Visual Basic .NET - RS232 Bricklet

This is the description of the Visual Basic .NET API bindings for the RS232 Bricklet. General information and technical specifications for the RS232 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).

Loopback

Download (ExampleLoopback.vb)

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Imports System
Imports Tinkerforge

' For this example connect the RX1 and TX pin to receive the send message

Module ExampleLoopback
    Const HOST As String = "localhost"
    Const PORT As Integer = 4223
    Const UID As String = "XYZ" ' Change XYZ to the UID of your RS232 Bricklet

    ' Convert message to array of length 60 as needed by write
    Function StringToCharArray(ByVal message As String) As Char()
        Dim chars As Char() = message.ToCharArray()
        ReDim Preserve chars(60)
        Return chars
    End Function

    ' Assume that the message consists of ASCII characters and
    ' convert it from an array of chars to a string
    Function CharArrayToString(ByVal message As Char(), ByVal length As Byte) As String
        Return new String(message, 0, length)
    End Function

    ' Callback subroutine for read callback
    Sub ReadCB(ByVal sender As BrickletRS232, ByVal message As Char(), _
               ByVal length As Byte)
        Dim ascii as String = CharArrayToString(message, length)
        Console.WriteLine("Message (Length: {0}): ""{1}""", length, ascii)
    End Sub

    Sub Main()
        Dim ipcon As New IPConnection() ' Create IP connection
        Dim rs232 As New BrickletRS232(UID, ipcon) ' Create device object

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

        ' Register read callback to subroutine ReadCB
        AddHandler rs232.ReadCallback, AddressOf ReadCB

        ' Enable read callback
        rs232.EnableReadCallback()

        ' Write "test" string
        rs232.Write(StringToCharArray("test"), 4)

        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 BrickletRS232(ByVal uid As String, ByVal ipcon As IPConnection)

Creates an object with the unique device ID uid:

Dim rs232 As New BrickletRS232("YOUR_DEVICE_UID", ipcon)

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

Function BrickletRS232.Write(ByVal message() As Char, ByVal length As Byte) As Byte

Writes a string of up to 60 characters to the RS232 interface. The string can be binary data, ASCII or similar is not necessary.

The length of the string has to be given as an additional parameter.

The return value is the number of bytes that could be written.

See SetConfiguration() for configuration possibilities regarding baudrate, parity and so on.

Sub BrickletRS232.Read(ByRef message() As Char, ByRef length As Byte)

Returns the currently buffered message. The maximum length of message is 60. If the length is given as 0, there was no new data available.

Instead of polling with this function, you can also use callbacks. See EnableReadCallback() and ReadCallback callback.

Sub BrickletRS232.SetConfiguration(ByVal baudrate As Byte, ByVal parity As Byte, ByVal stopbits As Byte, ByVal wordlength As Byte, ByVal hardwareFlowcontrol As Byte, ByVal softwareFlowcontrol As Byte)

Sets the configuration for the RS232 communication. Available options:

  • Baudrate between 300 and 230400 baud.
  • Parity of none, odd, even or forced parity.
  • Stopbits can be 1 or 2.
  • Word length of 5 to 8.
  • Hard-/Software flow control can either be on or off but not both simultaneously on.

The default is: 115200 baud, parity none, 1 stop bit, word length 8, hard-/software flow control off.

The following constants are available for this function:

  • BrickletRS232.BAUDRATE_300 = 0
  • BrickletRS232.BAUDRATE_600 = 1
  • BrickletRS232.BAUDRATE_1200 = 2
  • BrickletRS232.BAUDRATE_2400 = 3
  • BrickletRS232.BAUDRATE_4800 = 4
  • BrickletRS232.BAUDRATE_9600 = 5
  • BrickletRS232.BAUDRATE_14400 = 6
  • BrickletRS232.BAUDRATE_19200 = 7
  • BrickletRS232.BAUDRATE_28800 = 8
  • BrickletRS232.BAUDRATE_38400 = 9
  • BrickletRS232.BAUDRATE_57600 = 10
  • BrickletRS232.BAUDRATE_115200 = 11
  • BrickletRS232.BAUDRATE_230400 = 12
  • BrickletRS232.PARITY_NONE = 0
  • BrickletRS232.PARITY_ODD = 1
  • BrickletRS232.PARITY_EVEN = 2
  • BrickletRS232.PARITY_FORCED_PARITY_1 = 3
  • BrickletRS232.PARITY_FORCED_PARITY_0 = 4
  • BrickletRS232.STOPBITS_1 = 1
  • BrickletRS232.STOPBITS_2 = 2
  • BrickletRS232.WORDLENGTH_5 = 5
  • BrickletRS232.WORDLENGTH_6 = 6
  • BrickletRS232.WORDLENGTH_7 = 7
  • BrickletRS232.WORDLENGTH_8 = 8
  • BrickletRS232.HARDWARE_FLOWCONTROL_OFF = 0
  • BrickletRS232.HARDWARE_FLOWCONTROL_ON = 1
  • BrickletRS232.SOFTWARE_FLOWCONTROL_OFF = 0
  • BrickletRS232.SOFTWARE_FLOWCONTROL_ON = 1
Sub BrickletRS232.GetConfiguration(ByRef baudrate As Byte, ByRef parity As Byte, ByRef stopbits As Byte, ByRef wordlength As Byte, ByRef hardwareFlowcontrol As Byte, ByRef softwareFlowcontrol As Byte)

Returns the configuration as set by SetConfiguration().

The following constants are available for this function:

  • BrickletRS232.BAUDRATE_300 = 0
  • BrickletRS232.BAUDRATE_600 = 1
  • BrickletRS232.BAUDRATE_1200 = 2
  • BrickletRS232.BAUDRATE_2400 = 3
  • BrickletRS232.BAUDRATE_4800 = 4
  • BrickletRS232.BAUDRATE_9600 = 5
  • BrickletRS232.BAUDRATE_14400 = 6
  • BrickletRS232.BAUDRATE_19200 = 7
  • BrickletRS232.BAUDRATE_28800 = 8
  • BrickletRS232.BAUDRATE_38400 = 9
  • BrickletRS232.BAUDRATE_57600 = 10
  • BrickletRS232.BAUDRATE_115200 = 11
  • BrickletRS232.BAUDRATE_230400 = 12
  • BrickletRS232.PARITY_NONE = 0
  • BrickletRS232.PARITY_ODD = 1
  • BrickletRS232.PARITY_EVEN = 2
  • BrickletRS232.PARITY_FORCED_PARITY_1 = 3
  • BrickletRS232.PARITY_FORCED_PARITY_0 = 4
  • BrickletRS232.STOPBITS_1 = 1
  • BrickletRS232.STOPBITS_2 = 2
  • BrickletRS232.WORDLENGTH_5 = 5
  • BrickletRS232.WORDLENGTH_6 = 6
  • BrickletRS232.WORDLENGTH_7 = 7
  • BrickletRS232.WORDLENGTH_8 = 8
  • BrickletRS232.HARDWARE_FLOWCONTROL_OFF = 0
  • BrickletRS232.HARDWARE_FLOWCONTROL_ON = 1
  • BrickletRS232.SOFTWARE_FLOWCONTROL_OFF = 0
  • BrickletRS232.SOFTWARE_FLOWCONTROL_ON = 1
Sub BrickletRS232.SetBreakCondition(ByVal breakTime As Integer)

Sets a break condition (the TX output is forced to a logic 0 state). The parameter sets the hold-time of the break condition (in ms).

New in version 2.0.2 (Plugin).

Advanced Functions

Function BrickletRS232.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 BrickletRS232.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 BrickletRS232.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:

  • BrickletRS232.FUNCTION_ENABLE_READ_CALLBACK = 3
  • BrickletRS232.FUNCTION_DISABLE_READ_CALLBACK = 4
  • BrickletRS232.FUNCTION_SET_CONFIGURATION = 6
  • BrickletRS232.FUNCTION_SET_BREAK_CONDITION = 10
Sub BrickletRS232.SetResponseExpectedAll(ByVal responseExpected As Boolean)

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

Sub BrickletRS232.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 BrickletRS232.EnableReadCallback()

Enables the ReadCallback callback.

By default the callback is disabled.

Sub BrickletRS232.DisableReadCallback()

Disables the ReadCallback callback.

By default the callback is disabled.

Function BrickletRS232.IsReadCallbackEnabled() As Boolean

Returns true if the ReadCallback callback is enabled, false otherwise.

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 BrickletRS232, ByVal value As Short)
    Console.WriteLine("Value: {0}", value)
End Sub

AddHandler rs232.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 BrickletRS232.ReadCallback(ByVal sender As BrickletRS232, ByVal message() As Char, ByVal length As Byte)

This callback is called if new data is available. The message has a maximum size of 60 characters. The actual length of the message is given in addition.

To enable this callback, use EnableReadCallback().

Event BrickletRS232.ErrorCallback(ByVal sender As BrickletRS232, ByVal error As Byte)

This callback is called if an error occurs. Possible errors are overrun, parity or framing error.

The following constants are available for this function:

  • BrickletRS232.ERROR_OVERRUN = 1
  • BrickletRS232.ERROR_PARITY = 2
  • BrickletRS232.ERROR_FRAMING = 4

New in version 2.0.1 (Plugin).

Constants

Const BrickletRS232.DEVICE_IDENTIFIER

This constant is used to identify a RS232 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 BrickletRS232.DEVICE_DISPLAY_NAME

This constant represents the human readable name of a RS232 Bricklet.