ThingSpeak Read

Read data stored in ThingSpeak channel

• 

Libraries:
STM32 Microcontroller Blockset / (Legacy) STM32 MBED Based Boards / STM32L475VG-Discovery (B-L475E-IOT01A)
STM32 Microcontroller Blockset / (Legacy) STM32 MBED Based Boards / STM32F7
STM32 Microcontroller Blockset / (Legacy) STM32 MBED Based Boards / STM32H7

Description

The ThingSpeak Read block reads data from the ThingSpeak™ channel on the ThingSpeak.com website.

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.

Examples

Exchanging Wi-Fi Data and Using ThingSpeak with STM32L475VG Discovery Board

Use STM32™ Microcontroller Blockset along with the STM32L475VG Discovery (B-L475E-IOT01A) board to either send and receive TCP messages or send and receive data from a ThingSpeak™ channel. ThingSpeak is a cloud-based MathWorks® internet of things (IoT) analytics platform. For more information, see ThingSpeak.

• Open Model

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.

• When using the WiFi TCP Send, WiFi TCP Receive, ThingSpeak Read, and ThingSpeak Write blocks in a model, the blocks must have the same sample time as the driver code is nonreentrant.

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	No response/ Unable to parse response from ThingSpeak

Dependencies

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

Data Types: single

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.

Programmatic Use

Block Parameter: ChannelID_

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.

   

Programmatic Use

Block Parameter: ChannelAccess_

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.

Programmatic Use

Block Parameter: FieldNumber_

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.

Programmatic Use

Block Parameter: OutputStatus

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.

Programmatic Use

Block Parameter: SampleTime_

Extended Capabilities

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

Version History

Introduced in R2021a