MQTT - Industrial Dual 0-20mA Bricklet 2.0

This is the description of the MQTT API bindings for the Industrial Dual 0-20mA Bricklet 2.0. General information and technical specifications for the Industrial Dual 0-20mA Bricklet 2.0 are summarized in its hardware description.

An installation guide for the MQTT API bindings is part of their general description.

Examples

The example code below is Public Domain (CC0 1.0).

Simple

Download (example-simple.txt)

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# Change XYZ to the UID of your Industrial Dual 0-20mA Bricklet 2.0

setup:
    # Get current current from channel 0
    subscribe to tinkerforge/response/industrial_dual_0_20ma_v2_bricklet/XYZ/get_current
    publish '{"channel": 0}' to tinkerforge/request/industrial_dual_0_20ma_v2_bricklet/XYZ/get_current

Callback

Download (example-callback.txt)

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# Change XYZ to the UID of your Industrial Dual 0-20mA Bricklet 2.0

setup:
    # Handle incoming current callbacks
    subscribe to tinkerforge/callback/industrial_dual_0_20ma_v2_bricklet/XYZ/current
    publish '{"register": true}' to tinkerforge/register/industrial_dual_0_20ma_v2_bricklet/XYZ/current # Register current callback
    
    # Set period for current (channel 0) callback to 1s (1000ms) without a threshold
    publish '{"channel": 0, "period": 1000, "value_has_to_change": false, "option": "off", "min": 0, "max": 0}' to tinkerforge/request/industrial_dual_0_20ma_v2_bricklet/XYZ/set_current_callback_configuration

Threshold

Download (example-threshold.txt)

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# Change XYZ to the UID of your Industrial Dual 0-20mA Bricklet 2.0

setup:
    # Handle incoming current callbacks
    subscribe to tinkerforge/callback/industrial_dual_0_20ma_v2_bricklet/XYZ/current
    publish '{"register": true}' to tinkerforge/register/industrial_dual_0_20ma_v2_bricklet/XYZ/current # Register current callback
    
    # Configure threshold for current (channel 0) "greater than 10 mA"
    # with a debounce period of 10s (10000ms)
    publish '{"channel": 0, "period": 10000, "value_has_to_change": false, "option": "greater", "min": 10000000, "max": 0}' to tinkerforge/request/industrial_dual_0_20ma_v2_bricklet/XYZ/set_current_callback_configuration

API

All published payload to an from the MQTT bindings is in the JSON format.

If an error occures, the bindings publish a JSON object containing the error message as attribute "_ERROR". It is published on the corresponding response topic: .../response/... for .../request/... and .../callback/... for .../register/....

Basic Functions

request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_current
Request payload:
 
  • channel -- int
Response payload:
 
  • current -- int

Returns the current of the specified channel. The value is in nA and between 0nA and 22505322nA (22.5mA).

It is possible to detect if an IEC 60381-1 compatible sensor is connected and if it works probably.

If the returned current is below 4mA, there is likely no sensor connected or the connected sensor is defective. If the returned current is over 20mA, there might be a short circuit or the sensor is defective.

If you want to get the value periodically, it is recommended to use the register/industrial_dual_0_20ma_v2_bricklet/<UID>/current callback. You can set the callback configuration with request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_current_callback_configuration.

request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_channel_led_config
Request payload:
 
  • channel -- int
  • config -- int (has symbols)

Each channel has a corresponding LED. You can turn the LED off, on or show a heartbeat. You can also set the LED to "Channel Status". In this mode the LED can either be turned on with a pre-defined threshold or the intensity of the LED can change with the measured value.

You can configure the channel status behavior with request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_channel_led_status_config.

By default all channel LEDs are configured as "Channel Status".

The following symbols are available for this function:

for config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
  • "ShowChannelStatus" = 3
request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_channel_led_config
Request payload:
 
  • channel -- int
Response payload:
 
  • config -- int (has symbols)

Returns the channel LED configuration as set by request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_channel_led_config

The following symbols are available for this function:

for config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
  • "ShowChannelStatus" = 3
request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_channel_led_status_config
Request payload:
 
  • channel -- int
  • min -- int
  • max -- int
  • config -- int (has symbols)

Sets the channel LED status config. This config is used if the channel LED is configured as "Channel Status", see request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_channel_led_config.

For each channel you can choose between threshold and intensity mode.

In threshold mode you can define a positive or a negative threshold. For a positive threshold set the "min" parameter to the threshold value in nA above which the LED should turn on and set the "max" parameter to 0. Example: If you set a positive threshold of 10mA, the LED will turn on as soon as the current exceeds 10mA and turn off again if it goes below 10mA. For a negative threshold set the "max" parameter to the threshold value in nA below which the LED should turn on and set the "min" parameter to 0. Example: If you set a negative threshold of 10mA, the LED will turn on as soon as the current goes below 10mA and the LED will turn off when the current exceeds 10mA.

In intensity mode you can define a range in nA that is used to scale the brightness of the LED. Example with min=4mA and max=20mA: The LED is off at 4mA and below, on at 20mA and above and the brightness is linearly scaled between the values 4mA and 20mA. If the min value is greater than the max value, the LED brightness is scaled the other way around.

By default the channel LED status config is set to intensity with min=4mA and max=20mA.

The following symbols are available for this function:

for config:

  • "Threshold" = 0
  • "Intensity" = 1
request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_channel_led_status_config
Request payload:
 
  • channel -- int
Response payload:
 
  • min -- int
  • max -- int
  • config -- int (has symbols)

Returns the channel LED status configuration as set by request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_channel_led_status_config.

The following symbols are available for this function:

for config:

  • "Threshold" = 0
  • "Intensity" = 1

Advanced Functions

request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_sample_rate
Request payload:
 
  • rate -- int (has symbols)

Sets the sample rate to either 240, 60, 15 or 4 samples per second. The resolution for the rates is 12, 14, 16 and 18 bit respectively.

Value Description
0 240 samples per second, 12 bit resolution
1 60 samples per second, 14 bit resolution
2 15 samples per second, 16 bit resolution
3 4 samples per second, 18 bit resolution

The default value is 3 (4 samples per second with 18 bit resolution).

The following symbols are available for this function:

for rate:

  • "240SPS" = 0
  • "60SPS" = 1
  • "15SPS" = 2
  • "4SPS" = 3
request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_sample_rate
Response payload:
 
  • rate -- int (has symbols)

Returns the gain as set by request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_sample_rate.

The following symbols are available for this function:

for rate:

  • "240SPS" = 0
  • "60SPS" = 1
  • "15SPS" = 2
  • "4SPS" = 3
request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_gain
Request payload:
 
  • gain -- int (has symbols)

Sets a gain between 1x and 8x. If you want to measure a very small current, you can increase the gain to get some more resolution.

Example: If you measure 0.5mA with a gain of 8x the return value will be 4mA.

The default gain is 1x.

The following symbols are available for this function:

for gain:

  • "1x" = 0
  • "2x" = 1
  • "4x" = 2
  • "8x" = 3
request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_gain
Response payload:
 
  • gain -- int (has symbols)

Returns the gain as set by request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_gain.

The following symbols are available for this function:

for gain:

  • "1x" = 0
  • "2x" = 1
  • "4x" = 2
  • "8x" = 3
request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_spitfp_error_count
Response payload:
 
  • error_count_ack_checksum -- int
  • error_count_message_checksum -- int
  • error_count_frame -- int
  • error_count_overflow -- int

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.

request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_bootloader_mode
Request payload:
 
  • mode -- int (has symbols)
Response payload:
 
  • status -- int (has symbols)

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 symbols are available for this function:

for mode:

  • "Bootloader" = 0
  • "Firmware" = 1
  • "BootloaderWaitForReboot" = 2
  • "FirmwareWaitForReboot" = 3
  • "FirmwareWaitForEraseAndReboot" = 4

for status:

  • "OK" = 0
  • "InvalidMode" = 1
  • "NoChange" = 2
  • "EntryFunctionNotPresent" = 3
  • "DeviceIdentifierIncorrect" = 4
  • "CRCMismatch" = 5
request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_bootloader_mode
Response payload:
 
  • mode -- int (has symbols)

Returns the current bootloader mode, see request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_bootloader_mode.

The following symbols are available for this function:

for mode:

  • "Bootloader" = 0
  • "Firmware" = 1
  • "BootloaderWaitForReboot" = 2
  • "FirmwareWaitForReboot" = 3
  • "FirmwareWaitForEraseAndReboot" = 4
request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_write_firmware_pointer
Request payload:
 
  • pointer -- int

Sets the firmware pointer for request/industrial_dual_0_20ma_v2_bricklet/<UID>/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.

request/industrial_dual_0_20ma_v2_bricklet/<UID>/write_firmware
Request payload:
 
  • data -- [int,... (x64)]
Response payload:
 
  • status -- int

Writes 64 Bytes of firmware at the position as written by request/industrial_dual_0_20ma_v2_bricklet/<UID>/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.

request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_status_led_config
Request payload:
 
  • config -- int (has symbols)

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 symbols are available for this function:

for config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
  • "ShowStatus" = 3
request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_status_led_config
Response payload:
 
  • config -- int (has symbols)

Returns the configuration as set by request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_status_led_config

The following symbols are available for this function:

for config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
  • "ShowStatus" = 3
request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_chip_temperature
Response payload:
 
  • temperature -- int

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.

request/industrial_dual_0_20ma_v2_bricklet/<UID>/reset

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!

request/industrial_dual_0_20ma_v2_bricklet/<UID>/write_uid
Request payload:
 
  • uid -- int

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.

request/industrial_dual_0_20ma_v2_bricklet/<UID>/read_uid
Response payload:
 
  • uid -- int

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

request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_identity
Response payload:
 
  • uid -- string
  • connected_uid -- string
  • position -- string
  • hardware_version -- [int,int,int]
  • firmware_version -- [int,int,int]
  • device_identifier -- int (has symbols)
  • _display_name -- string

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. If symbolic output is not disabled, the device identifier is mapped to the corresponding name in the format used in topics.

The display name contains the Industrial Dual 0-20mA 2.0's name in a human readable form.

Callback Configuration Functions

request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_current_callback_configuration
Request payload:
 
  • channel -- int
  • period -- int
  • value_has_to_change -- bool
  • option -- string (has symbols)
  • min -- int
  • max -- int

The period in ms is the period with which the register/industrial_dual_0_20ma_v2_bricklet/<UID>/current 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 register/industrial_dual_0_20ma_v2_bricklet/<UID>/current 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 symbols are available for this function:

for option:

  • "Off" = 'x'
  • "Outside" = 'o'
  • "Inside" = 'i'
  • "Smaller" = '<'
  • "Greater" = '>'
request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_current_callback_configuration
Request payload:
 
  • channel -- int
Response payload:
 
  • period -- int
  • value_has_to_change -- bool
  • option -- string (has symbols)
  • min -- int
  • max -- int

Returns the callback configuration as set by request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_current_callback_configuration.

The following symbols are available for this function:

for option:

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

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done with the corresponding .../register/... topic and an optional suffix. This suffix can be used to deregister the callback later.

Note

Using callbacks for recurring events is always preferred compared to using getters. It will use less USB bandwidth and the latency will be a lot better, since there is no round trip time.

register/industrial_dual_0_20ma_v2_bricklet/<UID>/current
Request payload:
 
  • register -- bool
Response payload:
 
  • channel -- int
  • current -- int

A callback can be registered for this event by publishing to the .../register/industrial_dual_0_20ma_v2_bricklet/<UID>/current[/<SUFFIX>] topic with the payload "true". An added callback can be removed by publishing to the same topic with the payload "false". To support multiple (de)registrations, e.g. for message filtering, an optional suffix can be used.

If the callback is triggered, a message with it's payload is published under the corresponding .../callback/industrial_dual_0_20ma_v2_bricklet/<UID>/current[/<SUFFIX>] topic for each registered suffix.

This callback is triggered periodically according to the configuration set by request/industrial_dual_0_20ma_v2_bricklet/<UID>/set_current_callback_configuration.

The callback payload is the same as request/industrial_dual_0_20ma_v2_bricklet/<UID>/get_current.