Visual Basic .NET - Line Bricklet

This is the description of the Visual Basic .NET API bindings for the Line Bricklet. General information and technical specifications for the Line Bricklet are summarized in its hardware description.

An installation guide for the Visual Basic .NET API bindings is part of their general description.

Examples

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

Simple

Download (ExampleSimple.vb)

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Imports System
Imports Tinkerforge

Module ExampleSimple
    Const HOST As String = "localhost"
    Const PORT As Integer = 4223
    Const UID As String = "XYZ" ' Change XYZ to the UID of your Line Bricklet

    Sub Main()
        Dim ipcon As New IPConnection() ' Create IP connection
        Dim l As New BrickletLine(UID, ipcon) ' Create device object

        ipcon.Connect(HOST, PORT) ' Connect to brickd
        ' Don't use device before ipcon is connected

        ' Get current reflectivity
        Dim reflectivity As Integer = l.GetReflectivity()
        Console.WriteLine("Reflectivity: " + reflectivity.ToString())

        Console.WriteLine("Press key to exit")
        Console.ReadLine()
        ipcon.Disconnect()
    End Sub
End Module

Callback

Download (ExampleCallback.vb)

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Imports System
Imports Tinkerforge

Module ExampleCallback
    Const HOST As String = "localhost"
    Const PORT As Integer = 4223
    Const UID As String = "XYZ" ' Change XYZ to the UID of your Line Bricklet

    ' Callback subroutine for reflectivity callback
    Sub ReflectivityCB(ByVal sender As BrickletLine, ByVal reflectivity As Integer)
        Console.WriteLine("Reflectivity: " + reflectivity.ToString())
    End Sub

    Sub Main()
        Dim ipcon As New IPConnection() ' Create IP connection
        Dim l As New BrickletLine(UID, ipcon) ' Create device object

        ipcon.Connect(HOST, PORT) ' Connect to brickd
        ' Don't use device before ipcon is connected

        ' Register reflectivity callback to subroutine ReflectivityCB
        AddHandler l.ReflectivityCallback, AddressOf ReflectivityCB

        ' Set period for reflectivity callback to 1s (1000ms)
        ' Note: The reflectivity callback is only called every second
        '       if the reflectivity has changed since the last call!
        l.SetReflectivityCallbackPeriod(1000)

        Console.WriteLine("Press key to exit")
        Console.ReadLine()
        ipcon.Disconnect()
    End Sub
End Module

Threshold

Download (ExampleThreshold.vb)

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Imports System
Imports Tinkerforge

Module ExampleThreshold
    Const HOST As String = "localhost"
    Const PORT As Integer = 4223
    Const UID As String = "XYZ" ' Change XYZ to the UID of your Line Bricklet

    ' Callback subroutine for reflectivity reached callback
    Sub ReflectivityReachedCB(ByVal sender As BrickletLine, _
                              ByVal reflectivity As Integer)
        Console.WriteLine("Reflectivity: " + reflectivity.ToString())
    End Sub

    Sub Main()
        Dim ipcon As New IPConnection() ' Create IP connection
        Dim l As New BrickletLine(UID, ipcon) ' Create device object

        ipcon.Connect(HOST, PORT) ' Connect to brickd
        ' Don't use device before ipcon is connected

        ' Get threshold callbacks with a debounce time of 1 second (1000ms)
        l.SetDebouncePeriod(1000)

        ' Register reflectivity reached callback to subroutine ReflectivityReachedCB
        AddHandler l.ReflectivityReachedCallback, AddressOf ReflectivityReachedCB

        ' Configure threshold for reflectivity "greater than 2000"
        l.SetReflectivityCallbackThreshold(">"C, 2000, 0)

        Console.WriteLine("Press key to exit")
        Console.ReadLine()
        ipcon.Disconnect()
    End Sub
End Module

API

Since Visual Basic .NET does not support multiple return values directly, we use the ByRef keyword to return multiple values from a function.

All functions and procedures listed below are thread-safe.

Basic Functions

Class BrickletLine(ByVal uid As String, ByVal ipcon As IPConnection)

Creates an object with the unique device ID uid:

Dim line As New BrickletLine("YOUR_DEVICE_UID", ipcon)

This object can then be used after the IP Connection is connected (see examples above).

Function BrickletLine.GetReflectivity() As Integer

Returns the currently measured reflectivity. The reflectivity is a value between 0 (not reflective) and 4095 (very reflective).

Usually black has a low reflectivity while white has a high reflectivity.

If you want to get the reflectivity periodically, it is recommended to use the ReflectivityCallback callback and set the period with SetReflectivityCallbackPeriod().

Advanced Functions

Function BrickletLine.GetAPIVersion() As Byte()

Returns the version of the API definition (major, minor, revision) implemented by this API bindings. This is neither the release version of this API bindings nor does it tell you anything about the represented Brick or Bricklet.

Function BrickletLine.GetResponseExpected(ByVal functionId As Byte) As Boolean

Returns the response expected flag for the function specified by the function ID parameter. It is true if the function is expected to send a response, false otherwise.

For getter functions this is enabled by default and cannot be disabled, because those functions will always send a response. For callback configuration functions it is enabled by default too, but can be disabled by SetResponseExpected(). For setter functions it is disabled by default and can be enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

See SetResponseExpected() for the list of function ID constants available for this function.

Sub BrickletLine.SetResponseExpected(ByVal functionId As Byte, ByVal responseExpected As Boolean)

Changes the response expected flag of the function specified by the function ID parameter. This flag can only be changed for setter (default value: false) and callback configuration functions (default value: true). For getter functions it is always enabled.

Enabling the response expected flag for a setter function allows to detect timeouts and other error conditions calls of this setter as well. The device will then send a response for this purpose. If this flag is disabled for a setter function then no response is send and errors are silently ignored, because they cannot be detected.

The following function ID constants are available for this function:

  • BrickletLine.FUNCTION_SET_REFLECTIVITY_CALLBACK_PERIOD = 2
  • BrickletLine.FUNCTION_SET_REFLECTIVITY_CALLBACK_THRESHOLD = 4
  • BrickletLine.FUNCTION_SET_DEBOUNCE_PERIOD = 6
Sub BrickletLine.SetResponseExpectedAll(ByVal responseExpected As Boolean)

Changes the response expected flag for all setter and callback configuration functions of this device at once.

Sub BrickletLine.GetIdentity(ByRef uid As String, ByRef connectedUid As String, ByRef position As Char, ByRef hardwareVersion() As Byte, ByRef firmwareVersion() As Byte, ByRef deviceIdentifier As Integer)

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. There is also a constant for the device identifier of this Bricklet.

Callback Configuration Functions

Sub BrickletLine.SetReflectivityCallbackPeriod(ByVal period As Long)

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

The ReflectivityCallback callback is only triggered if the reflectivity has changed since the last triggering.

The default value is 0.

Function BrickletLine.GetReflectivityCallbackPeriod() As Long

Returns the period as set by SetReflectivityCallbackPeriod().

Sub BrickletLine.SetReflectivityCallbackThreshold(ByVal option As Char, ByVal min As Integer, ByVal max As Integer)

Sets the thresholds for the ReflectivityReachedCallback callback.

The following options are possible:

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

The default value is ('x', 0, 0).

The following constants are available for this function:

  • BrickletLine.THRESHOLD_OPTION_OFF = "x"C
  • BrickletLine.THRESHOLD_OPTION_OUTSIDE = "o"C
  • BrickletLine.THRESHOLD_OPTION_INSIDE = "i"C
  • BrickletLine.THRESHOLD_OPTION_SMALLER = "<"C
  • BrickletLine.THRESHOLD_OPTION_GREATER = ">"C
Sub BrickletLine.GetReflectivityCallbackThreshold(ByRef option As Char, ByRef min As Integer, ByRef max As Integer)

Returns the threshold as set by SetReflectivityCallbackThreshold().

The following constants are available for this function:

  • BrickletLine.THRESHOLD_OPTION_OFF = "x"C
  • BrickletLine.THRESHOLD_OPTION_OUTSIDE = "o"C
  • BrickletLine.THRESHOLD_OPTION_INSIDE = "i"C
  • BrickletLine.THRESHOLD_OPTION_SMALLER = "<"C
  • BrickletLine.THRESHOLD_OPTION_GREATER = ">"C
Sub BrickletLine.SetDebouncePeriod(ByVal debounce As Long)

Sets the period in ms with which the threshold callback

is triggered, if the threshold

keeps being reached.

The default value is 100.

Function BrickletLine.GetDebouncePeriod() As Long

Returns the debounce period as set by SetDebouncePeriod().

Callbacks

Callbacks can be registered to receive time critical or recurring data from the device. The registration is done by assigning a procedure to an callback property of the device object:

Sub MyCallback(ByVal sender As BrickletLine, ByVal value As Short)
    Console.WriteLine("Value: {0}", value)
End Sub

AddHandler line.ExampleCallback, AddressOf MyCallback

The available callback property and their type of parameters are described below.

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.

Event BrickletLine.ReflectivityCallback(ByVal sender As BrickletLine, ByVal reflectivity As Integer)

This callback is triggered periodically with the period that is set by SetReflectivityCallbackPeriod(). The parameter is the reflectivity of the sensor.

The ReflectivityCallback callback is only triggered if the reflectivity has changed since the last triggering.

Event BrickletLine.ReflectivityReachedCallback(ByVal sender As BrickletLine, ByVal reflectivity As Integer)

This callback is triggered when the threshold as set by SetReflectivityCallbackThreshold() is reached. The parameter is the reflectivity of the sensor.

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

Constants

Const BrickletLine.DEVICE_IDENTIFIER

This constant is used to identify a Line Bricklet.

The GetIdentity() function and the EnumerateCallback callback of the IP Connection have a deviceIdentifier parameter to specify the Brick's or Bricklet's type.

Const BrickletLine.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a Line Bricklet.