Modbus - Air Quality Bricklet

This is the description of the Modbus protocol for the Air Quality Bricklet. General information and technical specifications for the Air Quality Bricklet are summarized in its hardware description.

API

A general description of the Modbus protocol structure can be found here.

Basic Functions

BrickletAirQuality.get_all_values
Function ID:
  • 1
Request:
  • empty payload
Response:
  • iaq_index – Type: int32, Range: [0 to 500]
  • iaq_index_accuracy – Type: uint8, Range: See meanings
  • temperature – Type: int32, Unit: 1/100 °C, Range: [-231 to 231 - 1]
  • humidity – Type: int32, Unit: 1/100 %, Range: [-231 to 231 - 1]
  • air_pressure – Type: int32, Unit: 1/100 hPa, Range: [-231 to 231 - 1]

Returns all values measured by the Air Quality Bricklet. The values are IAQ (Indoor Air Quality) Index (higher value means greater level of air pollution), IAQ Index Accuracy, Temperature, Humidity and Air Pressure.

Air Quality Index description

The following meanings are defined for the elements of this function:

For iaq_index_accuracy:

  • 0 = Unreliable
  • 1 = Low
  • 2 = Medium
  • 3 = High
BrickletAirQuality.set_temperature_offset
Function ID:
  • 2
Request:
  • offset – Type: int32, Unit: 1/100 °C, Range: [-231 to 231 - 1]
Response:
  • no response

Sets a temperature offset. A offset of 10 will decrease the measured temperature by 0.1 °C.

If you install this Bricklet into an enclosure and you want to measure the ambient temperature, you may have to decrease the measured temperature by some value to compensate for the error because of the heating inside of the enclosure.

We recommend that you leave the parts in the enclosure running for at least 24 hours such that a temperature equilibrium can be reached. After that you can measure the temperature directly outside of enclosure and set the difference as offset.

This temperature offset is used to calculate the relative humidity and IAQ index measurements. In case the Bricklet is installed in an enclosure, we recommend to measure and set the temperature offset to improve the accuracy of the measurements.

BrickletAirQuality.get_temperature_offset
Function ID:
  • 3
Request:
  • empty payload
Response:
  • offset – Type: int32, Unit: 1/100 °C, Range: [-231 to 231 - 1]

Returns the temperature offset as set by set_temperature_offset.

BrickletAirQuality.get_iaq_index
Function ID:
  • 7
Request:
  • empty payload
Response:
  • iaq_index – Type: int32, Range: [0 to 500]
  • iaq_index_accuracy – Type: uint8, Range: See meanings

Returns the IAQ index and accuracy. The higher the IAQ index, the greater the level of air pollution.

IAQ index description

If you want to get the value periodically, it is recommended to use the CALLBACK_IAQ_INDEX callback. You can set the callback configuration with set_iaq_index_callback_configuration.

The following meanings are defined for the elements of this function:

For iaq_index_accuracy:

  • 0 = Unreliable
  • 1 = Low
  • 2 = Medium
  • 3 = High
BrickletAirQuality.get_temperature
Function ID:
  • 11
Request:
  • empty payload
Response:
  • temperature – Type: int32, Unit: 1/100 °C, Range: [-231 to 231 - 1]

Returns temperature.

If you want to get the value periodically, it is recommended to use the CALLBACK_TEMPERATURE callback. You can set the callback configuration with set_temperature_callback_configuration.

BrickletAirQuality.get_humidity
Function ID:
  • 15
Request:
  • empty payload
Response:
  • humidity – Type: int32, Unit: 1/100 %, Range: [-231 to 231 - 1]

Returns relative humidity.

If you want to get the value periodically, it is recommended to use the CALLBACK_HUMIDITY callback. You can set the callback configuration with set_humidity_callback_configuration.

BrickletAirQuality.get_air_pressure
Function ID:
  • 19
Request:
  • empty payload
Response:
  • air_pressure – Type: int32, Unit: 1/100 hPa, Range: [-231 to 231 - 1]

Returns air pressure.

If you want to get the value periodically, it is recommended to use the CALLBACK_AIR_PRESSURE callback. You can set the callback configuration with set_air_pressure_callback_configuration.

Advanced Functions

BrickletAirQuality.remove_calibration
Function ID:
  • 23
Request:
  • empty payload
Response:
  • no response

Deletes the calibration from flash. After you call this function, you need to power cycle the Air Quality Bricklet.

On the next power up the Bricklet will start a new calibration, as if it was started for the very first time.

The calibration is based on the data of the last four days, so it takes four days until a full calibration is re-established.

New in version 2.0.3 (Plugin).

BrickletAirQuality.set_background_calibration_duration
Function ID:
  • 24
Request:
  • duration – Type: uint8, Range: See meanings, Default: 1
Response:
  • no response

The Air Quality Bricklet uses an automatic background calibration mechanism to calculate the IAQ Index. This calibration mechanism considers a history of measured data. The duration of this history can be configured to either be 4 days or 28 days.

If you keep the Bricklet mostly at one place and it does not get moved around to different environments, we recommend that you use a duration of 28 days.

If you change the duration, the current calibration will be discarded and the calibration will start from beginning again. The configuration of the duration is saved in flash, so you should only have to call this function once in the lifetime of the Bricklet.

The Bricklet has to be power cycled after this function is called for a duration change to take effect.

Before firmware version 2.0.3 this was not configurable and the duration was 4 days.

The default value (since firmware version 2.0.3) is 28 days.

New in version 2.0.3 (Plugin).

The following meanings are defined for the elements of this function:

For duration:

  • 0 = 4 Days
  • 1 = 28 Days
BrickletAirQuality.get_background_calibration_duration
Function ID:
  • 25
Request:
  • empty payload
Response:
  • duration – Type: uint8, Range: See meanings, Default: 1

Returns the background calibration duration as set by set_background_calibration_duration.

New in version 2.0.3 (Plugin).

The following meanings are defined for the elements of this function:

For duration:

  • 0 = 4 Days
  • 1 = 28 Days
BrickletAirQuality.get_spitfp_error_count
Function ID:
  • 234
Request:
  • empty payload
Response:
  • error_count_ack_checksum – Type: uint32, Range: [0 to 232 - 1]
  • error_count_message_checksum – Type: uint32, Range: [0 to 232 - 1]
  • error_count_frame – Type: uint32, Range: [0 to 232 - 1]
  • error_count_overflow – Type: uint32, Range: [0 to 232 - 1]

Returns the error count for the communication between Brick and Bricklet.

The errors are divided into

  • ACK checksum errors,
  • message checksum errors,
  • framing errors and
  • overflow errors.

The errors counts are for errors that occur on the Bricklet side. All Bricks have a similar function that returns the errors on the Brick side.

BrickletAirQuality.set_status_led_config
Function ID:
  • 239
Request:
  • config – Type: uint8, Range: See meanings, Default: 3
Response:
  • no response

Sets the status LED configuration. By default the LED shows communication traffic between Brick and Bricklet, it flickers once for every 10 received data packets.

You can also turn the LED permanently on/off or show a heartbeat.

If the Bricklet is in bootloader mode, the LED is will show heartbeat by default.

The following meanings are defined for the elements of this function:

For config:

  • 0 = Off
  • 1 = On
  • 2 = Show Heartbeat
  • 3 = Show Status
BrickletAirQuality.get_status_led_config
Function ID:
  • 240
Request:
  • empty payload
Response:
  • config – Type: uint8, Range: See meanings, Default: 3

Returns the configuration as set by set_status_led_config

The following meanings are defined for the elements of this function:

For config:

  • 0 = Off
  • 1 = On
  • 2 = Show Heartbeat
  • 3 = Show Status
BrickletAirQuality.get_chip_temperature
Function ID:
  • 242
Request:
  • empty payload
Response:
  • temperature – Type: int16, Unit: 1 °C, Range: [-215 to 215 - 1]

Returns the temperature as measured inside the microcontroller. The value returned is not the ambient temperature!

The temperature is only proportional to the real temperature and it has bad accuracy. Practically it is only useful as an indicator for temperature changes.

BrickletAirQuality.reset
Function ID:
  • 243
Request:
  • empty payload
Response:
  • no response

Calling this function will reset the Bricklet. All configurations will be lost.

After a reset you have to create new device objects, calling functions on the existing ones will result in undefined behavior!

BrickletAirQuality.get_identity
Function ID:
  • 255
Request:
  • empty payload
Response:
  • uid – Type: char[8]
  • connected_uid – Type: char[8]
  • position – Type: char, Range: ['a' to 'h', 'z']
  • hardware_version – Type: uint8[3]
    • 0: major – Type: uint8, Range: [0 to 255]
    • 1: minor – Type: uint8, Range: [0 to 255]
    • 2: revision – Type: uint8, Range: [0 to 255]
  • firmware_version – Type: uint8[3]
    • 0: major – Type: uint8, Range: [0 to 255]
    • 1: minor – Type: uint8, Range: [0 to 255]
    • 2: revision – Type: uint8, Range: [0 to 255]
  • device_identifier – Type: uint16, Range: [0 to 216 - 1]

Returns the UID, the UID where the Bricklet is connected to, the position, the hardware and firmware version as well as the device identifier.

The position can be 'a', 'b', 'c', 'd', 'e', 'f', 'g' or 'h' (Bricklet Port). A Bricklet connected to an Isolator Bricklet is always at position 'z'.

The device identifier numbers can be found here

Callback Configuration Functions

BrickletAirQuality.set_all_values_callback_configuration
Function ID:
  • 4
Request:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
Response:
  • no response

The period is the period with which the CALLBACK_ALL_VALUES callback is triggered periodically. A value of 0 turns the callback off.

If the value has to change-parameter is set to true, the callback is only triggered after at least one of the values has changed. If the values didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

BrickletAirQuality.get_all_values_callback_configuration
Function ID:
  • 5
Request:
  • empty payload
Response:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false

Returns the callback configuration as set by set_all_values_callback_configuration.

BrickletAirQuality.set_iaq_index_callback_configuration
Function ID:
  • 8
Request:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
Response:
  • no response

The period is the period with which the CALLBACK_IAQ_INDEX callback is triggered periodically. A value of 0 turns the callback off.

If the value has to change-parameter is set to true, the callback is only triggered after at least one of the values has changed. If the values didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

BrickletAirQuality.get_iaq_index_callback_configuration
Function ID:
  • 9
Request:
  • empty payload
Response:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false

Returns the callback configuration as set by set_iaq_index_callback_configuration.

BrickletAirQuality.set_temperature_callback_configuration
Function ID:
  • 12
Request:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
  • option – Type: char, Range: See meanings, Default: 'x'
  • min – Type: int32, Unit: 1/100 °C, Range: [-231 to 231 - 1], Default: 0
  • max – Type: int32, Unit: 1/100 °C, Range: [-231 to 231 - 1], Default: 0
Response:
  • no response

The period is the period with which the CALLBACK_TEMPERATURE callback is triggered periodically. A value of 0 turns the callback off.

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the CALLBACK_TEMPERATURE callback.

The following options are possible:

Option Description
'x' Threshold is turned off
'o' Threshold is triggered when the value is outside the min and max values
'i' Threshold is triggered when the value is inside or equal to the min and max values
'<' Threshold is triggered when the value is smaller than the min value (max is ignored)
'>' Threshold is triggered when the value is greater than the min value (max is ignored)

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

The following meanings are defined for the elements of this function:

For option:

  • 'x' = Off
  • 'o' = Outside
  • 'i' = Inside
  • '<' = Smaller
  • '>' = Greater
BrickletAirQuality.get_temperature_callback_configuration
Function ID:
  • 13
Request:
  • empty payload
Response:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
  • option – Type: char, Range: See meanings, Default: 'x'
  • min – Type: int32, Unit: 1/100 °C, Range: [-231 to 231 - 1], Default: 0
  • max – Type: int32, Unit: 1/100 °C, Range: [-231 to 231 - 1], Default: 0

Returns the callback configuration as set by set_temperature_callback_configuration.

The following meanings are defined for the elements of this function:

For option:

  • 'x' = Off
  • 'o' = Outside
  • 'i' = Inside
  • '<' = Smaller
  • '>' = Greater
BrickletAirQuality.set_humidity_callback_configuration
Function ID:
  • 16
Request:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
  • option – Type: char, Range: See meanings, Default: 'x'
  • min – Type: int32, Unit: 1/100 %, Range: [-231 to 231 - 1], Default: 0
  • max – Type: int32, Unit: 1/100 %, Range: [-231 to 231 - 1], Default: 0
Response:
  • no response

The period is the period with which the CALLBACK_HUMIDITY callback is triggered periodically. A value of 0 turns the callback off.

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the CALLBACK_HUMIDITY callback.

The following options are possible:

Option Description
'x' Threshold is turned off
'o' Threshold is triggered when the value is outside the min and max values
'i' Threshold is triggered when the value is inside or equal to the min and max values
'<' Threshold is triggered when the value is smaller than the min value (max is ignored)
'>' Threshold is triggered when the value is greater than the min value (max is ignored)

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

The following meanings are defined for the elements of this function:

For option:

  • 'x' = Off
  • 'o' = Outside
  • 'i' = Inside
  • '<' = Smaller
  • '>' = Greater
BrickletAirQuality.get_humidity_callback_configuration
Function ID:
  • 17
Request:
  • empty payload
Response:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
  • option – Type: char, Range: See meanings, Default: 'x'
  • min – Type: int32, Unit: 1/100 %, Range: [-231 to 231 - 1], Default: 0
  • max – Type: int32, Unit: 1/100 %, Range: [-231 to 231 - 1], Default: 0

Returns the callback configuration as set by set_humidity_callback_configuration.

The following meanings are defined for the elements of this function:

For option:

  • 'x' = Off
  • 'o' = Outside
  • 'i' = Inside
  • '<' = Smaller
  • '>' = Greater
BrickletAirQuality.set_air_pressure_callback_configuration
Function ID:
  • 20
Request:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
  • option – Type: char, Range: See meanings, Default: 'x'
  • min – Type: int32, Unit: 1/100 hPa, Range: [-231 to 231 - 1], Default: 0
  • max – Type: int32, Unit: 1/100 hPa, Range: [-231 to 231 - 1], Default: 0
Response:
  • no response

The period is the period with which the CALLBACK_AIR_PRESSURE callback is triggered periodically. A value of 0 turns the callback off.

If the value has to change-parameter is set to true, the callback is only triggered after the value has changed. If the value didn't change within the period, the callback is triggered immediately on change.

If it is set to false, the callback is continuously triggered with the period, independent of the value.

It is furthermore possible to constrain the callback with thresholds.

The option-parameter together with min/max sets a threshold for the CALLBACK_AIR_PRESSURE callback.

The following options are possible:

Option Description
'x' Threshold is turned off
'o' Threshold is triggered when the value is outside the min and max values
'i' Threshold is triggered when the value is inside or equal to the min and max values
'<' Threshold is triggered when the value is smaller than the min value (max is ignored)
'>' Threshold is triggered when the value is greater than the min value (max is ignored)

If the option is set to 'x' (threshold turned off) the callback is triggered with the fixed period.

The following meanings are defined for the elements of this function:

For option:

  • 'x' = Off
  • 'o' = Outside
  • 'i' = Inside
  • '<' = Smaller
  • '>' = Greater
BrickletAirQuality.get_air_pressure_callback_configuration
Function ID:
  • 21
Request:
  • empty payload
Response:
  • period – Type: uint32, Unit: 1 ms, Range: [0 to 232 - 1], Default: 0
  • value_has_to_change – Type: bool, Default: false
  • option – Type: char, Range: See meanings, Default: 'x'
  • min – Type: int32, Unit: 1/100 hPa, Range: [-231 to 231 - 1], Default: 0
  • max – Type: int32, Unit: 1/100 hPa, Range: [-231 to 231 - 1], Default: 0

Returns the callback configuration as set by set_air_pressure_callback_configuration.

The following meanings are defined for the elements of this function:

For option:

  • 'x' = Off
  • 'o' = Outside
  • 'i' = Inside
  • '<' = Smaller
  • '>' = Greater

Callbacks

BrickletAirQuality.CALLBACK_ALL_VALUES
Function ID:
  • 6
Response:
  • iaq_index – Type: int32, Range: [0 to 500]
  • iaq_index_accuracy – Type: uint8, Range: See meanings
  • temperature – Type: int32, Unit: 1/100 °C, Range: [-231 to 231 - 1]
  • humidity – Type: int32, Unit: 1/100 %, Range: [-231 to 231 - 1]
  • air_pressure – Type: int32, Unit: 1/100 hPa, Range: [-231 to 231 - 1]

This callback is triggered periodically according to the configuration set by set_all_values_callback_configuration.

The response values are the same as get_all_values.

The following meanings are defined for the elements of this function:

For iaq_index_accuracy:

  • 0 = Unreliable
  • 1 = Low
  • 2 = Medium
  • 3 = High
BrickletAirQuality.CALLBACK_IAQ_INDEX
Function ID:
  • 10
Response:
  • iaq_index – Type: int32, Range: [0 to 500]
  • iaq_index_accuracy – Type: uint8, Range: See meanings

This callback is triggered periodically according to the configuration set by set_iaq_index_callback_configuration.

The response values are the same as get_iaq_index.

The following meanings are defined for the elements of this function:

For iaq_index_accuracy:

  • 0 = Unreliable
  • 1 = Low
  • 2 = Medium
  • 3 = High
BrickletAirQuality.CALLBACK_TEMPERATURE
Function ID:
  • 14
Response:
  • temperature – Type: int32, Unit: 1/100 °C, Range: [-231 to 231 - 1]

This callback is triggered periodically according to the configuration set by set_temperature_callback_configuration.

The response value is the same as get_temperature.

BrickletAirQuality.CALLBACK_HUMIDITY
Function ID:
  • 18
Response:
  • humidity – Type: int32, Unit: 1/100 %, Range: [-231 to 231 - 1]

This callback is triggered periodically according to the configuration set by set_humidity_callback_configuration.

The response value is the same as get_humidity.

BrickletAirQuality.CALLBACK_AIR_PRESSURE
Function ID:
  • 22
Response:
  • air_pressure – Type: int32, Unit: 1/100 hPa, Range: [-231 to 231 - 1]

This callback is triggered periodically according to the configuration set by set_air_pressure_callback_configuration.

The response value is the same as get_air_pressure.

Internal Functions

Internal functions are used for maintenance tasks such as flashing a new firmware of changing the UID of a Bricklet. These task should be performed using Brick Viewer instead of using the internal functions directly.

BrickletAirQuality.set_bootloader_mode
Function ID:
  • 235
Request:
  • mode – Type: uint8, Range: See meanings
Response:
  • status – Type: uint8, Range: See meanings

Sets the bootloader mode and returns the status after the requested mode change was instigated.

You can change from bootloader mode to firmware mode and vice versa. A change from bootloader mode to firmware mode will only take place if the entry function, device identifier and CRC are present and correct.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

The following meanings are defined for the elements of this function:

For mode:

  • 0 = Bootloader
  • 1 = Firmware
  • 2 = Bootloader Wait For Reboot
  • 3 = Firmware Wait For Reboot
  • 4 = Firmware Wait For Erase And Reboot

For status:

  • 0 = OK
  • 1 = Invalid Mode
  • 2 = No Change
  • 3 = Entry Function Not Present
  • 4 = Device Identifier Incorrect
  • 5 = CRC Mismatch
BrickletAirQuality.get_bootloader_mode
Function ID:
  • 236
Request:
  • empty payload
Response:
  • mode – Type: uint8, Range: See meanings

Returns the current bootloader mode, see set_bootloader_mode.

The following meanings are defined for the elements of this function:

For mode:

  • 0 = Bootloader
  • 1 = Firmware
  • 2 = Bootloader Wait For Reboot
  • 3 = Firmware Wait For Reboot
  • 4 = Firmware Wait For Erase And Reboot
BrickletAirQuality.set_write_firmware_pointer
Function ID:
  • 237
Request:
  • pointer – Type: uint32, Unit: 1 B, Range: [0 to 232 - 1]
Response:
  • no response

Sets the firmware pointer for write_firmware. The pointer has to be increased by chunks of size 64. The data is written to flash every 4 chunks (which equals to one page of size 256).

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

BrickletAirQuality.write_firmware
Function ID:
  • 238
Request:
  • data – Type: uint8[64], Range: [0 to 255]
Response:
  • status – Type: uint8, Range: [0 to 255]

Writes 64 Bytes of firmware at the position as written by set_write_firmware_pointer before. The firmware is written to flash every 4 chunks.

You can only write firmware in bootloader mode.

This function is used by Brick Viewer during flashing. It should not be necessary to call it in a normal user program.

BrickletAirQuality.write_uid
Function ID:
  • 248
Request:
  • uid – Type: uint32, Range: [0 to 232 - 1]
Response:
  • no response

Writes a new UID into flash. If you want to set a new UID you have to decode the Base58 encoded UID string into an integer first.

We recommend that you use Brick Viewer to change the UID.

BrickletAirQuality.read_uid
Function ID:
  • 249
Request:
  • empty payload
Response:
  • uid – Type: uint32, Range: [0 to 232 - 1]

Returns the current UID as an integer. Encode as Base58 to get the usual string version.