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TCanSocket

A Lazarus component for convenient and easy-to-use access to CAN communication, using the SocketCAN functionality of the Linux kernel.

type TCanSocket = class(TComponent)
public
  function    Connect: Boolean;
  procedure   Disconnect; 
  function    Transmit(var Msg: TCanMsg): Boolean;
  function    FormatMsg(constref Msg: TCanMsg): string;
  property    Connected: Boolean;
  property    Devices: TCanDevices;
published
  property    Device: string;
  property    OnTransmitted: TCanMsgTransmittedEvent;
  property    OnReceived: TCanMsgReceivedEvent;
  property    OnErrorFrame: TCanErrFrameReceivedEvent;
  property    OnConnected: TCanConnectedEvent;
  property    OnDisconnected: TCanDisconnectedEvent;
end;

Properties

Name Description
Connected Read only boolean flag to determine if the CAN socket is in the connected state. True if connected. False otherwise.
Devices Provides access to the SocketCAN devices detected on the system. Devices.Count returns the total number of SocketCAN devices. Can also be indexed as array Devices[] to obtain the name of a SocketCAN device.
Device Name of the SocketCAN device to connect to. E.g. vcan0or can0. You can use property Devices to determine the names of the SocketCAN devices, currently available on the system.

Methods

Connect

function Connect: Boolean;

Connects the SocketCAN device to the CAN bus.

Return value
True if successfully connected, False otherwise.
Example - Connect to the first SocketCAN device detected on the system:
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procedure TForm1.BtnConnectClick(Sender: TObject);
begin
  // Set the SocketCAN device name to the first one detected on the system.
  CanSocket1.Device := CanSocket1.Devices[0];
  // Attempt to connect to the SocketCAN device.
  if CanSocket1.Connect then
    MessageDlg('Info', 'Successfully connected', mtInformation, [mbOk], 0)
  else
    MessageDlg('Error', 'Could not connect', mtError, [mbOk], 0);
end;

Disconnect

procedure Disconnect;

Disconnects the device from the CAN bus.

Transmit

function Transmit(var Msg: TCanMsg): Boolean;

Submits a CAN message for transmission. Note that this function writes the timestamp into the Msg parameter.

Parameter Description
Msg Message to transmit.
Return value
True if the message was successfully submitted for transmission, False otherwise.
Example - Transmit a CAN message:
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procedure TForm1.BtnTransmitClick(Sender: TObject);
var
  TxMsg: TCanMsg;
begin
  TxMsg.Id := $123;        // Set the CAN message identifier
  TxMsg.Ext := False;      // Set the identifier type to 11-bit
  TxMsg.Flags.Fd := False; // Configure the message as CAN classic
  TxMsg.Len := 2;          // Set the data length to 2 bytes
  TxMsg.Data[0] := $37;    // Set the value of data byte 0
  TxMsg.Data[1] := $A5;    // Set the value of data byte 1

  // Attempt to submit the CAN message for transmission
  if CanSocket1.Transmit(TxMsg) then
    MessageDlg('Info', 'Successfully transmitted', mtInformation, [mbOk], 0)
end;

FormatMsg

function FormatMsg(constref Msg: TCanMsg): string;

Converts a CAN message to a string.

Parameter Description
Msg CAN message to format as a string.
Return value
The CAN message formated as a string
Example - Display received CAN messages in a TMemo:
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procedure TForm1.CanSocket1Received(Sender: TObject; constref Msg: TCanMsg);
var
  MsgStr: string;
begin
  // Convert the newly received message to a string.
  MsgStr := CanSocket1.FormatMsg(Msg);
  // Add the string to the memo.
  Memo1.Lines.Add(MsgStr);
end;

Events

OnConnected

property OnConnected: TCanConnectedEvent;

Event handler that gets called after successfully connecting to the CAN device. Triggered by the Connect method.

Example - OnConnected event handler:
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procedure TForm1.CanSocket1Connected(Sender: TObject);
begin
  MessageDlg('Info', 'Successfully connected', mtInformation, [mbOk], 0)
end;

OnDisconnected

property OnDisconnected: TCanDisconnectedEvent;

Event handler that gets called after disconnecting from the CAN device. Triggered by the Disconnect method.

Example - OnDisconnected event handler:
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procedure TForm1.CanSocket1Disconnected(Sender: TObject);
begin
  MessageDlg('Info', 'Disconnected from CAN device', mtInformation, [mbOk], 0)
end;

OnReceived

property OnReceived: TCanMsgReceivedEvent;

Event handler that gets called upon reception of a CAN message.

Parameter Description
Msg Received CAN message.
Example - OnReceived event handler:
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procedure TForm1.CanSocket1Received(Sender: TObject; constref Msg: TCanMsg);
var
  InfoStr: string;
begin
  InfoStr := Format('Received CAN message with ID %xh', [Msg.Id]);
  MessageDlg('Info', InfoStr, mtInformation, [mbOk], 0)
end;

OnTransmitted

property OnTransmitted: TCanMsgTransmittedEvent;

Event handler that gets called once a CAN message was successfully submitted for transmission. Triggered by method Transmit.

Parameter Description
Msg Transmitted CAN message.
Example - OnTransmitted event handler:
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procedure TForm1.CanSocket1Transmitted(Sender: TObject; constref Msg: TCanMsg);
var
  InfoStr: string;
begin
  InfoStr := Format('Transmitted CAN message with ID %xh', [Msg.Id]);
  MessageDlg('Info', InfoStr, mtInformation, [mbOk], 0)
end;

OnErrorFrame

property OnErrorFrame: TCanErrFrameReceivedEvent;

Event handler that gets called upon reception of an error frame.

Example - OnErrorFrame event handler:
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procedure TForm1.CanSocket1ErrorFrame(Sender: TObject);
begin
  MessageDlg('Info', 'Error frame received', mtInformation, [mbOk], 0);
end;