MQTT Binary Sensor


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

The state will be updated only after a new message is published on state_topic matching payload_on or payload_off. 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.yaml file:

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

Configuration Variables

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.

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 through MQTT discovery and when unique_id is set.

connections list | map (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'].

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.

name string (Optional)

The name of the device.

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.

expire_after integer (Optional)

Defines the number of seconds after the sensor’s state expires, if it’s not updated. After expiry, the sensor’s state becomes unavailable.

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).

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.

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)

qos integer (Optional, default: 0)

The maximum QoS level to be used when receiving messages.

state_topic string Required

The MQTT topic subscribed to receive sensor’s state.

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.

value_template string (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. Available variables: entity_id. Remove this option when ‘payload_on’ and ‘payload_off’ are sufficient to match your payloads (i.e no pre-processing 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
binary_sensor:
  - platform: mqtt
    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
binary_sensor:
  - platform: mqtt
    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
binary_sensor:
  - platform: mqtt
    name: Bathroom
    state_topic: "home/bathroom/switch/button"
    payload_on: "1"
    payload_off: "0"