Delphi/Lazarus - RS232 Bricklet

This is the description of the Delphi/Lazarus 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 Delphi/Lazarus API bindings is part of their general description.

Examples

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

Loopback

Download (ExampleLoopback.pas)

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program ExampleLoopback;

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

{$ifdef MSWINDOWS}{$apptype CONSOLE}{$endif}
{$ifdef FPC}{$mode OBJFPC}{$H+}{$endif}

uses
  SysUtils, IPConnection, BrickletRS232;

type
  TExample = class
  private
    ipcon: TIPConnection;
    rs232: TBrickletRS232;
  public
    function StringToCharArray(const message_: string): TArray0To59OfChar;
    function CharArrayToString(const message_: TArray0To59OfChar; const length_: byte): string;
    procedure ReadCB(sender: TBrickletRS232; const message_: TArray0To59OfChar;
                     const length_: byte);
    procedure Execute;
  end;

const
  HOST = 'localhost';
  PORT = 4223;
  UID = 'XYZ'; { Change XYZ to the UID of your RS232 Bricklet }

var
  e: TExample;

{ Convert string to char array with length 60, as needed by write }
function TExample.StringToCharArray(const message_: string): TArray0To59OfChar;
var i: longint;
begin
  FillChar(result, 60, 0);
  for i := 1 to Length(message_) do begin
    result[i - 1] := message_[i];
  end;
end;

{ Assume that the message consists of ASCII characters and convert it from
  an array of chars to a string }
function TExample.CharArrayToString(const message_: TArray0To59OfChar; const length_: byte): string;
begin
  SetString(result, PChar(@message_[0]), length_);
end;

{ Callback procedure for read callback }
procedure TExample.ReadCB(sender: TBrickletRS232; const message_: TArray0To59OfChar;
                          const length_: byte);
begin
  WriteLn(Format('Message (Length: %d): "%s"', [length_, CharArrayToString(message_, length_)]));
end;

procedure TExample.Execute;
begin
  { Create IP connection }
  ipcon := TIPConnection.Create;

  { Create device object }
  rs232 := TBrickletRS232.Create(UID, ipcon);

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

  { Register read callback to procedure ReadCB }
  rs232.OnRead := {$ifdef FPC}@{$endif}ReadCB;

  { Enable read callback }
  rs232.EnableReadCallback;

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

  WriteLn('Press key to exit');
  ReadLn;
  ipcon.Destroy; { Calls ipcon.Disconnect internally }
end;

begin
  e := TExample.Create;
  e.Execute;
  e.Destroy;
end.

API

Since Delphi does not support multiple return values directly, we use the out keyword to return multiple values from a function.

All functions and procedures listed below are thread-safe.

Basic Functions

constructor TBrickletRS232.Create(const uid: string; ipcon: TIPConnection)

Creates an object with the unique device ID uid:

rs232 := TBrickletRS232.Create('YOUR_DEVICE_UID', ipcon);

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

function TBrickletRS232.Write(const message: array [0..59] of char; const length: byte): 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.

procedure TBrickletRS232.Read(out message: array [0..59] of char; out length: 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 OnRead callback.

procedure TBrickletRS232.SetConfiguration(const baudrate: byte; const parity: byte; const stopbits: byte; const wordlength: byte; const hardwareFlowcontrol: byte; const softwareFlowcontrol: 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:

  • BRICKLET_RS232_BAUDRATE_300 = 0
  • BRICKLET_RS232_BAUDRATE_600 = 1
  • BRICKLET_RS232_BAUDRATE_1200 = 2
  • BRICKLET_RS232_BAUDRATE_2400 = 3
  • BRICKLET_RS232_BAUDRATE_4800 = 4
  • BRICKLET_RS232_BAUDRATE_9600 = 5
  • BRICKLET_RS232_BAUDRATE_14400 = 6
  • BRICKLET_RS232_BAUDRATE_19200 = 7
  • BRICKLET_RS232_BAUDRATE_28800 = 8
  • BRICKLET_RS232_BAUDRATE_38400 = 9
  • BRICKLET_RS232_BAUDRATE_57600 = 10
  • BRICKLET_RS232_BAUDRATE_115200 = 11
  • BRICKLET_RS232_BAUDRATE_230400 = 12
  • BRICKLET_RS232_PARITY_NONE = 0
  • BRICKLET_RS232_PARITY_ODD = 1
  • BRICKLET_RS232_PARITY_EVEN = 2
  • BRICKLET_RS232_PARITY_FORCED_PARITY_1 = 3
  • BRICKLET_RS232_PARITY_FORCED_PARITY_0 = 4
  • BRICKLET_RS232_STOPBITS_1 = 1
  • BRICKLET_RS232_STOPBITS_2 = 2
  • BRICKLET_RS232_WORDLENGTH_5 = 5
  • BRICKLET_RS232_WORDLENGTH_6 = 6
  • BRICKLET_RS232_WORDLENGTH_7 = 7
  • BRICKLET_RS232_WORDLENGTH_8 = 8
  • BRICKLET_RS232_HARDWARE_FLOWCONTROL_OFF = 0
  • BRICKLET_RS232_HARDWARE_FLOWCONTROL_ON = 1
  • BRICKLET_RS232_SOFTWARE_FLOWCONTROL_OFF = 0
  • BRICKLET_RS232_SOFTWARE_FLOWCONTROL_ON = 1
procedure TBrickletRS232.GetConfiguration(out baudrate: byte; out parity: byte; out stopbits: byte; out wordlength: byte; out hardwareFlowcontrol: byte; out softwareFlowcontrol: byte)

Returns the configuration as set by SetConfiguration.

The following constants are available for this function:

  • BRICKLET_RS232_BAUDRATE_300 = 0
  • BRICKLET_RS232_BAUDRATE_600 = 1
  • BRICKLET_RS232_BAUDRATE_1200 = 2
  • BRICKLET_RS232_BAUDRATE_2400 = 3
  • BRICKLET_RS232_BAUDRATE_4800 = 4
  • BRICKLET_RS232_BAUDRATE_9600 = 5
  • BRICKLET_RS232_BAUDRATE_14400 = 6
  • BRICKLET_RS232_BAUDRATE_19200 = 7
  • BRICKLET_RS232_BAUDRATE_28800 = 8
  • BRICKLET_RS232_BAUDRATE_38400 = 9
  • BRICKLET_RS232_BAUDRATE_57600 = 10
  • BRICKLET_RS232_BAUDRATE_115200 = 11
  • BRICKLET_RS232_BAUDRATE_230400 = 12
  • BRICKLET_RS232_PARITY_NONE = 0
  • BRICKLET_RS232_PARITY_ODD = 1
  • BRICKLET_RS232_PARITY_EVEN = 2
  • BRICKLET_RS232_PARITY_FORCED_PARITY_1 = 3
  • BRICKLET_RS232_PARITY_FORCED_PARITY_0 = 4
  • BRICKLET_RS232_STOPBITS_1 = 1
  • BRICKLET_RS232_STOPBITS_2 = 2
  • BRICKLET_RS232_WORDLENGTH_5 = 5
  • BRICKLET_RS232_WORDLENGTH_6 = 6
  • BRICKLET_RS232_WORDLENGTH_7 = 7
  • BRICKLET_RS232_WORDLENGTH_8 = 8
  • BRICKLET_RS232_HARDWARE_FLOWCONTROL_OFF = 0
  • BRICKLET_RS232_HARDWARE_FLOWCONTROL_ON = 1
  • BRICKLET_RS232_SOFTWARE_FLOWCONTROL_OFF = 0
  • BRICKLET_RS232_SOFTWARE_FLOWCONTROL_ON = 1
procedure TBrickletRS232.SetBreakCondition(const breakTime: word)

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 TBrickletRS232.GetAPIVersion: array [0..2] of 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 TBrickletRS232.GetResponseExpected(const functionId: byte): 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.

procedure TBrickletRS232.SetResponseExpected(const functionId: byte; const responseExpected: 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:

  • BRICKLET_RS232_FUNCTION_ENABLE_READ_CALLBACK = 3
  • BRICKLET_RS232_FUNCTION_DISABLE_READ_CALLBACK = 4
  • BRICKLET_RS232_FUNCTION_SET_CONFIGURATION = 6
  • BRICKLET_RS232_FUNCTION_SET_BREAK_CONDITION = 10
procedure TBrickletRS232.SetResponseExpectedAll(const responseExpected: boolean)

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

procedure TBrickletRS232.GetIdentity(out uid: string; out connectedUid: string; out position: char; out hardwareVersion: array [0..2] of byte; out firmwareVersion: array [0..2] of byte; out deviceIdentifier: word)

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

procedure TBrickletRS232.EnableReadCallback

Enables the OnRead callback.

By default the callback is disabled.

procedure TBrickletRS232.DisableReadCallback

Disables the OnRead callback.

By default the callback is disabled.

function TBrickletRS232.IsReadCallbackEnabled: boolean

Returns true if the OnRead 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:

procedure TExample.MyCallback(sender: TBrickletRS232; const param: word);
begin
  WriteLn(param);
end;

rs232.OnExample := {$ifdef FPC}@{$endif}example.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.

property TBrickletRS232.OnRead
procedure(sender: TBrickletRS232; const message: array [0..59] of char; const length: byte) of object;

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.

property TBrickletRS232.OnError
procedure(sender: TBrickletRS232; const error: byte) of object;

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

The following constants are available for this function:

  • BRICKLET_RS232_ERROR_OVERRUN = 1
  • BRICKLET_RS232_ERROR_PARITY = 2
  • BRICKLET_RS232_ERROR_FRAMING = 4

New in version 2.0.1 (Plugin).

Constants

const BRICKLET_RS232_DEVICE_IDENTIFIER

This constant is used to identify a RS232 Bricklet.

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

const BRICKLET_RS232_DEVICE_DISPLAY_NAME

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