Modbus - CO2 Bricklet 2.0

This is the description of the Modbus protocol for the CO2 Bricklet 2.0. General information and technical specifications for the CO2 Bricklet 2.0 are summarized in its hardware description.

API

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

Basic Functions

BrickletCO2V2.get_all_values
Function ID:

1

Request:

empty payload

Response:
  • co2_concentration -- uint16
  • temperature -- int16
  • humidity -- uint16

Returns all values measured by the CO2 Bricklet 2.0. The values are CO2 concentration (in ppm), temperature (in 0.01 °C) and humidity (in 0.01 %RH).

If you want to get the values periodically, it is recommended to use the CALLBACK_ALL_VALUES callback. You can set the callback configuration with set_all_values_callback_configuration.

BrickletCO2V2.set_air_pressure
Function ID:

2

Request:
  • air_pressure -- uint16
Response:

no response

The CO2 concentration (among other things) depends on the ambient air pressure.

To increase the accuracy of the CO2 Bricklet 2.0 you can set the current air pressure. You use the Barometer Bricklet 2.0 or the Air Quality Bricklet to get the current air pressure.

The expected unit of the ambient air pressure value is mbar.

By default air pressure compensation is disabled. Once you set a value it will be used for compensation. You can turn the compensation off again by setting the value to 0.

It is sufficient to update the value every few minutes.

BrickletCO2V2.get_air_pressure
Function ID:

3

Request:

empty payload

Response:
  • air_pressure -- uint16

Returns the ambient air pressure as set by set_air_pressure.

BrickletCO2V2.set_temperature_offset
Function ID:

4

Request:
  • offset -- uint16
Response:

no response

Sets a temperature offset with resolution 1/100°C. 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 CO2 concentration. 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.

It is sufficient to set the temperature offset once. The offset is saved in non-volatile memory and is applied again after a power loss.

BrickletCO2V2.get_temperature_offset
Function ID:

5

Request:

empty payload

Response:
  • offset -- uint16

Returns the temperature offset as set by set_temperature_offset.

BrickletCO2V2.get_co2_concentration
Function ID:

9

Request:

empty payload

Response:
  • co2_concentration -- uint16

Returns CO2 concentration in ppm.

If you want to get the value periodically, it is recommended to use the CALLBACK_CO2_CONCENTRATION callback. You can set the callback configuration with set_co2_concentration_callback_configuration.

BrickletCO2V2.get_temperature
Function ID:

13

Request:

empty payload

Response:
  • temperature -- int16

Returns temperature in steps of 0.01 °C.

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.

BrickletCO2V2.get_humidity
Function ID:

17

Request:

empty payload

Response:
  • humidity -- uint16

Returns relative humidity in steps of 0.01 %RH.

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.

Advanced Functions

BrickletCO2V2.get_spitfp_error_count
Function ID:

234

Request:

empty payload

Response:
  • error_count_ack_checksum -- uint32
  • error_count_message_checksum -- uint32
  • error_count_frame -- uint32
  • error_count_overflow -- uint32

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.

BrickletCO2V2.set_bootloader_mode
Function ID:

235

Request:
  • mode -- uint8
Response:
  • status -- uint8

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 parameters of this function:

  • 0: bootloader, for mode
  • 1: firmware, for mode
  • 2: bootloader wait for reboot, for mode
  • 3: firmware wait for reboot, for mode
  • 4: firmware wait for erase and reboot, for mode
  • 0: ok, for status
  • 1: invalid mode, for status
  • 2: no change, for status
  • 3: entry function not present, for status
  • 4: device identifier incorrect, for status
  • 5: crc mismatch, for status
BrickletCO2V2.get_bootloader_mode
Function ID:

236

Request:

empty payload

Response:
  • mode -- uint8

Returns the current bootloader mode, see set_bootloader_mode.

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

  • 0: bootloader, for mode
  • 1: firmware, for mode
  • 2: bootloader wait for reboot, for mode
  • 3: firmware wait for reboot, for mode
  • 4: firmware wait for erase and reboot, for mode
BrickletCO2V2.set_write_firmware_pointer
Function ID:

237

Request:
  • pointer -- uint32
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.

BrickletCO2V2.write_firmware
Function ID:

238

Request:
  • data -- uint8[64]
Response:
  • status -- uint8

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.

BrickletCO2V2.set_status_led_config
Function ID:

239

Request:
  • config -- uint8
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 parameters of this function:

  • 0: off, for config
  • 1: on, for config
  • 2: show heartbeat, for config
  • 3: show status, for config
BrickletCO2V2.get_status_led_config
Function ID:

240

Request:

empty payload

Response:
  • config -- uint8

Returns the configuration as set by set_status_led_config

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

  • 0: off, for config
  • 1: on, for config
  • 2: show heartbeat, for config
  • 3: show status, for config
BrickletCO2V2.get_chip_temperature
Function ID:

242

Request:

empty payload

Response:
  • temperature -- int16

Returns the temperature in °C 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.

BrickletCO2V2.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!

BrickletCO2V2.write_uid
Function ID:

248

Request:
  • uid -- uint32
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.

BrickletCO2V2.read_uid
Function ID:

249

Request:

empty payload

Response:
  • uid -- uint32

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

BrickletCO2V2.get_identity
Function ID:

255

Request:

empty payload

Response:
  • uid -- char[8]
  • connected_uid -- char[8]
  • position -- char
  • hardware_version -- uint8[3]
  • firmware_version -- uint8[3]
  • device_identifier -- uint16

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' or 'd'.

The device identifier numbers can be found here

Callback Configuration Functions

BrickletCO2V2.set_all_values_callback_configuration
Function ID:

6

Request:
  • period -- uint32
  • value_has_to_change -- bool
Response:

no response

The period in ms 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.

The default value is (0, false).

BrickletCO2V2.get_all_values_callback_configuration
Function ID:

7

Request:

empty payload

Response:
  • period -- uint32
  • value_has_to_change -- bool

Returns the callback configuration as set by set_all_values_callback_configuration.

BrickletCO2V2.set_co2_concentration_callback_configuration
Function ID:

10

Request:
  • period -- uint32
  • value_has_to_change -- bool
  • option -- char
  • min -- uint16
  • max -- uint16
Response:

no response

The period in ms is the period with which the CALLBACK_CO2_CONCENTRATION 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_CO2_CONCENTRATION 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 default value is (0, false, 'x', 0, 0).

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

  • x: off, for option
  • o: outside, for option
  • i: inside, for option
  • <: smaller, for option
  • >: greater, for option
BrickletCO2V2.get_co2_concentration_callback_configuration
Function ID:

11

Request:

empty payload

Response:
  • period -- uint32
  • value_has_to_change -- bool
  • option -- char
  • min -- uint16
  • max -- uint16

Returns the callback configuration as set by set_co2_concentration_callback_configuration.

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

  • x: off, for option
  • o: outside, for option
  • i: inside, for option
  • <: smaller, for option
  • >: greater, for option
BrickletCO2V2.set_temperature_callback_configuration
Function ID:

14

Request:
  • period -- uint32
  • value_has_to_change -- bool
  • option -- char
  • min -- int16
  • max -- int16
Response:

no response

The period in ms 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 default value is (0, false, 'x', 0, 0).

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

  • x: off, for option
  • o: outside, for option
  • i: inside, for option
  • <: smaller, for option
  • >: greater, for option
BrickletCO2V2.get_temperature_callback_configuration
Function ID:

15

Request:

empty payload

Response:
  • period -- uint32
  • value_has_to_change -- bool
  • option -- char
  • min -- int16
  • max -- int16

Returns the callback configuration as set by set_temperature_callback_configuration.

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

  • x: off, for option
  • o: outside, for option
  • i: inside, for option
  • <: smaller, for option
  • >: greater, for option
BrickletCO2V2.set_humidity_callback_configuration
Function ID:

18

Request:
  • period -- uint32
  • value_has_to_change -- bool
  • option -- char
  • min -- uint16
  • max -- uint16
Response:

no response

The period in ms 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 default value is (0, false, 'x', 0, 0).

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

  • x: off, for option
  • o: outside, for option
  • i: inside, for option
  • <: smaller, for option
  • >: greater, for option
BrickletCO2V2.get_humidity_callback_configuration
Function ID:

19

Request:

empty payload

Response:
  • period -- uint32
  • value_has_to_change -- bool
  • option -- char
  • min -- uint16
  • max -- uint16

Returns the callback configuration as set by set_humidity_callback_configuration.

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

  • x: off, for option
  • o: outside, for option
  • i: inside, for option
  • <: smaller, for option
  • >: greater, for option

Callbacks

BrickletCO2V2.CALLBACK_ALL_VALUES
Function ID:

8

Response:
  • co2_concentration -- uint16
  • temperature -- int16
  • humidity -- uint16

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.

BrickletCO2V2.CALLBACK_CO2_CONCENTRATION
Function ID:

12

Response:
  • co2_concentration -- uint16

This callback is triggered periodically according to the configuration set by set_co2_concentration_callback_configuration.

The response value is the same as get_co2_concentration.

BrickletCO2V2.CALLBACK_TEMPERATURE
Function ID:

16

Response:
  • temperature -- int16

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

The response value is the same as get_temperature.

BrickletCO2V2.CALLBACK_HUMIDITY
Function ID:

20

Response:
  • humidity -- uint16

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

The response value is the same as get_humidity.