A while ago I built a Modbus RTU to Modbus TCP Gateway based on a Beaglebone Green and a RS485 Cape (check my blog post from back then). It worked, but stoped working from time to time and I decided to fix that issue a few weeks ago. I updated the OS on the Beaglebone and realized that so many things changed since my initial implementation that I didn’t want to invest to much time.
So I decided to use a USB to RS485 converter and plug that directly into my server and control the ventilation unit directly from Home-Assistant.
Modbus configuration 🔗
configuration.yaml
modbus:
name: ventilation_unit
type: serial
method: rtu
port: /dev/ttyUSB0
baudrate: 19200
stopbits: 1
bytesize: 8
parity: E
Nothing special here, the port must match the USB converter and the user that runs HA must have the rights to access the port (I had to add it to the uucp group).
ventilation.yaml
- platform: modbus
registers:
- name: einlass_ventilator
hub: ventilation_unit
unit_of_measurement: '%'
slave: 1
register: 102
register_type: input
- name: Auslass Ventilator
hub: ventilation_unit
unit_of_measurement: '%'
slave: 1
register: 103
register_type: input
- name: Alarm
hub: ventilation_unit
slave: 1
register: 101
register_type: input
- name: CO2
hub: ventilation_unit
unit_of_measurement: 'PPM'
slave: 1
register: 10
register_type: input
- name: Temperatur Zuluft
hub: ventilation_unit
unit_of_measurement: '°C'
slave: 1
register: 0
register_type: input
scale: 0.1
offset: -30.0
precision: 1
- name: Temperatur Frischluft
hub: ventilation_unit
unit_of_measurement: '°C'
slave: 1
register: 2
register_type: input
scale: 0.1
offset: -30.0
precision: 1
- name: Temperatur Fortluft
hub: ventilation_unit
unit_of_measurement: '°C'
slave: 1
register: 3
register_type: input
scale: 0.1
offset: -30.0
precision: 1
- name: Temperatur Abluft
hub: ventilation_unit
unit_of_measurement: '°C'
slave: 1
register: 6
register_type: input
scale: 0.1
offset: -30.0
precision: 1
I set up the registers that I want to read as documented in the [Modbus PDF from Alpha Innotec]({static}/blog/2019/lg327TB-hass-knx/Modbus OPT250 - 20130813.pdf) (they sent it to me years ago when I asked them).
The only think that’s important is that the hub matches the name defined in configuration.yaml.
The only kind of special thing here is the alram. It gives me a binary representation of all alarms. I used template binary sensors to decode them.
- platform: template
sensors:
alarm_external_stop:
friendly_name: "Alarm Externer Stop"
value_template: >-
{{ states('sensor.alarm')|int|bitwise_and(1) }}
alarm_main_filter:
friendly_name: "Hauptfilter"
value_template: >-
{{ states('sensor.alarm')|int|bitwise_and(2) }}
alarm_high_preasure:
friendly_name: "Hochdruck"
value_template: >-
{{ states('sensor.alarm')|int|bitwise_and(4) }}
alarm_frost:
friendly_name: "Frost"
value_template: >-
{{ states('sensor.alarm')|int|bitwise_and(8) }}
alarm_communication_error:
friendly_name: "Kommunikationsfehler"
value_template: >-
{{ states('sensor.alarm')|int|bitwise_and(16) }}
alarm_external_filter:
friendly_name: "Externer Filter"
value_template: >-
{{ states('sensor.alarm')|int|bitwise_and(32) }}
alarm_fan_speed:
friendly_name: "Lüfter Geschwindigkeit"
value_template: >-
{{ states('sensor.alarm')|int|bitwise_and(64) }}
That enabled me to get the sensor data into HA:
Snippet from the Lovelace UI config
- entities:
- entity: sensor.einlass_ventilator
icon: 'mdi:fan'
name: Einlass Ventilator
- entity: sensor.auslass_ventilator
icon: 'mdi:fan'
name: Auslass Ventilator
- entity: sensor.co2
icon: 'mdi:grain'
name: Kohlendioxyd
- entity: sensor.temperatur_frischluft
icon: 'mdi:thermometer'
name: Temperatur Frischluft
- entity: sensor.temperatur_zuluft
icon: 'mdi:thermometer'
name: Temperatur Zuluft
- entity: sensor.temperatur_abluft
icon: 'mdi:thermometer'
name: Temperatur Abluft
- entity: sensor.temperatur_fortluft
icon: 'mdi:thermometer'
name: Temperatur Fortluft
- entity: binary_sensor.alarm_external_stop
icon: 'mdi:alert-decagram-outline'
name: Alarm externer Stop
- entity: binary_sensor.alarm_main_filter
icon: 'mdi:alert-decagram-outline'
name: Alarm Hauptfilter
- entity: binary_sensor.alarm_high_preasure
icon: 'mdi:alert-decagram-outline'
name: Alarm Hochdruck
- entity: binary_sensor.alarm_frost
icon: 'mdi:alert-decagram-outline'
name: Alarm Frost
- entity: binary_sensor.alarm_communication_error
icon: 'mdi:alert-decagram-outline'
name: Alarm Kommunikation
- entity: binary_sensor.alarm_external_filter
icon: 'mdi:alert-decagram-outline'
name: Alarm Externer Filter
- entity: binary_sensor.alarm_fan_speed
icon: 'mdi:alert-decagram-outline'
name: Alarm Lüftergeschwindigkeit
show_header_toggle: false
title: Lüftungsanlage
type: entities
Writing ventilation levels 🔗
So I was able to read but not to write. I asked in the discord channel how to achieve that and was pointed towards the entity-button card.
Unfortunately that card requires a entity_id, so I decided to create kind of a dummy entity.
confguration.yaml
input_boolean:
stufe:
name: "Lüftung Stufe"
With that I created a horizontal-stack of entity-button cards
Snippet from the Lovelace UI config
- cards:
- entity: input_boolean.stufe
hold_action:
action: none
icon: 'mdi:fan-off'
name: Aus
show_icon: true
show_name: true
tap_action:
action: call-service
service: modbus.write_register
service_data:
address: 100
hub: ventilation_unit
unit: 1
value: 0
type: entity-button
- entity: input_boolean.stufe
hold_action:
action: none
icon: 'mdi:numeric-1-box'
name: Stufe 1
show_icon: true
show_name: true
tap_action:
action: call-service
service: modbus.write_register
service_data:
address: 100
hub: ventilation_unit
unit: 1
value: 1
type: entity-button
- entity: input_boolean.stufe
hold_action:
action: none
icon: 'mdi:numeric-2-box'
name: Stufe 2
show_icon: true
show_name: true
tap_action:
action: call-service
service: modbus.write_register
service_data:
address: 100
hub: ventilation_unit
unit: 1
value: 2
type: entity-button
- entity: input_boolean.stufe
hold_action:
action: none
icon: 'mdi:numeric-3-box'
name: Stufe 3
show_icon: true
show_name: true
tap_action:
action: call-service
service: modbus.write_register
service_data:
address: 100
hub: ventilation_unit
unit: 1
value: 3
type: entity-button
- entity: input_boolean.stufe
hold_action:
action: none
icon: 'mdi:numeric-4-box'
name: Stufe 4
show_icon: true
show_name: true
tap_action:
action: call-service
service: modbus.write_register
service_data:
address: 100
hub: ventilation_unit
unit: 1
value: 4
type: entity-button
type: horizontal-stack
That results in 5 buttons that when clicked call a service provided by the Modbus integration that writes a certain value into a Modbus register and therby sets the speed of the ventilators.
KNX integration 🔗
With my old solution I had two buttons on a KNX Glas button that allowd me to control the level without using the phone. The control was actually done by my Loxone Miniserver that has a KNX interface, but I wanted to reduce the amount of things that this device does because I need a Windows Software to make changes to it and that sucks :-)
Also I want HA to be able to react on KNX telegrams, so here is how I solved this last task.
First I need to configure that the KNX integration fires an event whenever a KNX telegram is received. For the moment I decided to not set any filters.
configuration.yaml
knx:
fire_event: true
fire_event_filter: ["*"]
Then I created an automation that reacts on a certain KNX Group Address with a data value of 1
automation.yaml
- alias: 'Set ventilation level to 4 via KNX Switch'
trigger:
platform: event
event_type: knx_event
event_data:
address: "6/1/162"
data: 1
action:
- service: modbus.write_register
data:
address: 100
hub: ventilation_unit
unit: 1
value: 4
- alias: 'Set ventilation level to 2 via KNX Switch'
trigger:
platform: event
event_type: knx_event
event_data:
address: "6/1/161"
data: 1
action:
- service: modbus.write_register
data:
address: 100
hub: ventilation_unit
unit: 1
value: 2
The trigger ist set to knx_event and the event_data is like a filter to only react on a given Group address and data. The action calls the modbus.write_register service and sends the right values to the Modbus registers of the ventilation unit.