home-assistant.io/source/_components/binary_sensor.mqtt.markdown

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component	MQTT binary sensor	Instructions how to integrate MQTT binary sensors within Home Assistant.	2015-05-30 23:21	true	false	true	true	mqtt.png	Binary Sensor

This mqtt binary sensor implementation uses the MQTT message payload as the sensor value. If messages in this state_topic are published with RETAIN flag, the sensor will receive an instant update with the last known value. Otherwise, the initial state will be off.

To use your MQTT binary sensor in your installation, add the following to your configuration.yaml file:

# Example configuration.yml entry
binary_sensor:
  platform: mqtt
  state_topic: "home-assistant/window/contact"
  name: "MQTT Sensor"
  qos: 0
  payload_on: "ON"
  payload_of: "OFF"
  value_template: '{% raw %}{{ value.x }}{% endraw %}'

Configuration variables:

• state_topic (Required): The MQTT topic subscribed to receive sensor values.
• name (Optional): The name of the sensor. Default is 'MQTT Sensor'.
• qos (Optional): The maximum QoS level of the state topic. Default is 0.
• payload_on (Optional): The payload that represents on state. Default is "ON".
• payload_off (Optional): The payload that represents state. Default is "OFF".
• value_template (Optional): Defines a template to extract a value from the payload.

For a quick check you can use the commandline tools shipped with mosquitto to send MQTT messages. Set the state of your sensor manually:

$  mosquitto_pub -h 127.0.0.1 -t home-assistant/window/contact -m "OFF"