ThingSpeak Read

Read data stored in ThingSpeak channel

Since R2021b

Add-On Required: This feature requires the Simulink Coder Support Package for STMicroelectronics Nucleo Boards add-on.

• 

Libraries:
Simulink Coder Support Package for STMicroelectronics Nucleo Boards / STM32F7
Simulink Coder Support Package for STMicroelectronics Nucleo Boards / STM32H7

Description

The ThingSpeak Read block reads data from the ThingSpeak™ channel on the ThingSpeak.com website. The hardware must be connected to the Internet. The block outputs Scalar single and ASCII Vector data.

ThingSpeak is an IoT analytics platform service that allows you to aggregate, visualize, and analyze live data streams in the cloud. You can send data to ThingSpeak from your devices, create instant visualizations of live data, and send alerts using web services. With MATLAB^® analytics inside ThingSpeak, you can write and execute MATLAB code to perform preprocessing, visualizations, and analyses.

For more information on how to use ThingSpeak, see Apps, Plugins, or Tutorials.

Limitations

• The ThingSpeak Write and ThingSpeak Read blocks take a minimum of 700 ms for execution when you run the model in external mode. If the overall model execution time when you run the model in external mode exceeds 2 s, there can be sporadic disconnects. There is no such limitation if you run the model in the Build, load and run mode.

Ports

Output

Data — Data read from specified field of ThingSpeak channel

scalar

At each time step, the port outputs the data read from the field specified in the Field Number parameter.

Data Types: single

Status — Status of each read request

scalar

The port outputs the status of each read request as mentioned in the following table:

Return status codes

Status	Description
200	OK or Success
-301	Failed to connect to ThingSpeak
-303	Unable to parse response from ThingSpeak
-304	No response from server within timeout

Dependencies

This port appears only when you select the Output Status parameter.

Data Types: single

Received length — Actual length of the received ASCII vector

vector

The Received length port outputs the actual length of the received ASCII vector of the field.

Dependencies

This port appears only when you select the Received Field Length parameter.

Data Types: uint8

Parameters

Channel ID — Channel ID from which block reads data

65531 (default) | positive integer

Specify the channel ID from which the block reads data.

If you do not know the channel ID of your channel:

1. Sign In to ThingSpeak using your MathWorks^® Account.

2. Select Channels > My Channels.

3. Select the channel from which to read data.

4. Click the Channel Settings tab.

5. Copy the channel ID from the Channel ID parameter.

   

6. Open the ThingSpeak Read block in your model and paste the copied ID to the Channel ID parameter.

Channel access — Sharing settings of channel

Public (default) | Private

Specify if your channel is private or public.

If you do not know the sharing settings of your channel:

1. Sign In to ThingSpeak using your MathWorks Account.

2. Select Channels > My Channels.

3. Select the channel to get the sharing status.

4. Click the Sharing tab. Use the option selected in the tab to set Channel Access.

   • Keep channel view private: Set Channel Access to Private. Only you can view the channel data.

   • Share channel view with everyone: Set Channel Access to Public. Anyone browsing the ThingSpeak website can view the channel data.

   • Share channel view only with the following users: Set Channel Access to Private. Users who have access to shared channels can see only the private view of a channel; they cannot add channels, see alerts, or see license information.

   

Field number — Field from which block reads data

1 (default) | integer between 1 and 8

Select a field of the ThingSpeak channel from which the block reads data.

Output Type — Select ThingSpeak read output type

Numeric data (single) (default) | ASCII (uint8)

When you select Output type as Numeric data (single) then the block outputs Scalar single value of the data of the selected field.

When you select Output type as ASCII vector (uint8) then the block outputs ASCII vector of the data of the selected field.

Output Length — Specify ThingSpeak read output length

1 (default) | Any positive integer

Specify the output length for the ThingSpeak Read block.

Dependencies

To enable Output Length parameter, set Output type to ASCII vector (uint8).

Received Field Length — Select received field length

off (default) | on

When you select the Received Field Length parameter, the block configures an output port, Received Length. The port outputs the actual length of the received ASCII vector of the field.

Dependencies

To enable Received Field Length parameter, set Output type to ASCII vector (uint8).

Output Status — Enable output status

off (default) | on

When you select the Output Status parameter, the block configures an output port, Status. The port outputs the status message.

Sample time — Interval at which block reads data

20 (default) | -1 | nonnegative integer

Specify how often the block reads data from the ThingSpeak channel.

When you set this parameter to -1, Simulink^® determines the best sample time for the block based on the block context within the model.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2021b