Subscribe to a Channel Feed

Subscribe to updates from channel feed with MQTT

ThingSpeak™ MQTT supports only QoS 0. For more information,see Server Response for Connections.

Syntax

channels/<channelID>/subscribe

Description

channels/<channelID>/subscribe subscribes to updates to a channel feed. Replace <channelID> with the channel ID and <format> with the format of the return message.

Input Arguments

<channelID> — channelID for the subscription target

integer

Channel ID for the subscription target, specified as a positive integer.

Limitations

• Each ThingSpeak license type allows a different number of concurrent MQTT subscriptions and has different restrictions on the number of messages delivered. For more information, see How to Buy and Frequently Asked Questions.

• MQTT subscriptions do not report updates to the channel from Bulk Write JSON Data or Bulk Write CSV Data.

• ThingSpeak MQTT honors all MQTT disconnect and unsubscribe messages. If you disconnect from the MQTT server, you are automatically unsubscribed from channel updates.

Examples

Configure MQTT X to subscribe to channel updates from your channel 33301 using mqtt3.thingspeak.com and port 1883.

In the New Connection dialog, use the following connection settings, along with client ID, username, and password derived when the MQTT device was created in ThingSpeak:

Name: MyChanName
Client ID: ENTER_MQTT_DEVICE_CLIENT_ID
Host: mqtt://    mqtt3.thingspeak.com
Port: 1883
Username: ENTER_MQTT_DEVICE_USERNAME
Password: ENTER_MQTT_DEVICE_PASSWORD
Clean Session: true (for best performance)

In the New Subscription dialog, use the subscribe topic syntax and settings:

Topic: channels/33301/subscribe
QoS: 0

Now when data is written to the channel, you can observe the messages in the MQTT X client display.

Version History

Introduced in R2017b