MQTT - Industrial Digital Out 4 Bricklet

This is the description of the MQTT API bindings for the Industrial Digital Out 4 Bricklet. General information and technical specifications for the Industrial Digital Out 4 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 Digital Out 4 Bricklet

setup:
    # Set pins alternating high/low 10 times with 100ms delay
    for i in 0 1 2 3 4 5 6 7 8 9; do
    
        wait for 0.1s 
    
        publish '{"value_mask": 1}' to tinkerforge/request/industrial_digital_out_4_bricklet/XYZ/set_value  # 1 << 0 = 1
    
        wait for 0.1s 
    
        publish '{"value_mask": 2}' to tinkerforge/request/industrial_digital_out_4_bricklet/XYZ/set_value  # 1 << 1 = 2
    
        wait for 0.1s 
    
        publish '{"value_mask": 4}' to tinkerforge/request/industrial_digital_out_4_bricklet/XYZ/set_value  # 1 << 2 = 4
    
        wait for 0.1s 
    
        publish '{"value_mask": 8}' to tinkerforge/request/industrial_digital_out_4_bricklet/XYZ/set_value  # 1 << 3 = 8
    
    done

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_digital_out_4_bricklet/<UID>/set_value
Request payload:
 
  • value_mask -- int

Sets the output value with a bitmask (16bit). A 1 in the bitmask means high and a 0 in the bitmask means low.

For example: The value 3 or 0b0011 will turn pins 0-1 high and the other pins low.

If no groups are used (see request/industrial_digital_out_4_bricklet/<UID>/set_group), the pins correspond to the markings on the Digital Out 4 Bricklet.

If groups are used, the pins correspond to the element in the group. Element 1 in the group will get pins 0-3, element 2 pins 4-7, element 3 pins 8-11 and element 4 pins 12-15.

request/industrial_digital_out_4_bricklet/<UID>/get_value
Response payload:
 
  • value_mask -- int

Returns the bitmask as set by request/industrial_digital_out_4_bricklet/<UID>/set_value.

request/industrial_digital_out_4_bricklet/<UID>/set_selected_values
Request payload:
 
  • selection_mask -- int
  • value_mask -- int

Sets the output value with a bitmask, according to the selection mask. The bitmask is 16 bit long, true refers to high and false refers to low.

For example: The values (3, 1) or (0b0011, 0b0001) will turn pin 0 high, pin 1 low the other pins remain untouched.

If no groups are used (see request/industrial_digital_out_4_bricklet/<UID>/set_group), the pins correspond to the markings on the Digital Out 4 Bricklet.

If groups are used, the pins correspond to the element in the group. Element 1 in the group will get pins 0-3, element 2 pins 4-7, element 3 pins 8-11 and element 4 pins 12-15.

Advanced Functions

request/industrial_digital_out_4_bricklet/<UID>/set_monoflop
Request payload:
 
  • selection_mask -- int
  • value_mask -- int
  • time -- int

Configures a monoflop of the pins specified by the first parameter bitmask.

The second parameter is a bitmask with the desired value of the specified pins. A 1 in the bitmask means high and a 0 in the bitmask means low.

The third parameter indicates the time (in ms) that the pins should hold the value.

If this function is called with the parameters (9, 1, 1500) or (0b1001, 0b0001, 1500): Pin 0 will get high and pin 3 will get low. In 1.5s pin 0 will get low and pin 3 will get high again.

A monoflop can be used as a fail-safe mechanism. For example: Lets assume you have a RS485 bus and a Digital Out 4 Bricklet connected to one of the slave stacks. You can now call this function every second, with a time parameter of two seconds and pin 0 high. Pin 0 will be high all the time. If now the RS485 connection is lost, then pin 0 will turn low in at most two seconds.

request/industrial_digital_out_4_bricklet/<UID>/get_monoflop
Request payload:
 
  • pin -- int
Response payload:
 
  • value -- int
  • time -- int
  • time_remaining -- int

Returns (for the given pin) the current value and the time as set by request/industrial_digital_out_4_bricklet/<UID>/set_monoflop as well as the remaining time until the value flips.

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

request/industrial_digital_out_4_bricklet/<UID>/set_group
Request payload:
 
  • group -- string

Sets a group of Digital Out 4 Bricklets that should work together. You can find Bricklets that can be grouped together with request/industrial_digital_out_4_bricklet/<UID>/get_available_for_group.

The group consists of 4 elements. Element 1 in the group will get pins 0-3, element 2 pins 4-7, element 3 pins 8-11 and element 4 pins 12-15.

Each element can either be one of the ports ('a' to 'd') or 'n' if it should not be used.

For example: If you have two Digital Out 4 Bricklets connected to port A and port B respectively, you could call with ['a', 'b', 'n', 'n'].

Now the pins on the Digital Out 4 on port A are assigned to 0-3 and the pins on the Digital Out 4 on port B are assigned to 4-7. It is now possible to call request/industrial_digital_out_4_bricklet/<UID>/set_value and control two Bricklets at the same time.

request/industrial_digital_out_4_bricklet/<UID>/get_group
Response payload:
 
  • group -- string

Returns the group as set by request/industrial_digital_out_4_bricklet/<UID>/set_group

request/industrial_digital_out_4_bricklet/<UID>/get_available_for_group
Response payload:
 
  • available -- int

Returns a bitmask of ports that are available for grouping. For example the value 5 or 0b0101 means: Port A and port C are connected to Bricklets that can be grouped together.

request/industrial_digital_out_4_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 Digital Out 4's name in a human readable form.

Callback Configuration Functions

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_digital_out_4_bricklet/<UID>/monoflop_done
Request payload:
 
  • register -- bool
Response payload:
 
  • selection_mask -- int
  • value_mask -- int

A callback can be registered for this event by publishing to the .../register/industrial_digital_out_4_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_digital_out_4_bricklet/<UID>/monoflop_done[/<SUFFIX>] topic for each registered suffix.

This callback is triggered whenever a monoflop timer reaches 0. The callback payload members contain the involved pins and the current value of the pins (the value after the monoflop).