Usin Thingspeak to control a remote device?

Hello,

I am exploring Thingspeak features. I have successfully set up an Arduino board with sensors to send messages and display the channel on the Dashboard. It seems to me, however, that the reverse is not possible, i.e. to send messages to Arduino in order to control it. In fact the four widgets available are only supposed to receive data, not to send them. Is this because I have a free account or is it a feature of Thingspeak? As an example, Arduino IoT offers both possibilities.

Thanks

Giovanni

Answer 1

[Vinod]

Hello @Giovanni - there are a couple of ways you can use ThingSpeak to control a device.

• Use the Talkback app. Here's an example.
• Have the device subscribe to a ThingSpeak channel using MQTT and publish messages to a field on the channel. Here's an example.

A few points to note:

1. The Talkback app requires your device to poll the ThingSpeak API, and it must have sufficient delays built in so your device doesn't hit server-side rate limits. In general, polling is less efficient than "push" messages. I would strongly recommend the MQTT publish/subscribe pattern as it is more efficient for your device and for ThingSpeak servers.
2. With a free account, you may update a channel only once every 15s. So, if you are looking for some means of "real-time" control, you will want to purchase a license so you can update a channel up to once per second.
3. If your "real-time" needs are faster than once a second, I'd recommend considering if the control action can be done on the device without needing the cloud. Cloud connections add latency and will generally be significantly slower than any control logic implemented on the device. Consider building a closed-loop control system using Simulink and generating code for your embedded hardware.

[Giovanni]

Thank you, Vinod. It's clear now

Giovanni

Answer 2

[Christopher Stapels]

Good examples, @Vinod Also, this example shows specifically remote physical control though unfotunately uses esp8266. Still, I think it is another good related example, and it is similar.