MQTT - Industrial Dual Relay Bricklet

This is the description of the MQTT API bindings for the Industrial Dual Relay Bricklet. General information and technical specifications for the Industrial Dual Relay Bricklet 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 Relay Bricklet

setup:
    # Turn relays alternating on/off 10 times with 1 second delay
    for i in 0 1 2 3 4; do
    
        wait for 1s 
    
        publish '{"channel0": true, "channel1": false}' to tinkerforge/request/industrial_dual_relay_bricklet/XYZ/set_value 
    
        wait for 1s 
    
        publish '{"channel0": false, "channel1": true}' to tinkerforge/request/industrial_dual_relay_bricklet/XYZ/set_value 
    
    done

API

All published payloads to and from the MQTT bindings are in JSON format.

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

Basic Functions

request/industrial_dual_relay_bricklet/<UID>/set_value
Request:
  • channel0 – Type: bool
  • channel1 – Type: bool
Response:
  • no response

Sets the state of the relays, true means on and false means off. For example: (true, false) turns relay 0 on and relay 1 off.

If you just want to set one of the relays and don't know the current state of the other relay, you can get the state with request/industrial_dual_relay_bricklet/<UID>/get_value or you can use request/industrial_dual_relay_bricklet/<UID>/set_selected_value.

All running monoflop timers will be aborted if this function is called.

The default value is (false, false).

request/industrial_dual_relay_bricklet/<UID>/get_value
Request:
  • empty payload
Response:
  • channel0 – Type: bool
  • channel1 – Type: bool

Returns the state of the relays, true means on and false means off.

Advanced Functions

request/industrial_dual_relay_bricklet/<UID>/set_monoflop
Request:
  • channel – Type: int, Range: [0 to 255]
  • value – Type: bool
  • time – Type: int, Range: [0 to 232 - 1]
Response:
  • no response

The first parameter can be 0 or 1 (relay 0 or relay 1). The second parameter is the desired state of the relay (true means on and false means off). The third parameter indicates the time (in ms) that the relay should hold the state.

If this function is called with the parameters (1, true, 1500): Relay 1 will turn on and in 1.5s it will turn off again.

A monoflop can be used as a failsafe mechanism. For example: Lets assume you have a RS485 bus and a Industrial Dual Relay Bricklet connected to one of the slave stacks. You can now call this function every second, with a time parameter of two seconds. The relay will be on all the time. If now the RS485 connection is lost, the relay will turn off in at most two seconds.

request/industrial_dual_relay_bricklet/<UID>/get_monoflop
Request:
  • channel – Type: int, Range: [0 to 255]
Response:
  • value – Type: bool
  • time – Type: int, Range: [0 to 232 - 1]
  • time_remaining – Type: int, Range: [0 to 232 - 1]

Returns (for the given relay) the current state and the time as set by request/industrial_dual_relay_bricklet/<UID>/set_monoflop as well as the remaining time until the state flips.

If the timer is not running currently, the remaining time will be returned as 0.

request/industrial_dual_relay_bricklet/<UID>/set_selected_value
Request:
  • channel – Type: int, Range: [0 to 255]
  • value – Type: bool
Response:
  • no response

Sets the state of the selected relay (0 or 1), true means on and false means off.

A running monoflop timer for the selected relay will be aborted if this function is called.

The other relay remains untouched.

request/industrial_dual_relay_bricklet/<UID>/get_spitfp_error_count
Request:
  • empty payload
Response:
  • error_count_ack_checksum – Type: int, Range: [0 to 232 - 1]
  • error_count_message_checksum – Type: int, Range: [0 to 232 - 1]
  • error_count_frame – Type: int, Range: [0 to 232 - 1]
  • error_count_overflow – Type: int, 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.

request/industrial_dual_relay_bricklet/<UID>/set_bootloader_mode
Request:
  • mode – Type: int, Range: See symbols
Response:
  • status – Type: int, Range: See 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_relay_bricklet/<UID>/get_bootloader_mode
Request:
  • empty payload
Response:
  • mode – Type: int, Range: See symbols

Returns the current bootloader mode, see request/industrial_dual_relay_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_relay_bricklet/<UID>/set_write_firmware_pointer
Request:
  • pointer – Type: int, Range: [0 to 232 - 1]
Response:
  • no response

Sets the firmware pointer for request/industrial_dual_relay_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_relay_bricklet/<UID>/write_firmware
Request:
  • data – Type: [int, ...], Length: 64, Range: [0 to 255]
Response:
  • status – Type: int, Range: [0 to 255]

Writes 64 Bytes of firmware at the position as written by request/industrial_dual_relay_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_relay_bricklet/<UID>/set_status_led_config
Request:
  • config – Type: int, Range: See symbols
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 symbols are available for this function:

For config:

  • "Off" = 0
  • "On" = 1
  • "ShowHeartbeat" = 2
  • "ShowStatus" = 3
request/industrial_dual_relay_bricklet/<UID>/get_status_led_config
Request:
  • empty payload
Response:
  • config – Type: int, Range: See symbols

Returns the configuration as set by request/industrial_dual_relay_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_relay_bricklet/<UID>/get_chip_temperature
Request:
  • empty payload
Response:
  • temperature – Type: int, Range: [-215 to 215 - 1]

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_relay_bricklet/<UID>/reset
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!

request/industrial_dual_relay_bricklet/<UID>/write_uid
Request:
  • uid – Type: int, 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.

request/industrial_dual_relay_bricklet/<UID>/read_uid
Request:
  • empty payload
Response:
  • uid – Type: int, Range: [0 to 232 - 1]

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

request/industrial_dual_relay_bricklet/<UID>/get_identity
Request:
  • empty payload
Response:
  • uid – Type: string, Length: up to 8
  • connected_uid – Type: string, Length: up to 8
  • position – Type: char
  • hardware_version – Type: [int, ...], Length: 3, Range: [0 to 255]
  • firmware_version – Type: [int, ...], Length: 3, Range: [0 to 255]
  • device_identifier – Type: int, Range: [0 to 216 - 1]
  • _display_name – Type: 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 Relay's name in a human readable form.

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_relay_bricklet/<UID>/monoflop_done
Register Request:
  • register – Type: bool
Callback Response:
  • channel – Type: int, Range: [0 to 255]
  • value – Type: bool

A callback can be registered for this event by publishing to the .../register/industrial_dual_relay_bricklet/<UID>/monoflop_done[/<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_relay_bricklet/<UID>/monoflop_done[/<SUFFIX>] topic for each registered suffix.

This callback is triggered whenever a monoflop timer reaches 0. The parameter contain the relay (0 or 1) and the current state of the relay (the state after the monoflop).