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Dear all,
in the Matlab Analysis I use twice the fuinction thingSpeakRead to read data from a channel, from two different fields.
The problem is that so far, only one of the values is read properly and the other one delivers NaN.
What could be the reason?
Thank you!
Here's my code:
% TODO - Replace the [] with channel ID to read data from:
readChannelID = [xxx];
% TODO - Enter the Read API Key between the '' below:
readAPIKey = 'xxxxxxxx';
% TODO - Replace the [] with channel ID to write data to:
writeChannelID = [xxx];
% TODO - Enter the Write API Key between the '' below:
writeAPIKey = 'xxxxxx';
%% Read Data %%
%data = thingSpeakRead(readChannelID, 'ReadKey', readAPIKey);
temperature = thingSpeakRead(xxx,Fields=[1])
humidity = thingSpeakRead(xxx,Fields=[8])
Hello I want to upload a single value from a raspberry and I can't find a way. Can somebody help me?
Lot of Thanks¡¡
TimeControl Ran, but it didn't appiied it to channel (chart has not been updated in the right time and in the end, it did not ran, had to manually run the script by myself). And I would like to request to MathWorks to fix (modify) my chart to right time and value and investigate this problem.


I want to control the level my water tank with a esp8266 and Thingspeak.
I can see the level in Thingspeak. This is working.
Now I want to send 2 emails :
- One daily email with the actual level
- Alarm email when level is below a setpoint.
How can I incorporate the value from a channel in the email ?
What I have now for the daily email , but with errors :
alert_body = 'huidig peil regenput';
channelID = ..........;
% Provide the ThingSpeak alerts API key. All alerts API keys start with TAK.
alertApiKey = 'TAK...............';
% Set the address for the HTTTP call
alertUrl="https://api.thingspeak.com/alerts/send";
% webwrite uses weboptions to add required headers. Alerts needs a ThingSpeak-Alerts-API-Key header.
options = weboptions("HeaderFields", ["ThingSpeak-Alerts-API-Key", alertApiKey ]);
% Set the email subject.
alertSubject = sprintf("Niveau regenput " );
% Read the recent data.
peil = thingSpeakRead(channelID,'Fields',1);
% Check to make sure the data was read correctly from the channel.
% Set the outgoing message
webwrite(alertUrl , "body", alertBody, "subject", alertSubject,'Fields',peil);
% Catch errors so the MATLAB code does not disable a TimeControl if it fails
try
webwrite(alertUrl , "body", alert_body, "subject", alertSubject, options);
catch someException
fprintf("Failed to send alert: %s\n", someException.message);
end
The errors I receive :
Unrecognized function or variable 'alert_Body'.
Error in Read Channel to Trigger Email 1 (line 24)
webwrite(alertUrl , "body", alert_Body, "subject", alertSubject,"Fields",peil);
Manny thanks in advance
Hallo,
ich Neuling hier, und habe das Beispiel WriteMultipleFields benutzt um die Funktionsweise zu verstehen.
So weit so gut, hat auch alles grklappt. Jetzt nach 2 Tagen bekomme ich immer eine Fehlermeldung.
Problem updating channel. HTTP error code -401 abwechselnd mit
Channel update successful.
Es ist immernoch die gleiche Software, Board ist WiFi LoRa 32 V3.
Buongiorno, non mi è possibile connetermi al canale di thingspeak che ho creato, per passare i dati tramite MQTT. Il codice segue la libreria PubSubClient su arduino ide, l'errore restituito dal serial monitor dell'ide é: -4 : MQTT_CONNECTION_TIMEOUT - the server didn't respond within the keepalive time.
Allego il codice per eventuali verifiche:
Grazie per a disponibilità
#include "PubSubClient.h"
#include <ESP8266WiFi.h>
#include "secrets.h"
bool DEBUG = false; // true=serial message of debug enabled
char* server = "mqtt.thingspeak.com";
WiFiClient wifiClient;
PubSubClient client(server, 1883, wifiClient);
String payload;
// BME280 Setting
#include <Wire.h>
#include <Adafruit_BME280.h>
//#define SEALEVELPRESSURE_HPA (1013.25)
Adafruit_BME280 bme; // I2C
bool BMEStatus;
ADC_MODE(ADC_VCC); // Set ADC for read Vcc
// Update time in seconds. Min with Thingspeak is ~20 seconds
const int UPDATE_INTERVAL_SECONDS = 3600; //il clock interno ha un errore del 5% questo valore va tarato sperimentalmente
//const int UPDATE_INTERVAL_SECONDS = 60; // caricamento ogni minuto solo per test
void setup()
{
// Connect BME280 GND TO pin14 OR board's GND
pinMode(14, OUTPUT);
digitalWrite(14, LOW);
Serial.begin(115200);
delay(10);
// BME280 Initialise I2C communication as MASTER
Wire.begin(13, 12); //Wire.begin([SDA], [SCL])
BMEStatus = bme.begin();
if (!BMEStatus)
{
if (DEBUG) { Serial.println("Could not find BME280!"); }
//while (1);
}
// Weather monitoring See chapter 3.5 Recommended modes of operation
bme.setSampling(Adafruit_BME280::MODE_FORCED,
Adafruit_BME280::SAMPLING_X1, // temperature
Adafruit_BME280::SAMPLING_X1, // pressure
Adafruit_BME280::SAMPLING_X1, // humidity
Adafruit_BME280::FILTER_OFF );
// read values from the sensor
float temperature, humidity, pressure;
if (BMEStatus)
{
temperature = bme.readTemperature();
humidity = bme.readHumidity();
pressure = bme.readPressure() / 100.0F;
}
else
{
if (DEBUG) Serial.println("Could not find BME280!");
temperature=0;
humidity=0;
pressure=0;
}
float voltage = ESP.getVcc();
voltage = voltage/1024.0; //volt
if (DEBUG)
{
Serial.println("T= " + String(temperature) + "°C H= " + String(humidity) + "% P=" + String(pressure) + "hPa V=" + voltage + "V");
}
// Construct MQTT payload
payload="field1=";
payload+=temperature;
payload+="&field2=";
payload+=humidity;
payload+="&field3=";
payload+=pressure;
payload+="&field4=";
payload+=voltage;
payload+="&status=MQTTPUBLISH";
//Connect to Wifi
if (DEBUG)
{
Serial.println();
Serial.print("\nConnecting to WiFi SSID ");
Serial.print(SECRET_SSID);
}
WiFi.begin(SECRET_SSID, SECRET_PASS);
int timeOut=10; // Time out to connect is 10 seconds
while ((WiFi.status() != WL_CONNECTED) && timeOut>0)
{
delay(1000);
if (DEBUG) { Serial.print("."); }
timeOut--;
}
if (timeOut==0) //No WiFi!
{
if (DEBUG) Serial.println("\nTimeOut Connection, go to sleep!\n\n");
ESP.deepSleep(1E6 * UPDATE_INTERVAL_SECONDS);
}
if (DEBUG) // Yes WiFi
{
Serial.print("\nWiFi connected with IP address: ");
Serial.println(WiFi.localIP());
}
// Reconnect if MQTT client is not connected.
if (!client.connected())
{
reconnect();
}
mqttpublish();
delay(200); // Waiting for transmission to complete!!! (ci vuole)
WiFi.disconnect( true );
delay( 1 );
if (DEBUG) { Serial.println("Go to sleep!\n\n"); }
// Sleep ESP and disable wifi at wakeup
ESP.deepSleep( 1E6 * UPDATE_INTERVAL_SECONDS, WAKE_RF_DISABLED );
}
void loop()
{
//there's nothing to do
}
void mqttpublish()
{
// read values from the sensor
float temperature, humidity, pressure;
if (DEBUG)
{
Serial.print("Sending payload: ");
Serial.println(payload);
}
// Create a topic string and publish data to ThingSpeak channel feed.
String topicString ="channels/" + String( channelID ) + "/publish/"+String(writeAPIKey);
unsigned int length=topicString.length();
char topicBuffer[length];
topicString.toCharArray(topicBuffer,length+1);
if (client.publish(topicBuffer, (char*) payload.c_str()))
{
if (DEBUG) Serial.println("Publish ok");
}
else
{
if (DEBUG) Serial.println("Publish failed");
}
}
void reconnect()
{
String clientName="MY-ESP";
// Loop until we're reconnected
while (!client.connected())
{
if (DEBUG) Serial.println("Attempting MQTT connection...");
// Try to connect to the MQTT broker
if (client.connect((char*) clientName.c_str()))
{
if (DEBUG) Serial.println("Connected");
}
else
{
if (DEBUG)
{
Serial.print("failed, try again");
// Print to know why the connection failed.
// See http://pubsubclient.knolleary.net/api.html#state for the failure code explanation.
Serial.print(client.state());
Serial.println(" try again in 2 seconds");
}
delay(2000);
}
}
}
I have been having problems sending ThingSpeak alerts so I created a simple routine that demonstrates the problem. The code executes successfully but I never receive an email with the alert. What am I doing wrong?
% Set Thingspeak address, alerts API key, and options for the HTTTP call
alertUrl = "https://api.thingspeak.com/alerts/send";
alertApiKey = "TAKxxxxxxxxxxxxxxxx";
options = weboptions("HeaderFields",["ThingSpeak-Alerts-API-Key",alertApiKey]);
% Set content for email subject and body.
alertSubject = "ThingSpeak Alert Subject";
alertBody = "ThingSpeak Alert Body";
% Catch errors so the MATLAB code does not disable a TimeControl if it fails
try
webwrite(alertUrl, "body", alertBody, "subject", alertSubject, options);
catch Exception
fprintf("Failed to send alert: %s\n", Exception.message);
end
We are thrilled to announce the grand prize winners of our MATLAB Flipbook contest! This year, we invited the MATLAB Graphics Infrastructure team, renowned for their expertise in exporting and animation workflows, to be our judges. After careful consideration, they have selected the top three winners:
Judge comments: Creative and realistic rendering with well-written code
2nd place - Christmas Tree / Zhaoxu Liu
Judge comments: Festive and advanced animation that is appropriate to the current holiday season.
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In addition, after validating the votes, we are pleased to announce the top 10 participants on the leaderboard:
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Congratulations to all! Your creativity and skills have inspired many of us to explore and learn new skills, and make this contest a big success!
Am running multiple sensors in the field producing strings of data then sending them to a node. The node is an Arduino Uno on which SIM 800 is attached for internet connectivity. After computation, the result is several strings that i want to display to things speak. The code i have so far can only upload numerical data. Am in need of help to display these strings in Thingsspeak.Help me.
Dear Team,
I have populated my data on ThingsBoard platform using ESP8266, now I want to read that data using MATLAB Industrial Communication Toolbox. I have written a code for this purpose below,
% Replace these values with your ThingsBoard MQTT broker details
brokerAddress = "ssl://demo.thingsboard.io"; % Adjust the broker address
port = 1883; % Use the appropriate port for secure MQTT
% Replace these values with your ThingsBoard device details
clientID = "";
userName = "";
password = ""; % Leave empty if not required
% Replace this with the path to the root certificate you downloaded
rootCert = "";
% Create an MQTT client
mqClient = mqttclient(brokerAddress, 'Port', port, 'ClientID', clientID, ...
'Username', userName, 'Password', password, 'CARootCertificate', rootCert);
% Check if the connection is established
mqClient.Connected
% Expected output: ans = int32(1)
% Subscribe to the telemetry topic
topicToSub = "v1/devices/me/telemetry";
subscribe(mqClient, topicToSub);
% Wait for a while to receive messages (adjust the time as needed)
pause(60);
% Peek at the MQTT client to view received messages
peek(mqClient);
% Close the MQTT client
clear mqClient;
%%%%__________________Output Result______________________%%%%%
>> MQTT_Receive
Warning: Using a port that allows unencrypted communication. For confidential matters, considering using an encryption
enforcing port, such as 8883.
Error using MQTT_Receive
Failed to establish a connection with broker "ssl://demo.thingsboard.io".
I desperately seeking your assistance in this regard
The MATLAB Flipbook Mini Hack contest has concluded! During the 4 weeks, over 600 creative animations have been created. We had a lot of fun and a great learning experience! Thank you, everyone!
Now it’s the time to announce week 4 winners. Note that grand prize winners will be announced shortly after we validate votes on winning entries.
Realism:
Holiday & Season:
Abstract:
Cartoon:
Congratulations, weekly winners!We will reach out to you shortly for your prizes.
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Participants of all skill levels from anywhere in the world are welcome to compete!
MathWorks provides the following resources for all participants:
I'm logging data which I'd like to see on a daily basis. ie each day the chart x axis resets to 12midnight to 12midnight for the current day and just shows todays data. Is this possible please ?
Have you marveled at the breathtaking, natural-looking animations crafted by the creative minds in the Flipbook Mini Hack contest? Think of @Tim, @Jenny Bosten, and @Zhaoxu Liu / slandarer- their work is nothing short of extraordinary.

So, what's their secret? Adam Danz, a developer in the MATLAB Graphics and Charting team and a top community contributor, has graciously unveiled the mysteries in his latest blog post - "Creating natural textures with power-law noise: clouds, terrains, and more." The post offers simple, step-by-step instructions and code snippets, empowering you to grasp these enchanting techniques effortlessly.
Check it out and we hope it sparks your creativity and serves as a wellspring of inspiration. With only 3 days remaining before the contest draws to a close, it's time to dive into the code and let your imagination soar!
In Week 3, we reached the 400-animations milestone! Let’s work together to achieve the 500-animations goal!
During the last week of the contest, we strongly encourage you to inspire your colleagues, classmates, or friends to vote. Voters will also have the opportunity to win a MATLAB T-shirt.
Mini Hack Winners - Week 3
Math, Physics, or Science explanation:
Most creative remix:
40:
Math is beautiful:
Mashup (Combined themes):
Nature:
Holidays:
Congratulations, winners!
In week 4, we’d love to see more entries in the following categories:
- Holidays:
- Seasons:
- Abstract:
- Mashup (mixed categories)
A gentle reminder that you have a direct impact on the next generation of animation tools in MATLAB! Don’t forget to share your thoughts and ideas with us.
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Vote on your favorite animations before Dec. 3rd. We will give out MATLAB T-shirts to 10 lucky voters!


Tips: the more you vote, the higher your chance to win.
i've finished writing the code for my ~masterpiece~ and it doesn't run on the contest new entry page. it runs on matlab on my desktop and in the matlab live editor in my browser, but not where i really need it to. usually it'll draw the first frame the first time i run the code in a new window, but not any subsequent times. whether i hit "run" or "create animation", the screen grays out as it's supposed to, but then returns to normal without generating the first frame or animation.
i'm not getting a timeout warning or any error messages. i timed the code on my laptop and it takes about 100ish seconds to run and generate the animation the first time i run it before clearing everything from my workspace (and then it takes about twice as long each subsequent time, which makes me a bit nervous. can't figure out why this is the case at all!), which is well within the 255 second limit for the contest. as far as i know, the most computationally expensive function i'm using is patch(). i'm pretty close to the character limit, but i don't know if that's part of the problem.
i tried vectorizing some of the code instead of using for loops, which made the code run slightly slower. i tried using a nested function instead of using drawframe() and an auxiliary function, but that didn't help. i tried clearing all variables except f at the end of drawframe() to no avail. i tried using the close command at the start of drawframe(), with similar success. i updated chrome, closed a bunch of windows, tried safari, used my sister's laptop, all with no luck.
has anyone else had this or a similar problem? any advice?
thanks!
Hello
I have been using ThingSpeak for about 2 years with no problems. I am observing sensor data and connecting widgets to some of the values. Since yesterday, there are some of the widgets that send blank values. Have you changed something?
Thank you
Just in two weeks, we already have 300 entries and 2,000 votes! We are so impressed by your creative styles, artistic talents, and ingenious programming techniques.
Now, it’s time to announce the weekly winners!
Mini Hack Winners - Week 2
Time & Space:
Trees:
Cartoon:
Symbolism:
Realism:
Fractal:
Multi-Entry Stories:
Explanatory:
Light:
MATtropolis:
Congratulations! Each of you won your choice of a T-shirt, a hat, or a coffee mug. We will contact you after the contest ends.
New categories for Week 3!
- 40: MathWorks will celebrate its 40th Anniversary in 2024. You will have opportunities to win special prizes!
- Most creative remix
Categories we’d love to see more entries in
- Multi-Entry Stories (e.g. Jr’s Matzilla series)
- MATropolis
- Math/Physics Explanation
Finally, just a reminder that you have a direct impact on the next generation of animation tools in MATLAB! Don’t forget to share your thoughts and ideas with us.