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Original Post

I'm a member of the ThingSpeak team. I'd like to learn more about how the ThingSpeak community accesses channel data. Your feedback can help us make ThingSpeak better!

(A) Which of these statements best describes when the data you are interested in typically occurs?

1. the last X hours / minutes / seconds
2. a specific time window, e.g. "Monday, October 4th, 2021 9:00AM to 10:00PM"
3. the last N feeds
4. all data in the channel

(B) What is a typical duration of time that you are interested in? (e.g. "3 hours", "a few minutes")

(C) How many data points do you typically expect to read?

Hello everyone! i want to send current sensor data using Arduino and nodeMCU to thingspeak. is there anyone who worked on something before. your responses will be highly appreciatable. thanks in advance

Hello,

I am sending mqtt values from esp8266 devices to different channels - e.g. https://thingspeak.com/channels/1182897

The values are sent correctly and also show up on the channel's page correctly and quickly in time.

But mqtt receivers are getting the data with a varying long delay. Often the delay is 1h, so I first thought, this could be a time zone problem. But that's not the case.

I tried two different mqtt clients: Both get the values at the same (late time): E.g. when I now get a value from channels/1182897/subscribe/fields/field3 and look into the history of values (using "Data Import/Export") then this value can be found 20 minutes up to 1 hour ago. This can also be confirmed when looking into the device's logs.

What could I do to be up-to-date with my values? Thank you very much. Dirk

I have a chart of data and need to eliminate the outliers which are making the chart look bad. Is there a configuration for this?

Hello, I try to publish to an already working channel. I have created an device and using the credentials shown in the image. I would like connect via TCP and port 1883 to mqtt3.thingspeak.com My Library always returns "Connection Refused - Bad Username or Password". This means it already has got a CONNACK reply. I have already successfully published an item to another server. So, the Lib basically works and I am using it correctly. I do not have mistyped the credentials. Could there be something on the Thingspeak side? Could you please help me with that? Thank you in advance.

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I currently have my ThingSpeak log temp, airflow velocity raw and airflow velocity filtered. The column names show as field1, field 2 and field 3. Is there a way for me to change field1 to temperature? Thanks

Hi,

I am experiencing trouble in sending the actual sensor values to Thingspeak. I use a code template that I downloaded from a github repository https://github.com/mathworks/thingspeak-arduino/tree/master/examples/ESP32/WriteMultipleFields. The main issue is that I don't know how to fill out the source code to get real sensor values instead of random values.

I am using a DHT sensor, from which I want to measure both the temperature and the humidity. Here is what it looks like in the serial monitor after uploading the code to the ESP32 dev board.

Here is my code that I amended from the source template, and uploaded to the ESP32 board.

#include "DHT.h"
#include <WiFi.h>
#include "ThingSpeak.h"

// The wire is in pin 14 as required by the DHT-sensor, so it is written here:
#define DHTPIN 14    

// We use a DHT11-sensor
#define DHTTYPE DHT110

const char* ssid = "Koti_9BE9";   // your network SSID (name) 
const char* password = "XXXXXXX";   // your network password

WiFiClient  client;

// We write one (1) as the channel number. Assumably in that order in which they are in the MyChannels-page. 
unsigned long myChannelNumber = 1;
const char * myWriteAPIKey = "NW34MMOB5J1NGRL2";

// Timer variables
unsigned long lastTime = 0;
unsigned long timerDelay = 10000; // This specifies what kind of delay we want between measurements. DHT11
// The fastest measurement interval of DHT sensors is 2000 ms (2 seconds).

// An object from where values are brought from the DHT library
DHT dht(DHTPIN, DHTTYPE);

// Initialize our values. Writing down the values that need to be measured from DHT-sensors: 
// humidity h, temperature t, and temperature in fahrenheit-scale f
float h = dht.readHumidity();
float t = dht.readTemperature();
float f = dht.readTemperature(true);
String myStatus = "";

void setup() {
  Serial.begin(115200);
  Serial.println(F("DHT11 test!"));

    dht.begin();

    WiFi.mode(WIFI_STA);   

   ThingSpeak.begin(client);
  }

void loop() {

    delay(20000);

    float h = dht.readHumidity();

    float t = dht.readTemperature();

    float f = dht.readTemperature(true);

    if (isnan(h) || isnan(t) || isnan(f)) {
      Serial.println(F("Failed to read from DHT sensor!"));
      return;
    }

    if(WiFi.status() != WL_CONNECTED){      
      Serial.print("Attempting to connect");
      while(WiFi.status() != WL_CONNECTED){
        WiFi.begin(ssid, password); 
        delay(5000);     
      } 
      Serial.println("\nConnected.");
    }

    float hif = dht.computeHeatIndex(f, h);

    float hic = dht.computeHeatIndex(t, h, false);

    Serial.print(F("Humidity: "));
    Serial.print(h);
    Serial.print(F("%  Temperature: "));
    Serial.print(t);
    Serial.print(F("°C "));
    Serial.print(f);
    Serial.print(F("°F  Heat index: "));
    Serial.print(hic);
    Serial.print(F("°C "));
    Serial.print(hif);
    Serial.println(F("°F"));

int x = ThingSpeak.writeFields(myChannelNumber, myWriteAPIKey);

if(x == 200){
  Serial.println("Channel update successful.");
}
else{
  Serial.println("Problem updating channel. HTTP error code " + String(x));
}
}

Many thanks for any advice.

Lauri

i have url that contains value for reading data, how can i send data to field from url that i have?

I have a project that collects data from a CO2 sensor and stored it in these ints:

    CO2PPM = (int)data[2] * 256 + (int)data[3];
    temperature = (int)data[4] - 40;  

which are defined as ints. Then just before the http request, they are processed like this:

       static char outstr3[15];
       static char outstr4[15];
       String dataString3 = dtostrf(CO2PPM, 8, 2, outstr3);
       String dataString4 = dtostrf(temperature, 8, 2, outstr4);

and finally used in the GET request:

          wifly.println("GET /update?api_key=apikey&field1="dataString4"&field2="+dataString3+" HTTP/1.1");

which fails to successfully register the data into TS. However if I hardcode it like this:

          wifly.println("GET /update?api_key=apikey&field1=23.45&field2=67.89 HTTP/1.1");

it works, the data is registered.

Any idea how to fix this issue?

Greetings!

So, I'm working on a project that needs to send collected data using a SIM808 over GPRS to ThingSpeak to multiple fields. The upload interval is 2 minutes with samples taken every 10 seconds and each batch of samples includes 19 bytes of data (12 sets of 19 bytes equal 228B for each bulk data pack that has to be sent and the memory can be flushed). It's worth mentioning that I'm using an Arduino Pro Mini (ATmega328P).

I've looked at the bulk data upload example, and I'm having some trouble adapting it to the SIM808. I am also not sure how to send multiple fields using the bulk method. Unfortunately, I don't have much time to tinker with the code as the whole project had to be done in 2 days and I've only got one day to finish. I'd appreciate any help regarding this as I'm on a very tight schedule.

Thanks in advance!

We've started a new video series on how and why to use ThingSpeak. IoT from Data to Action . Most of you pros here at the forum probably already know this stuff, but there's some great overview material in these videos if you are interested. Two of four planned movies are posted, Ill let you know again when the others come out too. -Christopher

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Hello! I have been working on an app for viewing thingspeak numerical data as graphs and I'm planning to publish it on playstore soon. If anybody is interested to test the beta version I would appreciate it. Here is the link https://play.google.com/apps/testing/com.mlundell.theThingV

ThankYou !

Magnus

I have both of my account profile and channel export time zones set to "(GMT+8000)Beijing". The datetime from the exported feeds.csv looks like:

'2021-09-06 11:16:28 CST'

I want to import data, but MATLAB do not directly understand its datetime format. I assume "CST" to be "China Standard Time", but when I try to convert it to datetime, MATLAB throws an error:

 >> datetime(s,'InputFormat',"yyyy-MM-dd HH:mm:ss z","TimeZone","Asia/Shanghai","Locale","zh_CN")
 Error using datetime (line 651)
 Unable to convert '2021-09-06 11:16:28 JST' to datetime using the format 'yyyy-MM-dd HH:mm:ss z' and locale 'zh_CN'.

However if I change the "Locale" to US instead:

>>datetime(s,'InputFormat',"yyyy-MM-dd HH:mm:ss z","TimeZone","Asia/Shanghai","Locale","en_US")
ans = 
    datetime
07-Sep-2021 01:16:28

There is no error, but the time is wrong and is 14 hours ahead. So I guess that MATLAB sees this "CST" as "Central Standard Time".

My point is:

1. It's pretty strange that the datetime exported by ThingSpeak could not be directly understood by MATLAB. MATLAB is supposed to work with ThingSpeak data seamlessly, but now I have to find a detour to import ThingSpeak data to MATLAB.
2. It seems that the datetime function needs improvement to understand this "CST" timezone, or that ThingSpeak could improve its datetime output format.

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