How to check if mqtt has not received a message in the past 30m

Configuration
1

Hi,
I have a topic that received some values for each 10s.
How can I write automation that reads the last message received time and compare with the current to get how long the time has passed?
My idea is to generate an alarm (telegram message) when a topic hasn’t received a message in the past 30m.

2

Assuming the message actually updated the entity, the entity has a lastchanged/updated and you could compare this to ‘now’?

3

You might want to consider using the expire_after option.

Using expire_after, if the sensor receives no updates after 30 minutes, its state changes to unavailable. You can make a simple automation, with a State Trigger, that sends you a notification when the sensor’s state changes to unavailable.

4

something like that?

alias: Grow tend - Alarm when no reading was received
description: ''
trigger:
  - platform: state
    entity_id: sensor.ph
    attribute: expire_after
    to: unavailable
condition: []
action:
  - service: telegram_bot.send_message
    data:
      message: 🚨 ATTENTION!! 🚨 NO NEW MESSAGES WERE RECEIVED IN THE LAST 30s!!
      target: my_target
mode: single
5

No, expire_after is a configuration option for an MQTT Sensor (as shown in the documentation). Ensure you add it to the sensor’s configuration and then remove attribute: expire_after from your automation’s State Trigger.

6

It’s there:

sensor:
  - platform: mqtt
    state_topic: 'sensors/hydroponics-kit/ph'
    name: 'PH'
    value_template: "{{ value_json }}"
    unit_of_measurement: 'PH'
    expire_after: 30

So the value of this sensor will become unavailable that’s right?

7

The time unit for expire_after is seconds. If you want it to expire after 30 minutes you need to set it to 1800 which is 30 x 60.

  - platform: mqtt
    state_topic: 'sensors/hydroponics-kit/ph'
    name: 'PH'
    value_template: "{{ value_json }}"
    unit_of_measurement: 'PH'
    expire_after: 1800

The automation triggers when the sensor’s state value changes to unavailable.

alias: Grow tend - Alarm when no reading was received
description: ''
trigger:
  - platform: state
    entity_id: sensor.ph
    to: unavailable
condition: []
action:
  - service: telegram_bot.send_message
    data:
      message: 🚨 ATTENTION!! 🚨 NO NEW MESSAGES WERE RECEIVED IN THE LAST 30s!!
      target: my_target
mode: single
1 Like
8

Thank you very much!

1 Like
9 
  - platform: template
    name: User1 weight
    id: weight_user1
    unit_of_measurement: 'kg'
    icon: mdi:weight-kilogram
    accuracy_decimals: 2

What if my data is coming from ESPHome? Basically I want an alert if no data for last 3 hrs etc

10

This 2 year-old topic was originally about an MQTT Sensor which offers an expire_after option. I am much less familiar with the configuration possibilities of an ESPHome device so you can either look through its documentation for something equivalent to expire_after or wait for someone else (more experienced with ESPHome) to answer your question.