Reliable commands

Configuration
1

I wondering if HA provides a way to make commands reliable. For example, this is my configuration for an Ethernet I/O board:

  - platform: command_line
    switches:
      relay1:
        command_on: echo -n 11 | nc -q 1 192.168.1.100 6722 
        command_off: echo -n 21 | nc -q 1 192.168.1.100 6722
        command_state: echo -n 00 | nc -q 1 192.168.1.100 6722           
        value_template: "{{ value[0:1] == '1' }}"
        friendly_name: Relay 1

Because I specified the command_state value it is used for feedback - i.e. to change the on/off state according to the actual state of the device.

Sometime, it happens that the command_on (or command_off) is sent, but for any reason the board doesn’t toggle its state. This isn’t a fault of HA, of course! But is there a way to tell HA to retry if the command didn’t work?

If I click on a switch in the page I can manually retry after few seconds, but it’s annoying when it happens in automation.

2

As far as I’m aware there is no built-in way to do this.

I’ve had similar issues with my Nest devices, so I came up with a way to do this. It’s a bit more complicated than this use case, so here’s the basic idea:

script:
  relay1_turn_on:
    sequence:
      - service: switch.turn_on
        entity_id: switch.relay1
      - service: script.turn_off
        entity_id: script.relay1_check
      - service: script.relay1_check
        data:
          turn_on: true
  relay1_turn_off:
    sequence:
      - service: switch.turn_off
        entity_id: switch.relay1
      - service: script.turn_off
        entity_id: script.relay1_check
      - service: script.relay1_check
        data:
          turn_on: false
  relay1_check:
    sequence:
      - wait_template: >
          {{ is_state('switch.relay1', 'on' if turn_on else 'off') }}
        timeout: '00:00:05'
        continue_on_timeout: 'true'
      - condition: template
        value_template: >
          {{ is_state('switch.relay1', 'off' if turn_on else 'on') }}
      - service_template: >
          {% if turn_on %}
            script.relay1_turn_on
          {% else %}
            script.relay1_turn_off
          {% endif %}

Use one of the first scripts to turn the switch on or off instead of changing the switch directly. You might need to do a bit more to deal with the situation where the relay’s state never changes like it should (e.g., add a counter to the “loop” and stop if it gets too big and maybe send a notification, etc.)

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3

Got it. Yes, it gets quite complex soon, while it would be simple enough if handled natively.
Right now I’m going to use this approach only for most important switches. I hope the developers will try to get HA more reliable and begin to use feedbacks to close the control-loop!

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