClientName", "user", "password");

if (status == false) { SerialMon.println(" fail"); return false; } SerialMon.println(" success"); mqtt.publish(topicInit, "GsmClientTest started"); mqtt.subscribe(topicLed); return mqtt.connected(); }

void loop() {

if (!mqtt.connected()) { SerialMon.println("=== MQTT NOT CONNECTED ==="); // Reconnect every 10 seconds unsigned long t = millis(); if (t - lastReconnectAttempt > 10000L) { lastReconnectAttempt = t; if (mqttConnect()) { lastReconnectAttempt = 0; } } delay(100); return; }

mqtt.loop(); }

void mqttCallback(char topic, byte payload, unsigned int len) { SerialMon.print("Message arrived ["); SerialMon.print(topic); SerialMon.print("]: "); SerialMon.write(payload, len); SerialMon.println();

// Only proceed if incoming message's topic matches if (String(topic) == topicLed) { ledStatus = !ledStatus; digitalWrite(LED_PIN, ledStatus); mqtt.publish(topicLedStatus, ledStatus ? "1" : "0"); } }

OUTPUT

Waiting for network... OK Connecting to apnname OK Local IP : .45..144 === MQTT NOT CONNECTED === Connecting to m21.cloudmqtt.com fail === MQTT NOT CONNECTED === Connecting to m21.cloudmqtt.com fail === MQTT NOT CONNECTED ===

[SRGDamia1]

I assume you have the real port/username/password in your code.

What's the status code that pubsubclient is giving you? (Add a Serial.print(status); right after boolean status = mqtt.connect("GsmClientName", "user", "password");) Look in the docs for the pubsubclient library to check the meaning of the status code. (https://pubsubclient.knolleary.net/api#state) That should help you track down the issue.

Can you connect to other sites using the same module? Do other examples (like the webclient example) work?

Otherwise, try posting your AT log. There's not too much I can see without that.

[SRGDamia1]

Depending on your SIM provider, you may have to set your preferred network band and mode:

setNetworkMode(uint8_t mode);
// 2 - Automatic
// 13 - GSMonly
// 38 - LTEonly
// 51 - GSMandLTEonly

setPreferredMode(uint8_t mode);
// 1 - CAT-M
// 2 - NB-Iot
// 3 - CAT-M and NB-IoT

[Mark-Wills]

I notice you are trying to connect to m21.cloudmqtt.com. Are you sure you have access to the internet from your provider? Many NBIoT providers operate their networks in an APN/VPN which does not have access to the big, bad internet, unless a gateway is specifically installed. Try opening a http port 80 connection to google.com or something like that. If it works... then you have access to the internet. If not, you're operating in a closed APN (probably company provided SIM card where all the SIM cards are in the same network so they can talk to each other, but there is no external gateway. This is how the SIM cards that we use work by design - our MQTT box is within our APN IP address range).

Regards

Mark