Topic Structure

Downlink

These topics are used for messages sent from Blynk.Cloud to the device:

• downlink/ds/DATASTREAM: Carries live updates of datastream values or responses to get/ds requests. This ensures that the device is updated with the latest values or specific data it requested.

• downlink/meta/FIELD: Used to send responses for get/meta requests made by the device. This allows the device to update its configuration or status based on cloud-side settings or information.

• downlink/ota/json: Requests from the server to perform a software/firmware update.

• downlink/utc/all/json: Device Time and Timezone information. Used to send response for get/utc/all/json request made by the device.

• downlink/loc/all: Device approximate location. Used to send response for get/loc/all request made by the device.

• downlink/ping: Allows server to ping the device. This message is always published with QOS 1.

• downlink/reboot: Instructs the device to reboot. This can be necessary for applying updates, resetting the device's state, or troubleshooting.

• downlink/redirect: Provides a new MQTT endpoint to which the device should connect. This is part of handling GeoDNS and ensuring the device connects to the most suitable server for improved performance and reliability.

• downlink/diag: Server diagnostics messages.

Uplink

These topics are used for messages sent from the device to Blynk.Cloud:

• info/mcu: Updates the server with device or firmware information. This is essential for device management and monitoring, allowing Blynk.Cloud to keep track of device types, versions, and other critical information.

• ds/DATASTREAM: Updates the value of a specific datastream on the cloud. This is how sensor readings, state changes, or any other device-generated information are communicated to the server.

• batch_ds: Updates values of a multiple datastreams simultaneously. Use this topic if your device rarely sends data in batches.

• ds/DATASTREAM/prop/PROPERTY: Sets a property of the widget associated with a datastream, allowing dynamic changes to how data is displayed or interacted with in the Blynk application.

• event/EVENT: Publishes an event, which can be used for alerts, emails, push notifications, logging, or triggering other server-side actions based on device activities.

• meta/FIELD: Updates a specific metadata field of the device. This can include configuration parameters, or any other contextual information about the device.

• get/ds: Requests the current value of a specific datastream from Blynk.Cloud. This can be used to synchronize device state with server-side values.

• get/meta: Requests metadata values from Blynk.Cloud, useful for devices needing to confirm or update their configuration based on cloud-stored information.

• get/utc/all/json: Requests time-related information, assisting in time synchronization or scheduling tasks based on accurate time data.

• get/loc/all: Requests approximate location information, which can be used for location-based services, astronomical timers or contextual actions based on the device's location.