pack more information into a single field

Dear Christopher Stapels, @Christopher Stapels

In my experiment, in total I need to visualize 12 parameters out of 6 different sensors. The outputs of the sensors are as follows.

Sensor 1: one parameter

Sensor 2: one parameter

Sensor 3: one parameter

Sensor 4: three parameters

Sensor 5: four parameters

Sensor 6: two parameters

Is it possible to dedicate each sensor to a field? For example:

Field 1 - Sensor 1: so field 1 will only demonstrate that one parameter

Field 2 - Sensor 2: so field 2 will only demonstrate that one parameter

Field 3 - Sensor 3: so field 2 will only demonstrate that one parameter

Field 4 - Sensor 4: so field 2 will demonstrate that three parameters in one graph

Field 5 - Sensor 5: so field 2 will only demonstrate that four parameters in one graph

Field 6 - Sensor 6: so field 2 will only demonstrate that two parameters in one graph

How can I achieve this?

If possible is there any downside to this?

Additionally, as I saw from your previous response to someone else's question, you said a single field holds up to 255 characters. What does it mean? What does custom visualizations to unpack the field values mean?

Thank your for your interest.

[Walter Roberson]

Is this a question about Simulink ?

How much data is required to store each of the parameters?

[Ismail Bera]

No, I want to do this in ThingSpeak.

I do not know how much data is required to store each of the parameters.

Answer 1

[Christopher Stapels]

Fo the concepts, I really reccomend some time with the documentation.

I would suggest you use multiple channels, this will make your ThingSpeak workflow the most simple.

However, you can succeed using a single channel, but packing values as stated.

The downsides of packing values into fields are that the automatic field plots that come with the channel wont work, and that your process will probably be more britte or prone to breaking - since a change in one sensor may affect others that are packed with it.

A single field update can have up to 255 characters. That means that when you write to a field, you could write something like

https://api.thingspeak.com/update?api_key=xxxxxxxxxxxxxxxx&field1=123456789......(you can write up to 244 more characters here)...

So you can put multiple values with a seperator value like this

https://api.thingspeak.com/update?api_key=xxxxxxxxxxxxxxxx&field1=1234,43.2,245.321

Where the three values are 1234, 43.2, and 245.321

Now thingspeak field plots wont understand that as a number, so you will have to create custom MATLAB visualization to unpack.

If your visualization code, you need to start by getting the date. You would read string data, so use outputformat timetable.

myValues=thingSpeakRead(channel,...,'outputformat','timetable);  
    % MyValues.field1label = "1234, 43.2, and 245.321"

Now you need to split the data and turn it into numbers

theNumbersAsStrings=split(myValues,',');
theNumbers=str2double(theNumbersAsStrings);
...
% plot(theNumbers)  ...and so on

Your actual code will vary depending on how you pack things in.

[Ismail Bera]

Dear Christopher Stapels,

Thank you so much for your answer. I tried the first option, opening multiple channels for the same device. It works fine. I will also try the second option too.

Best regards...