2024.11.0
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MQTT binary sensor

The mqtt binary sensor platform uses an MQTT message received to set the binary sensor’s state to on, off or unknown.

The state will be updated only after a new message is published on state_topic matching payload_on, payload_off or None. If these messages are published with the retain flag set, the binary sensor will receive an instant state update after subscription and Home Assistant will display the correct state on startup. Otherwise, the initial state displayed in Home Assistant will be unknown.

Stateless devices such as buttons, remote controls etc are better represented by MQTT device triggers than by binary sensors.

Configuration

The mqtt binary sensor platform optionally supports a list of availability topics to receive online and offline messages (birth and LWT messages) from the MQTT device. During normal operation, if the MQTT sensor device goes offline (i.e., publishes payload_not_available to an availability topic), Home Assistant will display the binary sensor as unavailable. If these messages are published with the retain flag set, the binary sensor will receive an instant update after subscription and Home Assistant will display the correct availability state of the binary sensor when Home Assistant starts up. If the retain flag is not set, Home Assistant will display the binary sensor as unavailable when Home Assistant starts up. If no availability topic is defined, Home Assistant will consider the MQTT device to be available and will display its state.

To use an MQTT binary sensor in your installation, add the following to your configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI. [Learn more] file:

# Example configuration.yaml entry
mqtt:
  - binary_sensor:
      state_topic: "home-assistant/window/contact"

Configuration Variables

Looking for your configuration file?
availability list (Optional)

A list of MQTT topics subscribed to receive availability (online/offline) updates. Must not be used together with availability_topic.

payload_available string (Optional, default: online)

The payload that represents the available state.

payload_not_available string (Optional, default: offline)

The payload that represents the unavailable state.

topic string Required

An MQTT topic subscribed to receive availability (online/offline) updates.

value_template template (Optional)

Defines a template to extract device’s availability from the topic. To determine the devices’s availability result of this template will be compared to payload_available and payload_not_available.

availability_mode string (Optional, default: latest)

When availability is configured, this controls the conditions needed to set the entity to available. Valid entries are all, any, and latest. If set to all, payload_available must be received on all configured availability topics before the entity is marked as online. If set to any, payload_available must be received on at least one configured availability topic before the entity is marked as online. If set to latest, the last payload_available or payload_not_available received on any configured availability topic controls the availability.

availability_template template (Optional)

Defines a template to extract device’s availability from the availability_topic. To determine the devices’s availability result of this template will be compared to payload_available and payload_not_available.

availability_topic string (Optional)

The MQTT topic subscribed to receive birth and LWT messages from the MQTT device. If availability is not defined, the binary sensor will always be considered available and its state will be on, off or unknown. If availability is defined, the binary sensor will be considered as unavailable by default and the sensor’s initial state will be unavailable. Must not be used together with availability.

device map (Optional)

Information about the device this binary sensor is a part of to tie it into the device registry. Only works when unique_id is set. At least one of identifiers or connections must be present to identify the device.

configuration_url string (Optional)

A link to the webpage that can manage the configuration of this device. Can be either an http://, https:// or an internal homeassistant:// URL.

connections list (Optional)

A list of connections of the device to the outside world as a list of tuples [connection_type, connection_identifier]. For example the MAC address of a network interface: "connections": [["mac", "02:5b:26:a8:dc:12"]].

hw_version string (Optional)

The hardware version of the device.

identifiers list | string (Optional)

A list of IDs that uniquely identify the device. For example a serial number.

manufacturer string (Optional)

The manufacturer of the device.

model string (Optional)

The model of the device.

model_id string (Optional)

The model identifier of the device.

name string (Optional)

The name of the device.

serial_number string (Optional)

The serial number of the device.

suggested_area string (Optional)

Suggest an area if the device isn’t in one yet.

sw_version string (Optional)

The firmware version of the device.

via_device string (Optional)

Identifier of a device that routes messages between this device and Home Assistant. Examples of such devices are hubs, or parent devices of a sub-device. This is used to show device topology in Home Assistant.

device_class string (Optional)

Sets the class of the device, changing the device state and icon that is displayed on the frontend. The device_class can be null.

enabled_by_default boolean (Optional, default: true)

Flag which defines if the entity should be enabled when first added.

encoding string (Optional, default: utf-8)

The encoding of the payloads received. Set to "" to disable decoding of incoming payload.

entity_category string (Optional)

The category of the entity. When set, the entity category must be diagnostic for sensors.

entity_picture string (Optional)

Picture URL for the entity.

expire_after integer (Optional)

If set, it defines the number of seconds after the sensor’s state expires, if it’s not updated. After expiry, the sensor’s state becomes unavailable. Default the sensors state never expires.

force_update boolean (Optional, default: false)

Sends update events (which results in update of state object’s last_changed) even if the sensor’s state hasn’t changed. Useful if you want to have meaningful value graphs in history or want to create an automation that triggers on every incoming state message (not only when the sensor’s new state is different to the current one).

icon icon (Optional)

Icon for the entity.

json_attributes_template template (Optional)

Defines a template to extract the JSON dictionary from messages received on the json_attributes_topic. Usage example can be found in MQTT sensor documentation.

json_attributes_topic string (Optional)

The MQTT topic subscribed to receive a JSON dictionary payload and then set as sensor attributes. Usage example can be found in MQTT sensor documentation.

name string (Optional, default: MQTT binary sensor)

The name of the binary sensor. Can be set to null if only the device name is relevant.

object_id string (Optional)

Used instead of name for automatic generation of entity_id

off_delay integer (Optional)

For sensors that only send on state updates (like PIRs), this variable sets a delay in seconds after which the sensor’s state will be updated back to off.

payload_available string (Optional, default: online)

The string that represents the online state.

payload_not_available string (Optional, default: offline)

The string that represents the offline state.

payload_off string (Optional, default: OFF)

The string that represents the off state. It will be compared to the message in the state_topic (see value_template for details)

payload_on string (Optional, default: ON)

The string that represents the on state. It will be compared to the message in the state_topic (see value_template for details)

platform string Required

Must be binary_sensor. Only allowed and required in MQTT auto discovery device messages.

qos integer (Optional, default: 0)

The maximum QoS level to be used when receiving and publishing messages.

state_topic string Required

The MQTT topic subscribed to receive sensor’s state. Valid states are OFF and ON. Custom OFF and ON values can be set with the payload_off and payload_on config options.

unique_id string (Optional)

An ID that uniquely identifies this sensor. If two sensors have the same unique ID, Home Assistant will raise an exception. Required when used with device-based discovery.

value_template template (Optional)

Defines a template that returns a string to be compared to payload_on/payload_off or an empty string, in which case the MQTT message will be removed. Remove this option when payload_on and payload_off are sufficient to match your payloads (i.e no preprocessing of original message is required).

Examples

In this section, you will find some real-life examples of how to use this sensor.

Full configuration with JSON data

This is an example of a configuration where the state is extracted from a JSON formatted MQTT message. To test, you can use the command line tool mosquitto_pub shipped with mosquitto or the mosquitto-clients package to send MQTT messages.

To set the state of the binary sensor manually:

mosquitto_pub -h 127.0.0.1 -t home-assistant/window/availability -m "online"
mosquitto_pub -h 127.0.0.1 -t home-assistant/window/contact -m '{"state":"ON"}'
mosquitto_pub -h 127.0.0.1 -t home-assistant/window/contact -m '{"state":"OFF"}'

The example below shows a full configuration for a binary sensor:

# Example configuration.yaml entry
mqtt:
  - binary_sensor:
      name: "Window Contact Sensor"
      state_topic: "home-assistant/window/contact"
      payload_on: "ON"
      availability:
        - topic: "home-assistant/window/availability"
          payload_available: "online"
          payload_not_available: "offline"
      qos: 0
      device_class: opening
      value_template: "{{ value_json.state }}"

Toggle the binary sensor each time a message is received on state_topic 

# Example configuration.yaml entry
mqtt:
  - binary_sensor:
      state_topic: "lab_button/cmnd/POWER"
      value_template: "{%if is_state(entity_id,\"on\")-%}OFF{%-else-%}ON{%-endif%}"

Get the state of a device with ESPEasy

Assuming that you have flashed your ESP8266 unit with ESPEasy. Under “Config” is a name (“Unit Name:”) set for your device (here it’s “bathroom”). A configuration for a “Controller” for MQTT with the protocol “OpenHAB MQTT” is present and the entries (“Controller Subscribe:” and “Controller Publish:”) are adjusted to match your needs. In this example, the topics are prefixed with “home”. Also, add a “Switch Input” in the “Devices” tap with the name “switch” and “button” as value.

As soon as the unit is online, you will get the state of the attached button.

home/bathroom/status Connected
...
home/bathroom/switch/button 1

The configuration will look like the example below:

# Example configuration.yaml entry
mqtt:
  - binary_sensor:
      name: Bathroom
      state_topic: "home/bathroom/switch/button"
      payload_on: "1"
      payload_off: "0"