Publish to a Channel Field Feed

Publish message to update single channel field

Topic

channels/<channelID>/publish/fields/field<fieldnumber>/<apikey>

Description

channels/<channelID>/publish/fields/field<fieldnumber>/<apikey> publishes messages to the topic to update a channel field. Replace <channelID> with the channel ID, <fieldnumber> with field number that you want to update, and <apikey> with the write API key of the channel. To learn more about configuring your channel, see Channel Properties. Use this method to update a single field in a channel. To update multiple parameters simultaneously, see Payload Parameters.

• Set the PUBLISH messages to a QoS value of 0.

• Set the connection RETAIN flag to 0.

• Set the connection CleanSession flag to 1.

To learn more about these flags, see MQTT v3.1.1 specification.

Input Arguments

<channel id> — channelID for the publish target

(default) (default) | numeric

Channel ID for the publish target, secified as a numeric.

Data Types: uint16 | int16 | int8 | uint8

<apikey> — channel write API Key

Channel write API Key. The value can be found on the Channel Settings > API Keys. This value is different than the MQTT API Key used for connection, and it is different than the channel Read API Key.

Data Types: char

<fieldnumber> — field number of the publish target

1 | 2 | 3 | 4 | 5 | 6 | 7 | 8

Field number of the Publish target, specified as a positive integer

Data Types: uint16 | int16 | int8 | uint8

Payload Parameters

Data to be entered in the specified field of a channel, specified as a string. For example: 100

Examples

Configure MQTT.fx to send a PUBLISH message to update a channel field.

Replace <channelID> with the channel ID and <apikey> with the Write API Key of the channel. This PUBLISH message publishes a value of 45 to field1 of the specified channel.