esphome-docs/components/select/modbus_controller.rst

Modbus Controller Select
========================

.. seo::
    :description: Instructions for setting up Modbus Controller Select(s) with ESPHome.

The ``modbus_controller`` Select platform allows you to create a Select from modbus
registers.

.. code-block:: yaml

    # Example configuration entry
    select:
      - platform: modbus_controller
        name: "Modbus Select Register 1000"
        address: 1000
        value_type: U_WORD
        optionsmap:
          "Zero": 0
          "One": 1
          "Two": 2
          "Three": 3


Configuration variables:
------------------------

- **name** (**Required**, string): The name of the Select.
- **address**: (**Required**, int): The start address of the first or only register 
  of the Select.
- **optionsmap**: (**Required**, Map[str, int]): Provide a mapping from options (str) of 
  this Select to values (int) of the modbus register and vice versa. All options and
  all values have to be unique.
- **value_type**: (*Optional*): The datatype of the modbus data. Defaults to ``U_WORD``.
    - ``U_WORD`` (unsigned 16 bit integer from 1 register = 16bit)
    - ``S_WORD`` (signed 16 bit integer from 1 register = 16bit)
    - ``U_DWORD`` (unsigned 32 bit integer from 2 registers = 32bit)
    - ``S_DWORD`` (signed 32 bit integer from 2 registers = 32bit)
    - ``U_DWORD_R`` (unsigned 32 bit integer from 2 registers low word first)
    - ``S_DWORD_R`` (signed 32 bit integer from 2 registers low word first)
    - ``U_QWORD`` (unsigned 64 bit integer from 4 registers = 64bit)
    - ``S_QWORD`` (unsigned 64 bit integer from 4 registers = 64bit)
    - ``U_QWORD_R`` (unsigned 64 bit integer from 4 registers low word first)
    - ``U_QWORD_R`` (signed 64 bit integer from 4 registers low word first)
- **register_count**: (*Optional*): The number of registers which are used for this Select. Only 
  required for uncommon response encodings or to 
  :ref:`optimize modbus communications<modbus_register_count>`. Overrides the defaults determined 
  by ``value_type``.
- **skip_updates**: (*Optional*, int): By default all sensors of of a modbus_controller are 
  updated together. For data points that don't change very frequently updates can be skipped. A
  value of 5 would only update this sensor range in every 5th update cycle. Defaults to ``0``.
  Note: The modbus_controller merges several registers into groups which are updated together. For
  each group the smallest update cycle is used.
- **force_new_range**: (*Optional*, boolean): If possible sensors with sequential addresses are 
  grouped together and requested in one range. Setting this to ``true`` enforces the start of a new 
  range at that address.
- **id** (*Optional*, :ref:`config-id`): Manually specify the ID used for code generation.
- **lambda** (*Optional*, :ref:`lambda <config-lambda>`): Lambda to be evaluated every update interval
  to get the current option of the select.
- **write_lambda** (*Optional*, :ref:`lambda <config-lambda>`): Lambda to be evaluated on every update
  of the Sensor, before the new value is written to the modbus registers.
- **use_write_multiple**: (*Optional*, boolean): By default the modbus command ``Preset Single Registers``
  (function code 6) is used for setting the holding register if only 1 register is set. If your device only supports *Preset Multiple Registers* (function code 16) set this option to ``true``. Defaults
  to ``false``.
- All other options from :ref:`Select <config-select>`.


Parameters passed into ``lambda``
---------------------------------

- **x** (``int64_t``): The parsed integer value of the modbus data.
- **data** (``const std::vector<uint8_t>&``): vector containing the complete raw modbus response bytes for this 
  sensor. Note: because the response contains data for all registers in the same range you have to 
  use ``data[item->offset]`` to get the first response byte for your sensor.
- **item** (``ModbusSelect*const``):  The sensor object itself.

Possible return values for the lambda:

 - ``return <std::string>;`` The new option for this Select.
 - ``return {};`` Use default mapping (see ``optionsmap``).

.. code-block:: yaml

    # example
    lambda: |-
      ESP_LOGD("Reg1000", "Received value %lld", x);
      ESP_LOGD("Reg1000", "Parsed from bytes 0x%x;0x%x", data[item->offset], data[item->offset + 1]);
      if (x > 3) {
        return std::string("Three");
      }      


Parameters passed into ``write_lambda``
---------------------------------------

- **x** (``const std::string&``): The option value to set for this Select.
- **value** (``int64_t``): The mapping value of ``x`` using ``optionsmap``.
- **payload** (``std::vector<uint16_t>& payload``): Empty vector for the payload. The lamdba can add
  16 bit raw modbus register words which are send to the modbus device.
- **item** (``ModbusSelect*const``):  The sensor object itself.

Possible return values for the lambda:

 - ``return <int64_t>;`` the value which should be written to the configured modbus registers. If there were data written to ``payload`` this value is ignored.
 - ``return {};`` Skip updating the register.

.. code-block:: yaml

    # example
    write_lambda: |-
      ESP_LOGD("Reg1000", "Set option to %s (%lld)", x.c_str(), value);

      // re-use default option value from optionsmap
      if (value == 0) {
        return value;
      }

      // return own option value
      if (x == "One") {
        return 2;
      }

      // write payload
      if (x == "Two") {
        payload.push_back(0x0001);
        return 0; // any value will do
      }

      // ignore update
      return {};      


See Also
--------
- :doc:`/components/modbus_controller`
- :doc:`/components/sensor/modbus_controller`
- :doc:`/components/binary_sensor/modbus_controller`
- :doc:`/components/switch/modbus_controller`
- :doc:`/components/text_sensor/modbus_controller`
- :doc:`/components/output/modbus_controller`
- :ref:`automation`
- https://www.modbustools.com/modbus.html
- :ghedit:`Edit`