Patform Template - how can I get previous state (its called from_state in actions)

@rak wrote:

Hi guys,

switching from OH to HA. over the weekend. Steep learning curve behind me and ahead. I am really impressed by HA. One thing I am banging my head around for 6h now and i Need your help.

I have a sensor which gets every minute an update. Its a counter which counts 1/250 kWh and its just a number. I get it from KNX, but that should not matter.

With a sensor template I calculate this into kWh ( a number i can read and see on my meter).

- platform: template
  sensors:
    counter_power_kwh:
      friendly_name: "Strom"
      unit_of_measurement: 'kWh'
      value_template: >
        {{ (states("sensor.counter_power_impulse")|float - 16369685.0) / 250.0 + 35344.6 }}

I have another item which gets updated each time the above one gets updated. Target is to calculate delta kWh and delta T in seconds.

I checked in debugging. When I replace the from_state with a copy paste value from the previous run I get reasonable numbers (480W), however in HA I get 0.0 because from_state is always 0.0.

- platform: template
  sensors:
    counter_power_consumption:
      unit_of_measurement: 'W'
      value_template: >
        {% set delta_kWh = (states("sensor.counter_power_kwh")|float) - (states('states.sensor.counter_power_kwh.from_state')|float) %}
        {% set delta_s = (as_timestamp(now()) - as_timestamp(states.sensor.counter_power_kwh.last_changed)) %}
        {% if states('states.sensor.counter_power_kwh.from_state')|float == 0.0 %}
          0.0
        {% else %}
          {{ (delta_kWh / delta_s) * 1000.0 * 3600.0 }}
        {% endif %}

Can someone point me into the right direction? I have

• an entity whith increasing kWh
• I want a regular check how much kWh were consumed.
• Say every 6min would be ok.It really does not matter how often.
• with that delta kWh and delta T I can calculate the power consumption.
• I need only delta from sensor (current and previous value).

How can I get this done? Is an automation the right way? How do I set a sensor item from an action?

I am stuck and need some sleep.

Thank you for reading so far.

Regards
Ralf

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