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Subscribe to a Channel Field Feed

Subscribe to channel updates from specific field of channel with MQTT

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ThingSpeak™ MQTT supports only QoS 0.

Syntax

channels/<channelID>/subscribe/fields/field<fieldnumber>
channels/<channelID>/subscribe/fields/+

Description

channels/<channelID>/subscribe/fields/field<fieldnumber> subscribes to updates from a single field of a channel feed. Replace <channelID> with the channel ID and <fieldnumber> with the target field number.

channels/<channelID>/subscribe/fields/+ subscribes to updates to all fields of a channel feed from the specified channel.

Input Arguments

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

Field number of the subscription target, specified as a positive integer.

Limitations

  • Each ThingSpeak license type allows a different number of 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 updates of field1 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/fields/field1
QoS: 0

Now update the field with a publish, and observe the message received in the client from the subscription.

See Also

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