Modbus - Distance IR Bricklet

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

API

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

Basic Functions

BrickletDistanceIR.get_distance
Function ID:

1

Request:

empty payload

Response:
  • distance -- uint16

Returns the distance measured by the sensor. The value is in mm and possible distance ranges are 40 to 300, 100 to 800 and 200 to 1500, depending on the selected IR sensor.

If you want to get the distance periodically, it is recommended to use the CALLBACK_DISTANCE callback and set the period with set_distance_callback_period.

Advanced Functions

BrickletDistanceIR.get_analog_value
Function ID:

2

Request:

empty payload

Response:
  • value -- uint16

Returns the value as read by a 12-bit analog-to-digital converter. The value is between 0 and 4095.

Note

The value returned by get_distance is averaged over several samples to yield less noise, while get_analog_value gives back raw unfiltered analog values. The only reason to use get_analog_value is, if you need the full resolution of the analog-to-digital converter.

If you want the analog value periodically, it is recommended to use the CALLBACK_ANALOG_VALUE callback and set the period with set_analog_value_callback_period.

BrickletDistanceIR.set_sampling_point
Function ID:

3

Request:
  • position -- uint8
  • distance -- uint16
Response:

no response

Sets a sampling point value to a specific position of the lookup table. The lookup table comprises 128 equidistant analog values with corresponding distances.

If you measure a distance of 50cm at the analog value 2048, you should call this function with (64, 5000). The utilized analog-to-digital converter has a resolution of 12 bit. With 128 sampling points on the whole range, this means that every sampling point has a size of 32 analog values. Thus the analog value 2048 has the corresponding sampling point 64 = 2048/32.

Sampling points are saved on the EEPROM of the Distance IR Bricklet and loaded again on startup.

Note

An easy way to calibrate the sampling points of the Distance IR Bricklet is implemented in the Brick Viewer. If you want to calibrate your Bricklet it is highly recommended to use this implementation.

BrickletDistanceIR.get_sampling_point
Function ID:

4

Request:
  • position -- uint8
Response:
  • distance -- uint16

Returns the distance to a sampling point position as set by set_sampling_point.

BrickletDistanceIR.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

BrickletDistanceIR.set_distance_callback_period
Function ID:

5

Request:
  • period -- uint32
Response:

no response

Sets the period in ms with which the CALLBACK_DISTANCE callback is triggered periodically. A value of 0 turns the callback off.

The CALLBACK_DISTANCE callback is only triggered if the distance has changed since the last triggering.

The default value is 0.

BrickletDistanceIR.get_distance_callback_period
Function ID:

6

Request:

empty payload

Response:
  • period -- uint32

Returns the period as set by set_distance_callback_period.

BrickletDistanceIR.set_analog_value_callback_period
Function ID:

7

Request:
  • period -- uint32
Response:

no response

Sets the period in ms with which the CALLBACK_ANALOG_VALUE callback is triggered periodically. A value of 0 turns the callback off.

The CALLBACK_ANALOG_VALUE callback is only triggered if the analog value has changed since the last triggering.

The default value is 0.

BrickletDistanceIR.get_analog_value_callback_period
Function ID:

8

Request:

empty payload

Response:
  • period -- uint32

Returns the period as set by set_analog_value_callback_period.

BrickletDistanceIR.set_distance_callback_threshold
Function ID:

9

Request:
  • option -- char
  • min -- uint16
  • max -- uint16
Response:

no response

Sets the thresholds for the CALLBACK_DISTANCE_REACHED callback.

The following options are possible:

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

The default value is ('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
BrickletDistanceIR.get_distance_callback_threshold
Function ID:

10

Request:

empty payload

Response:
  • option -- char
  • min -- uint16
  • max -- uint16

Returns the threshold as set by set_distance_callback_threshold.

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
BrickletDistanceIR.set_analog_value_callback_threshold
Function ID:

11

Request:
  • option -- char
  • min -- uint16
  • max -- uint16
Response:

no response

Sets the thresholds for the CALLBACK_ANALOG_VALUE_REACHED callback.

The following options are possible:

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

The default value is ('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
BrickletDistanceIR.get_analog_value_callback_threshold
Function ID:

12

Request:

empty payload

Response:
  • option -- char
  • min -- uint16
  • max -- uint16

Returns the threshold as set by set_analog_value_callback_threshold.

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
BrickletDistanceIR.set_debounce_period
Function ID:

13

Request:
  • debounce -- uint32
Response:

no response

Sets the period in ms with which the threshold callbacks

are triggered, if the thresholds

keep being reached.

The default value is 100.

BrickletDistanceIR.get_debounce_period
Function ID:

14

Request:

empty payload

Response:
  • debounce -- uint32

Returns the debounce period as set by set_debounce_period.

Callbacks

BrickletDistanceIR.CALLBACK_DISTANCE
Function ID:

15

Response:
  • distance -- uint16

This callback is triggered periodically with the period that is set by set_distance_callback_period. The response value is the distance of the sensor.

The CALLBACK_DISTANCE callback is only triggered if the distance has changed since the last triggering.

BrickletDistanceIR.CALLBACK_ANALOG_VALUE
Function ID:

16

Response:
  • value -- uint16

This callback is triggered periodically with the period that is set by set_analog_value_callback_period. The response value is the analog value of the sensor.

The CALLBACK_ANALOG_VALUE callback is only triggered if the analog value has changed since the last triggering.

BrickletDistanceIR.CALLBACK_DISTANCE_REACHED
Function ID:

17

Response:
  • distance -- uint16

This callback is triggered when the threshold as set by set_distance_callback_threshold is reached. The response value is the distance of the sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by set_debounce_period.

BrickletDistanceIR.CALLBACK_ANALOG_VALUE_REACHED
Function ID:

18

Response:
  • value -- uint16

This callback is triggered when the threshold as set by set_analog_value_callback_threshold is reached. The response value is the analog value of the sensor.

If the threshold keeps being reached, the callback is triggered periodically with the period as set by set_debounce_period.