Modbus


modbus is a communication protocol to control PLCs (Programmable Logic Controller) and RTUs (Remote Terminal Unit).

The integration adheres strictly to the protocol specification using pymodbus for the protocol implementation.

The modbus integrationIntegrations connect and integrate Home Assistant with your devices, services, and more. [Learn more] supports all devices adhering to the modbus standard. The communication to the device/devices can be serial (rs-485), TCP, or UDP connections. The modbus integration allows multiple communication channels e.g. a serial port connection combined with one or more TCP connections.

Configuring modbus communication

Configure the modbus communication with modbus devices. This is a general setup needed establish access to the device.

The modbus integration allows you to use multiple connections each with multiple sensors etc.

The modbus integration provides a number of parameters to help communicate with “difficult” devices, these parameters are independent of the type of communication.

To enable this integration, add it to your configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI.[Learn more] file. After changing the configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI.[Learn more] file, restart Home Assistant to apply the changes. To view the changes, go to Settings > Devices & services > Entities.

Configuration Variables

delay integer (Optional, default: 0)

Time to delay sending messages in seconds after connecting. Some modbus devices need a delay of typically 1-2 seconds after connection is established to prepare the communication. If a device does not respond to messages after connecting, then try this parameter. Remark: solely affect the first message.

message_wait_milliseconds integer (Optional)

Time to wait in milliseconds between requests.

Default:

30 for serial connection, 0 for all other connections.

name string Required

Name of this hub. Must be unique.

timeout integer (Optional, default: 5)

Timeout while waiting for a response in seconds.

type list Required

Type of modbus.

tcp

TCP/IP connection with socket framer, used with Ethernet enabled devices.

udp

UDP connection with socket framer, rarely used.

rtuovertcp

TCP/IP connection with rtu framer, used when connection to modbus forwarders.

serial

Serial connection with RTU framer, used with TTY port or USB rs485 converter.

Configuring tcp connection

type: tcp is required. Used for devices providing a TCP/IP interface directly.

Configuration Variables

host string Required

IP address or name of your modbus device, e.g., 192.168.1.1.

port integer Required

Network port for the communication.

Example: typical tcp configuration

# Example yaml: typical tcp connection
modbus:
  - name: modbus_hub
    type: tcp
    host: IP_ADDRESS
    port: 502

Example: full tcp configuration

# Example yaml: full tcp connection
modbus:
  - name: modbus_hub
    type: tcp
    host: IP_ADDRESS
    port: 502

    delay: 0
    message_wait_milliseconds: 30
    timeout: 5

Configuring a TCP-RTU connection

type: rtuovertcp is required. Used for devices providing a TCP/IP interface directly.

This is typically used, when communicating with a modbus-forwarder, a device that has a TCP/IP connection upwards, and one or more serial connections downwards. lets also write more here, to see if the error moves.

Configuration Variables

host string Required

IP address or name of your modbus device, e.g., 192.168.1.1.

port integer Required

Network port for the communication.

Example: typical TCP-RTU configuration

# Example yaml: typical tcp-rtu connection
modbus:
  - name: modbus_hub
    type: rtuovertcp
    host: IP_ADDRESS
    port: 502

Example: full TCP-RTU configuration

# Example yaml: full tcp-rtu connection
modbus:
  - name: modbus_hub
    type: rtuovertcp
    host: IP_ADDRESS
    port: 502

    delay: 0
    message_wait_milliseconds: 30
    timeout: 5

Configuring a UDP connection

type: udp is required. This is rarely used, and only for very special configurations.

Configuration Variables

host string Required

IP address or name of your modbus device, e.g., 192.168.1.1.

port integer Required

Network port for the communication.

Example: typical udp configuration

# Example yaml: typical udp connection
modbus:
  - name: modbus_hub
    type: udp
    host: IP_ADDRESS
    port: 502

Example: full UDP configuration

# Example yaml: full udp connection
modbus:
  - name: modbus_hub
    type: udp
    host: IP_ADDRESS
    port: 502

    delay: 0
    message_wait_milliseconds: 30
    timeout: 5

Configuring serial connection

type: serial is required. This is used for devices providing a serial rs485 interface.

The physical interface is typically a USB serial-rs485 converter or an rs232-rs485 connected to a serial port.

Configuration Variables

baudrate integer Required

Speed of the serial connection, higher speed gives better performance.

bytesize list Required

Data size in bits of each byte.

5

5 bit for data, rarely used.

6

6 bit for data, rarely used.

7

7 bit for data, used for very old devices.

8

8 bit for data, standard.

method list Required

Method of the connection to modbus.

rtu

Binary data transmission preceded by slave id and followed by a crc, standard.

ascii

ASCII data transmission preceded by slave id and followed by a crc, used for few devices.

parity list Required

Parity of the data bytes.

E

Even parity bit.

O

Odd parity bit.

N

No parity bit, standard.

port string Required

Serial port or USB device where your modbus device is connected to your Home Assistant host.

stopbits list Required

Stopbits of the data bytes.

1

1 stop bit.

2

2 stop bits, standard.

Example: typical serial configuration

# Example yaml:  typical serial connection
modbus:
  - name: modbus_hub
    type: serial
    port: /dev/ttyUSB0
    baudrate: 9600
    bytesize: 8
    method: rtu
    parity: E
    stopbits: 1

Example: full serial configuration

# Example yaml: full udp connection
modbus:
  - name: modbus_hub
    type: serial
    port: /dev/ttyUSB0
    baudrate: 9600
    bytesize: 8
    method: rtu
    parity: E
    stopbits: 1

    delay: 0
    message_wait_milliseconds: 30
    timeout: 5

Configuring multiple connections

Multiple connections can freely mix different communications:

# Example yaml: multiple tcp connections
modbus:
  - name: modbus_hub
    type: tcp
    host: IP_ADDRESS_1
    port: 2020

  - name: modbus_hub2
    type: tcp
    host: IP_ADDRESS_2
    port: 502
# Example yaml: tcp connection and serial connection
modbus:
  - name: modbus_hub
    type: tcp
    host: IP_ADDRESS_1
    port: 2020

  - name: modbus_hub2
    type: serial
    port: /dev/ttyUSB0
    baudrate: 9600
    bytesize: 8
    method: rtu
    parity: E
    stopbits: 1

Configuring modbus entities

modbus entities are grouped below each modbus communication entry.

REMARK Each modbus device must have at least 1 entity defined, otherwise the integration will not be loaded.

Please refer to Parameter usage for conflicting parameters.

All modbus entities have the following parameters:

Configuration Variables

address integer Required

Address of coil/register.

name string Required

Name of the entity which must be unique within the entity type.

scan_interval integer (Optional, default: 15)

Update interval in seconds. scan_interval = 0 for no polling. Entities are read shortly after startup and then according to scan_interval. Remark, when restarting HA the last known value is restored.

slave integer (Optional, default: 0)

Identical to device_address

device_address integer (Optional, default: 0)

Id of the device. Used to address multiple devices on a rs485 bus or devices connected to a modbus repeater.

unique_id string (Optional)

ID that uniquely identifies this entity. Slaves will be given a unique_id of <<unique_id>>_<<slave_index>>. If two enities have the same unique ID, Home Assistant will raise an exception.

Example: entities grouping

# Example yaml: entities grouping
modbus:
  - type: tcp
    host: IP_ADDRESS_1
    port: 2020
    name: "modbus_hub"
    binary_sensors:
      - name: binary_sensor1
        address: 100
    climates:
      - name: "Watlow F4T"
        address: 200
    covers:
      - name: Door1
        address: 300
    fans:
      - name: Fan1
        address: 400
    lights:
      - name: light1
        address: 500
    sensors:
      - name: sensor1
        address: 600
    switches:
      - name: Switch1
        address: 700

The different types of entities are detailed in the following.

Configuring binary sensor entities

The Modbus binary sensor allows you to gather data from coils which as per standard have state ON/OFF.

Normally, a register contains 16 coils, giving different addresses depending on the request used.

Register 512: Coil 1 - 16
Register 513: Coil 17 - 32

input_type: coils would use addresses from 1 through 32, while input_type: input would use addresses 512 and 513. For that reason, many devices (especially older ones) do not share the coil address space with the register address space, and this input would read from a different address space than coil. The problem is present in devices with shared address space and are a frequent cause of problems when configuring entities.

Please refer to Parameter usage for conflicting parameters.

Configuration Variables

binary_sensors map (Optional)

A list of all binary sensors configured for this connection.

device_class string (Optional)

The type/class to be used for the UI.

input_type string (Optional, default: coil)

Type of request discrete_input, coil, holding or input

slave_count integer (Optional)

Identical to virtual_count.

virtual_count integer (Optional)

Generate count+1 binary sensors (master + slaves). Addresses are automatically incremented. The parameter simplifies configuration and provides a much better performance by not using count+1 requests but a single request.

unique_id string (Optional)

ID that uniquely identifies the entity. Slaves will automatically be given a unique_id of <<unique_id>>_<<slave_index>>. If two sensors have the same unique ID, Home Assistant will raise an exception.

Example: typical binary sensor configuration

# Example yaml: typical binary_sensor
modbus:
  - name: hub1
    type: tcp
    host: IP_ADDRESS
    port: 502
    binary_sensors:
      - name: my_relay
        address: 100
        slave: 1

Example: full binary sensor configuration

# Example yaml: binary_sensor with all options
modbus:
  - name: hub1
    type: tcp
    host: IP_ADDRESS
    port: 502
    binary_sensors:
      - name: my_relay
        address: 100
        device_class: door
        input_type: coil
        scan_interval: 15
        slave: 1
        slave_count: 0
        unique_id: my_relay

Example: multiple identical binary sensor configuration

# Example of 10 identical binary_sensor
modbus:
  - name: hub1
    type: tcp
    host: IP_ADDRESS
    port: 502
    binary_sensors:
      - name: my_relay
        address: 100
        slave: 1
        slave_count: 10
        unique_id: my_relay

This configuration will poll coil addresses 100 to 110 every 15 seconds and update the binary_sensors: my_relay and my_relay_1 to my_relay_10.

The master configuration like device_class are automatically copied to the slaves.

Configuring climate entities

The Modbus climate platform allows you to monitor a thermostat or heaters as well as set a target temperature, HVAC mode and fan state.

Please refer to Parameter usage for conflicting parameters.

Configuration Variables

climates map (Optional)

A list of all climate entities in this modbus instance.

count integer (Optional)

Number of registers to read. only valid for data_type: custom and data_type: string, for other data types count is automatically calculated.

data_type list (Optional, default: int16)

Response representation.

custom

user defined format, structure: and count: must be configured.

float16

16 bit signed float (1 register holds 1 value).

float32

32 bit signed float (2 registers holds 1 value).

float64

64 bit signed float (4 register holds 1 value).

int

DEPRECATED is silently converted to int16

int16

16 bit signed integer (1 register holds 1 value).

int32

32 bit signed integer (2 registers holds 1 value).

int64

64 bit signed integer (4 registers holds 1 value).

string

set of 8 bit characters, count: must be configured.

uint

DEPRECATED is silently converted to uint16

uint16

16 bit unsigned integer (1 register holds 1 value).

uint32

32 bit unsigned integer (2 registers holds 1 value).

uint64

64 bit unsigned integer (4 registers holds 1 value).

hvac_mode_register map (Optional)

Configuration of register for HVAC mode

address integer Required

Address of HVAC mode register.

write_registers boolean (Optional, default: false)

Request type, use write_registers if true else write_register. If more than one value is specified for a specific mode, only the first one is used for writing to the register.

values map Required

Mapping between the register values and HVAC modes

state_off integer | list (Optional)

Value corresponding to HVAC Off mode.

state_heat integer | list (Optional)

Value corresponding to HVAC Heat mode.

state_cool integer | list (Optional)

Value corresponding to HVAC Cool mode.

state_auto integer | list (Optional)

Value corresponding to HVAC Auto mode.

state_dry integer | list (Optional)

Value corresponding to HVAC Dry mode.

state_fan_only integer | list (Optional)

Value corresponding to HVAC Fan only mode.

state_heat_cool integer | list (Optional)

Value corresponding to HVAC Heat/Cool mode.

fan_mode_register map (Optional)

Configuration of register for Fan mode

address integer | list Required

Address of Fan mode register. (int to call write_register, list of 1 int to call write_registers)

values map Required

Mapping between the register values and Fan modes This is typically used to control one of: Speed, Direction or On/Off state.

state_fan_on integer (Optional)

Value corresponding to Fan On mode.

state_fan_off integer (Optional)

Value corresponding to Fan Off mode.

state_fan_low integer (Optional)

Value corresponding to Fan Low mode.

state_fan_medium integer (Optional)

Value corresponding to Fan Medium mode.

state_fan_high integer (Optional)

Value corresponding to Fan High mode.

state_fan_auto integer (Optional)

Value corresponding to Fan Auto mode.

state_fan_top integer (Optional)

Value corresponding to Fan Top mode.

state_fan_middle integer (Optional)

Value corresponding to Fan Middle mode.

state_fan_focus integer (Optional)

Value corresponding to Fan Focus mode.

state_fan_diffuse integer (Optional)

Value corresponding to Fan Diffuse mode.

hvac_onoff_register integer (Optional)

Address of On/Off state. When zero is read from this register, the HVAC state is set to Off, otherwise the hvac_mode_register dictates the state of the HVAC. If no such register is defined, it defaults to Auto. When the HVAC mode is set to Off, the value 0 is written to the register, otherwise the value 1 is written.

swing_mode_register map (Optional)

Configuration of the register for swing mode

address integer | list Required

Address of swing mode register. (int to call write_register, list of 1 int to call write_registers). - Reading done through holding register

values map Required

Mapping between the register values and swing modes

swing_mode_state_on integer (Optional)

Value corresponding to swing mode on.

swing_mode_state_off integer (Optional)

Value corresponding to swing mode off.

swing_mode_state_horizontal integer (Optional)

Value corresponding to swing mode horizontal.

swing_mode_state_vertical integer (Optional)

Value corresponding to swing mode vertical.

swing_mode_state_both integer (Optional)

Value corresponding to Swing mode both.

input_type list (Optional, default: holding)

Modbus register type for current temperature.

holding

Holding register.

input

Input register.

max_temp integer (Optional, default: 35)

Maximum setpoint temperature.

min_temp integer (Optional, default: 5)

Minimum setpoint temperature.

offset float (Optional, default: 0)

Final offset (output = scale * value + offset).

precision integer (Optional, default: 0)

Number of valid decimals.

scale float (Optional, default: 1)

Scale factor (output = scale * value + offset).

structure string (Optional)

If data_type: custom is specified a double-quoted Python struct is expected, to format the string to unpack the value. See Python documentation for details. Example: >i.

Default:

f

swap list (Optional, default: none)

Swap the order of bytes/words, not valid with custom and datatype: string

byte

Swap bytes AB -> BA.

word

Swap word ABCD -> CDAB, not valid with data types: int16, uint16

word_byte

Swap word ABCD -> DCBA, not valid with data types: int16, uint16

target_temp_register integer | list Required

Register address for target temperature (Setpoint). Using a list, it is possible to define one register for each of the available HVAC Modes. The list has to have a fixed size of 7 registers corresponding to the 7 available HVAC Modes, as follows: Register 1: HVAC AUTO mode; Register 2: HVAC Cool mode; Register 3: HVAC Dry mode; Register 4: HVAC Fan only mode; Register 5: HVAC Heat mode; Register 6: HVAC Heat Cool mode; Register 7: HVAC OFF mode. It is possible to set duplicated values for the modes where the devices has not a related register.

target_temp_write_registers boolean (Optional, default: false)

If true use write_registers for target temperature.

temp_step float (Optional, default: 0.5)

Step size target temperature.

temperature_unit list (Optional, default: C)

Temperature unit reported by current_temp_register. C or F.

C

Celsius

F

Fahrenheit

write_registers boolean (Optional, default: false)

Request type, use write_registers if true else write_register.

Example: climate configuration

# Example configuration.yaml entry
modbus:
  - name: hub1
    type: tcp
    host: IP_ADDRESS
    port: 502
    climates:
      - name: "Watlow F4T"
        address: 27586
        input_type: holding
        count: 1
        data_type: custom
        max_temp: 35
        min_temp: 15
        offset: 0
        precision: 1
        scale: 0.1
        max_temp: 30
        structure: ">f"
        target_temp_register: 2782
        target_temp_write_registers: true
        temp_step: 1
        temperature_unit: C

Configuring cover entities

The modbus cover platform allows you to control covers (such as blinds, a roller shutter, or a garage door).

At the moment, platform cover support the opening and closing of a cover. You can control your covers either using coils or holding registers.

Cover that uses input_type: coil is not able to determine intermediary states such as opening and closing. Coil stores only two states — “0” means cover closed, and “1” implies cover open. To allow detecting intermediary states, there is an optional status_register attribute. It will enable you to write your command (e.g., to open a cover) into a coil, and read current cover status back through the register. Additionally, you can specify values for state_open, state_opening, state_closed, and state_closing attributes. These will be matched with the value read from the status_register.

If your cover uses input_type: holding (default) to send commands, it can also read the intermediary states. To adjust which value represents what state, you can fine-tune the optional state attributes, like state_open. These optional state values are also used for specifying values written into the register. If you specify an optional status_register attribute, cover states will be read from status_register instead of the register used for sending commands.

Please refer to Parameter usage for conflicting parameters.

Configuration Variables

covers map Required

A list of all cover entities configured for this connection.

device_class device_class (Optional, default: None)

The type/class of the cover to set the icon in the frontend.

input_type list (Optional, default: holding)

Cover register type.

holding

Holding register.

input

Input register.

state_open integer (Optional, default: 1)

A value in status_register or register representing an open cover. If your configuration uses the register attribute, this value will be written into the holding register to open the cover.

state_closed integer (Optional, default: 0)

A value in status_register or register representing a closed cover. If your configuration uses the register attribute, this value will be written into the holding register to close the cover.

state_opening integer (Optional, default: 2)

A value in status_register or register representing an opening cover. Note that this state should be also supported on your connected Modbus cover. If it won’t report the state, this state won’t be detected.

state_closing integer (Optional, default: 3)

A value in status_register or register representing a closing cover. Note that this state should be also supported on your connected Modbus cover. If it will not report the state, this state won’t be detected.

status_register integer (Optional)

Address of register, from which all the cover states will be read. If you specified register attribute, and not status_register attribute, your main register will also be used as a status register.

status_register_type list (Optional)

Cover status register type (holding, input), default holding.

holding

Holding register.

input

Input register.

Example: Modbus cover

# Example configuration.yaml entry
modbus:
  - name: hub1
    type: tcp
    host: IP_ADDRESS
    port: 502
    covers:
      - name: Door1
        device_class: door
        input_type: coil
        address: 117
        state_open: 1
        state_opening: 2
        state_closed: 0
        state_closing: 3
        status_register: 119
        status_register_type: holding
      - name: "Door2"
        address: 118

Example: Modbus cover controlled by a coil

This example shows a configuration for a Modbus cover controlled using a coil. Intermediary states like opening/closing are not supported. The cover state is polled from Modbus every 10 seconds.

modbus:
  - name: hub1
    type: tcp
    host: IP_ADDRESS
    port: 502
    covers:
      - name: Door1
        slave: 1
        coil: 1
        device_class: door
        scan_interval: 10
      - name: Door2
        slave: 2
        coil: 2
        device_class: door
        scan_interval: 10

Example: Modbus cover controlled by a coil, its state is read from the register

This example shows a configuration for a Modbus cover controlled using a coil. Actual cover state is read from the status_register. We’ve also specified register values to match with the states open/opening/closed/closing. The cover state is polled from Modbus every 10 seconds.

modbus:
  - name: hub1
    type: tcp
    host: IP_ADDRESS
    port: 502
    covers:
      - name: Door1
        slave: 1
        device_class: door
        scan_interval: 10
        coil: 1
        status_register: 1
        status_register_type: input
        state_opening: 1
        state_open: 2
        state_closing: 3
        state_closed: 4

Example: Modbus cover controlled by a holding register

This example shows a configuration for a Modbus cover controlled using a holding register, from which we also read current cover state. We’ve also specified register values to match with the states open/opening/closed/closing. The cover state is polled from Modbus every 10 seconds.

modbus:
  - name: hub1
    type: tcp
    host: IP_ADDRESS
    port: 502
    covers:
      - name: Door1
        slave: 1
        device_class: door
        scan_interval: 10
        register: 1
        state_opening: 1
        state_open: 2
        state_closing: 3
        state_closed: 4

Example: Modbus cover controlled by a holding register, its state is read from the status register

This example shows a configuration for a Modbus cover controlled using a holding register. However, cover state is read from a status_register. In this case, we’ve specified only values for state_open and state_closed, for the rest, default values are used. The cover state is polled from Modbus every 10 seconds.

modbus:
  - name: hub1
    type: tcp
    host: IP_ADDRESS
    port: 502

    covers:
      - name: Door1
        slave: 1
        device_class: door
        scan_interval: 10
        register: 1
        status_register: 2
        register_type: holding
        state_open: 1
        state_closed: 0

Configuring fan entities

The modbus fan platform allows you to control Modbus coils or registers.

Please refer to Parameter usage for conflicting parameters.

Configuration Variables

fans map Required

A list of all fan entities in this modbus instance.

command_on integer (Optional, default: 1)

Value to write to turn on the fan.

command_off integer (Optional, default: 0)

Value to write to turn off the fan.

write_type list (Optional, default: holding)

Type of write request.

holding

write_register is called.

holdings

write_registers is called.

coil

write_coil is called.

coils

write_coils is called.

verify map (Optional)

Read from Modbus device to verify fan. If used without attributes, it uses the toggle register configuration. If omitted, no verification is done, but the state of the fan is set with each toggle.

address integer (Optional, default: write address)

Address to read from.

delay integer (Optional, default: 0)

Delay between write and verify.

input_type list (Optional)

Type of address.

Default:

same as write_type

coil

Coil (1bit relay).

discrete

Discret input (1bit relay).

holding

Holding register.

input

Input register.

state_on integer (Optional)

Value when the fan is on.

Default:

same as command_on

state_off integer (Optional)

Value when the fan is off.

Default:

same as command_off

Example: fan configuration

# Example configuration.yaml entry
modbus:
  - type: tcp
    host: IP_ADDRESS
    port: 502
    fans:
      - name: "Fan1"
        address: 13
        write_type: coil
      - name: "Fan2"
        slave: 2
        address: 14
        write_type: coil
        verify:
      - name: "Register1"
        address: 11
        command_on: 1
        command_off: 0
        verify:
            input_type: holding
            address: 127
            state_on: 25
            state_off: 1

Configuring light entities

The modbus light platform allows you to control Modbus coils or registers.

Please refer to Parameter usage for conflicting parameters.

Configuration Variables

lights map Required

A list of all light entities in this modbus instance.

command_on integer (Optional, default: 1)

Value to write to turn on the light.

command_off integer (Optional, default: 0)

Value to write to turn off the light.

write_type list (Optional, default: holding)

Type of write request.

holding

write_register is called.

holdings

write_registers is called.

coil

write_coil is called.

coils

write_coils is called.

verify map (Optional)

Read from Modbus device to verify the light. If used without attributes, it uses the toggle register configuration. If omitted no verification, is done, but the state of the light is set with each toggle.

address integer (Optional)

Address to read from.

Default:

Same as address

delay integer (Optional, default: 0)

delay between write and verify.

input_type list (Optional)

Type of address (holding/coil/discrete/input).

Default:

Same as write_type

coil

Coil (1bit relay).

discrete

Discrete inout (1bit relay).

holding

Holding register.

input

Input register.

state_on integer (Optional)

Value when the light is on.

Default:

Same as command_on

state_off integer (Optional)

Value when the light is off.

Default:

Same as command_off

Example: light configuration

# Example configuration.yaml entry
modbus:
  - type: tcp
    host: IP_ADDRESS
    port: 502
    lights:
      - name: "light1"
        address: 13
        write_type: coil
      - name: "light2"
        slave: 2
        address: 14
        write_type: coil
        verify:
      - name: "Register1"
        address: 11
        command_on: 1
        command_off: 0
        verify:
            input_type: holding
            address: 127
            state_on: 25
            state_off: 1

Configuring sensor entities

The modbus sensor allows you to gather data from Modbus registers.

Please refer to Parameter usage for conflicting parameters.

Configuration Variables

sensors map Required

A list of all sensors in this modbus instance.

count integer (Optional)

Number of registers to read. only valid for data_type: custom and data_type: string, for other data types count is automatically calculated.

data_type list (Optional, default: int16)

Response representation.

custom

user defined format, structure: and count: must be configured.

float16

16 bit signed float (1 register holds 1 value).

float32

32 bit signed float (2 registers holds 1 value).

float64

64 bit signed float (4 register holds 1 value).

int

DEPRECATED is silently converted to int16

int16

16 bit signed integer (1 register holds 1 value).

int32

32 bit signed integer (2 registers holds 1 value).

int64

64 bit signed integer (4 registers holds 1 value).

string

set of 8 bit characters, count: must be configured.

uint

DEPRECATED is silently converted to uint16

uint16

16 bit unsigned integer (1 register holds 1 value).

uint32

32 bit unsigned integer (2 registers holds 1 value).

uint64

64 bit unsigned integer (4 registers holds 1 value).

device_class device_class (Optional, default: None)

The type/class of the sensor to set the icon in the frontend.

input_type list (Optional, default: holding)

Modbus register type for sensor.

holding

Holding register.

input

Input register.

min_value float (Optional)

The minimum allowed value of a sensor. If value < min_value –> min_value. Can be float or integer

max_value float (Optional)

The maximum allowed value of a sensor. If value > max_value –> max_value. Can be float or integer

nan_value string (Optional)

If a Modbus sensor has a defined NaN value, this value can be set as a hex string starting with 0x containing one or more bytes (for example, 0xFFFF or 0x80000000) or provided as an integer directly. If triggered, the sensor becomes unavailable. Please note that the hex to int conversion for nan_value does currently not obey home-assistants Modbus encoding using the data_type, structure, or swap arguments.

zero_suppress float (Optional)

Suppress values close to zero. If -zero_suppress <= value <= +zero_suppress –> 0. Can be float or integer

offset float (Optional, default: 0)

Final offset (output = scale * value + offset).

precision integer (Optional, default: 0)

Number of valid decimals.

scale float (Optional, default: 1)

Scale factor (output = scale * value + offset).

slave_count integer (Optional)

Identical to virtual_count.

virtual_count integer (Optional)

Generates x-1 slave sensors, allowing read of multiple registers with a single read message.

state_class string (Optional)

The state_class of the sensor.

structure string (Optional)

If data_type: custom is specified a double-quoted Python struct is expected, to format the string to unpack the value. See Python documentation for details. Example: >i.

Default:

f

swap list (Optional, default: none)

Swap the order of bytes/words, not valid with custom and datatype: string

byte

Swap bytes AB -> BA.

word

Swap word ABCD -> CDAB, not valid with data types: int16, uint16

word_byte

Swap word ABCD -> DCBA, not valid with data types: int16, uint16

unit_of_measurement string (Optional)

Unit to attach to value.

unique_id string (Optional)

ID that uniquely identifies the entity. If two sensors have the same unique ID, Home Assistant will raise an exception.

If you specify scale or offset as floating point values, double precision floating point arithmetic will be used to calculate final value. This can cause loss of precision for values that are larger than 2^53.

Example: sensor configuration

# Example configuration.yaml entry
modbus:
  - name: hub1
    type: tcp
    host: IP_ADDRESS
    port: 502
    sensors:
      - name: Sensor1
        unit_of_measurement: °C
        slave: 1
        address: 100
      - name: Sensor2
        unit_of_measurement: mg
        address: 110
        count: 2
      - name: Sensor3
        unit_of_measurement: °C
        slave: 1
        address: 120
        input_type: input
        data_type: float
        scale: 0.01
        offset: -273.16
        precision: 2

Example: sensor full configuration

Example temperature sensor with a default scan interval:

modbus:
  - name: hub1
    type: tcp
    host: IP_ADDRESS
    port: 502
    sensors:
      - name: Room_1
        slave: 10
        address: 0
        input_type: holding
        unit_of_measurement: °C
        state_class: measurement
        count: 1
        scale: 0.1
        offset: 0
        precision: 1
        data_type: integer

Configuring switch entities

The modbus switch platform allows you to control Modbus coils or registers.

Please refer to Parameter usage for conflicting parameters.

Configuration Variables

switches map Required

A list of all switches in this modbus instance.

command_on integer (Optional, default: 1)

Value to write to turn on the switch.

command_off integer (Optional, default: 0)

Value to write to turn off the switch.

write_type list (Optional, default: holding)

Type of write request.

holding

write_register is called.

holdings

write_registers is called.

coil

write_coil is called.

coils

write_coils is called.

verify map (Optional)

Read from Modbus device to verify fan. If used without attributes, it uses the toggle register configuration. If omitted, no verification is done, but the state of the fan is set with each toggle.

address integer (Optional)

Address to read from.

Default:

Same as write address

delay integer (Optional, default: 0)

Delay between write and verify.

input_type list (Optional)

Type of address.

Default:

same as write_type

coil

Coil (1bit relay).

discrete

Discret input (1bit relay).

holding

Holding register.

input

Input register.

state_on integer (Optional)

Value when switch is on.

Default:

Same as command_on

state_off integer (Optional)

Value when switch is off.

Default:

Same as command_off

### Example: switch configuration

# Example configuration.yaml entry
modbus:
  - type: tcp
    host: IP_ADDRESS
    port: 502
    switches:
      - name: Switch1
        address: 13
        write_type: coil
      - name: Switch2
        slave: 2
        address: 14
        write_type: coil
        verify:
      - name: Register1
        address: 11
        command_on: 1
        command_off: 0
        verify:
            input_type: holding
            address: 127
            state_on: 25
            state_off: 1

### Example: switch full configuration

# Example configuration.yaml entry
modbus:
  - type: tcp
    host: IP_ADDRESS
    port: 502
    switches:
      - name: Switch1
        address: 13
        write_type: coil
      - name: Switch2
        slave: 2
        address: 14
        write_type: coil
        verify:
      - name: Register1
        address: 11
        command_on: 1
        command_off: 0
        verify:
            input_type: holding
            address: 127
            state_on: 25
            state_off: 1

Parameters usage matrix

Some parameters exclude other parameters, the following tables show what can be combined:

Datatype: custom string *16 *32 *64
count Yes Yes No No No
structure Yes No No No No
slave_count No No Yes Yes Yes
virtual_count No No Yes Yes Yes
swap: byte No No Yes Yes Yes
swap: word No No No Yes Yes
swap: word_byte No No No Yes Yes

modbus services

The modbus integration provides two generic write services in addition to the platform-specific services.

Service Description
modbus.write_register Write register or registers
modbus.write_coil Write coil or coils

Description:

Attribute Description
hub Hub name (defaults to ‘modbus_hub’ when omitted)
slave Slave address (0-255)
address Address of the Register (e.g. 138)
value (write_register) A single value or an array of 16-bit values. Single value will call modbus function code 0x06. Array will call modbus function code 0x10. Values might need reverse ordering. E.g., to set 0x0004 you might need to set [4,0], this depend on the byte order of your CPU
state (write_coil) A single boolean or an array of booleans. Single boolean will call modbus function code 0x05. Array will call modbus function code 0x0F

The modbus integration also provides communication stop/restart services. These services will not do any reconfiguring, but simply stop/start the modbus communication layer.

Service Description
modbus.stop Stop communication
modbus.restart Restart communication (Stop first if running)

Description:

Attribute Description
hub Hub name (defaults to ‘modbus_hub’ when omitted)

Example: writing a float32 type register

To write a float32 datatype register use network format like 10.0 == 0x41200000 (network order float hexadecimal).

service: modbus.write_register
data:
  address: <target register address>
  slave: <target slave address>
  hub: <hub name>
  value: [0x4120, 0x0000]

Service modbus.set-temperature

Service Description
set_temperature Set temperature. Requires value to be passed in, which is the desired target temperature. value should be in the same type as data_type

Service modbus.set_hvac_mode

Service Description
set_hvac_mode Set HVAC mode. Requires value to be passed in, which is the desired mode. value should be a valid HVAC mode. A mapping between the desired state and the value to be written to the HVAC mode register must exist. Calling this service will also set the On/Off register to an appropriate value, if such a register is defined.

Opening an issue

When opening an issue, please add your current configuration (or a scaled down version), with at least:

  • the modbus configuration lines
  • the entity (sensor, etc.) lines

In order for the developers better to identify the problem, please add the following lines to configuration.yamlThe configuration.yaml file is the main configuration file for Home Assistant. It lists the integrations to be loaded and their specific configurations. In some cases, the configuration needs to be edited manually directly in the configuration.yaml file. Most integrations can be configured in the UI.[Learn more]:

logger:
  default: warning
  logs:
    homeassistant.components.modbus: debug
    pymodbus: debug

and restart Home Assistant, reproduce the problem, and include the log in the issue.

Building on top of modbus

The only recommended way is to inherit the entities needed.