MATLAB Answers

ThingSpeak don't update channel automatic

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Sergio R
Sergio R on 6 May 2019
Answered: Sergio R on 8 May 2019
Hello, in a ThingSpeak channel, I am reading every one second the information of two current signals (I have the licensed application).
I currently have a MATLAB Analysis routine that adds those two signals and writes, on the same channel, the result of that sum. In the routine I can check that effectively if the sum of the two channels is being done.
I do that now with a good result but my problem is that the channel is not updated except when I run MATLAB Analysis.
How can I make the channel automatically update every second?
-------------------------------------------------------------------------------
This is my routine:
readChannelID = 123;
readAPIKey = 'XXX';
writeChannelID = 123;
writeAPIKey = 'YYY';
%%%%%%%%%%%%%%%%%%%%%% CALCULO DE CORRIENTE %%%%%%%%%%%%%%%%%%%%%%
[Cte1, timeStamp] = thingSpeakRead(readChannelID,'Fields',1,'numPoints', 2, 'ReadKey', readAPIKey);
anyMissingValues = sum(isnan(Cte1));
if sum(anyMissingValues) > 0
missingValueIndex = find(~sum(isnan(Cte1),2));
cleanCte1 = Cte1(missingValueIndex, :);
cleanTimeStamps = timeStamp(missingValueIndex);
else
cleanCte1 = Cte1;
cleanTimeStamps = timeStamp;
end
[Cte2, timeStamp] = thingSpeakRead(readChannelID,'Fields',4,'numPoints', 2, 'ReadKey', readAPIKey);
anyMissingValues = sum(isnan(Cte2));
if sum(anyMissingValues) > 0
missingValueIndex = find(~sum(isnan(Cte2),2));
cleanCte2 = Cte2(missingValueIndex, :);
cleanTimeStamps = timeStamp(missingValueIndex);
else
cleanCte2 = Cte2;
cleanTimeStamps = timeStamp;
end
Corriente = round([cleanCte1 + cleanCte2],1);
display (Corriente, 'Corriente')
%%%%%%%%%%%%%%%%%%%%%% VOLTAJE %%%%%%%%%%%%%%%%%%%%%%
[Voltaje, timeStamp] = thingSpeakRead(readChannelID,'Fields',2,'numPoints', 2, 'ReadKey', readAPIKey);
anyMissingValues = sum(isnan(Voltaje));
if sum(anyMissingValues) > 0
missingValueIndex = find(~sum(isnan(Voltaje),2));
cleanVoltaje = Voltaje(missingValueIndex, :);
cleanTimeStamps = timeStamp(missingValueIndex);
else
cleanVoltaje = Voltaje;
cleanTimeStamps = timeStamp;
end
display (cleanVoltaje, 'Voltaje')
%%%%%%%%%%%%%%%%%%%%%% CALCULO DE POTENCIA %%%%%%%%%%%%%%%%%%%%%%
Potencia = round([Corriente * cleanVoltaje],0)
%%%%%%%%%%%%%%%%%%%%%% CALCULO DE ENERGIA %%%%%%%%%%%%%%%%%%%%%%
[Energia1, timeStamp] = thingSpeakRead(readChannelID,'Fields',3,'numPoints', 2, 'ReadKey', readAPIKey);
anyMissingValues = sum(isnan(Energia1));
if sum(anyMissingValues) > 0
missingValueIndex = find(~sum(isnan(Energia1),2));
cleanEnergia1 = Energia1(missingValueIndex, :);
cleanTimeStamps = timeStamp(missingValueIndex);
else
cleanEnergia1 = Energia1;
cleanTimeStamps = timeStamp;
end
[Energia2, timeStamp] = thingSpeakRead(readChannelID,'Fields',5,'numPoints', 2, 'ReadKey', readAPIKey);
anyMissingValues = sum(isnan(Energia2));
if sum(anyMissingValues) > 0
missingValueIndex = find(~sum(isnan(Energia2),2));
cleanEnergia2 = Energia2(missingValueIndex, :);
cleanTimeStamps = timeStamp(missingValueIndex);
else
cleanEnergia2 = Energia2;
cleanTimeStamps = timeStamp;
end
Energia = [cleanEnergia1 + cleanEnergia2];
display (Energia, 'Energia')
%%%%%%%%%%%%%%%%% Write the results in fields 6, 7 and 8 of the same channel %%%%%%%%%%%%%%%%%%%%
thingSpeakWrite(writeChannelID, 'Fields', [6,7,8], 'Values',...
[Corriente, Potencia, Energia],'WriteKey',writeAPIKey);
OUTPUT:
Corriente = 3.4000
Voltaje = 116
Potencia = 394
Energia = 0.0040

Accepted Answer

Sergio R
Sergio R on 8 May 2019
I have followed your advice and it actually works. The channel is already updated automatically.
thanks for your help

More Answers (2)

Hans Scharler
Hans Scharler on 7 May 2019
I would write to a second ThingSpeak channel instead of writing data back to the same channel. The reason is that ThingSpeak will overwrite other fields with nulls for the fields that do not have a value. I think that you are writing to the 6,7,8 fields, then your channel updates and overrides their data with nulls.
Also, you can read an entire channel's worth of data in one thingSpeakRead request. This will speed up your script.
  2 Comments
Hans Scharler
Hans Scharler on 7 May 2019
I see. This means that the MATLAB code is not scheduled to run automatically. At the bottom of the page, there is a place to add a TimeControl or a React. TimeControl will schedule your code to run and React will run the code based on a condition.

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Sergio R
Sergio R on 7 May 2019
Edited: Sergio R on 7 May 2019
True. But the minimum control time is every 5 minutes. I need it to be every 1 or 2 seconds.
How can I make it update automatically every 1 or 2 seconds?
  1 Comment
Hans Scharler
Hans Scharler on 8 May 2019
You can use React. Select "On data insert". This will cause the MATLAB code to run every time data gets sent to ThingSpeak.

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