can bus - How to send the Diagnostic IDs (DIDs) through CAPL script?

Can bus - How to send the Diagnostic IDs (DIDs) through CAPL script?

In automotive systems, the Controller Area Network (CAN) bus allows for communication between different electronic control units (ECUs). Diagnostic IDs (DIDs) are a fundamental part of On-Board Diagnostics (OBD) and Unified Diagnostic Services (UDS), providing a way to request and respond to diagnostic data.

To send Diagnostic IDs (DIDs) over CAN in a CAPL (Communication Access Programming Language) script, you need to construct a CAN message that follows the UDS protocol format. CAPL is used with CANoe and CANalyzer for testing, simulation, and diagnostics in automotive networks.

Here is a step-by-step guide on how to send a diagnostic request using a CAPL script.

Step 1: Understand the UDS Protocol

UDS is a protocol used in automotive diagnostics over CAN. Diagnostic requests are sent as CAN frames with specific structure:

  • Service Identifier (SID): Defines the type of diagnostic service (e.g., 0x10 for Diagnostic Session Control).
  • Data: Additional data for the service.

Diagnostic IDs (DIDs) are part of specific services, like Read Data By Identifier (0x22), Write Data By Identifier (0x2E), etc.

Step 2: Construct the CAN Frame in CAPL

To send a UDS request, you must create a CAN frame with the appropriate ID, SID, and DID. Here's an example that sends a Read Data By Identifier request (0x22) for a specific DID.

variables { message 0x7DF reqMsg; // Example CAN ID for sending } on key 'r' { // Send the request when 'r' key is pressed // Set CAN ID and DLC reqMsg.id = 0x7DF; // Change to appropriate CAN ID reqMsg.dlc = 3; // Data Length Code, depending on the service // Set service identifier and DID reqMsg.byte(0) = 0x22; // SID for Read Data By Identifier reqMsg.byte(1) = 0x01; // High byte of DID (0x0101 in this example) reqMsg.byte(2) = 0x01; // Low byte of DID // Send the message output(reqMsg); } on message 0x7E8 { // Example CAN ID for the response message msg = _msg; // Capture the message data // Handle the response write("Received response: %x", msg.byte(0)); // Process the response }

Explanation

  • Variables Section: Declare the CAN message reqMsg with an ID of 0x7DF. This ID may vary depending on your application.
  • on key Event: Triggers when a specific key is pressed (in this case, 'r'). This is used to simulate sending the diagnostic request.
  • Constructing the Request: Set the CAN ID and data length code (DLC). Add the service identifier and DID (for example, Read Data By Identifier with DID 0x0101).
  • Sending the Message: Use output(reqMsg) to send the CAN frame.
  • Handling Responses: Define an on message event to process the response from the ECU. The CAN ID for the response may differ, depending on your setup.

Additional Considerations

  • CAN IDs and DLC: Ensure that the CAN ID and DLC are appropriate for your system. Adjust these values according to your setup.
  • Service Identifiers and DIDs: Familiarize yourself with the UDS specification to understand the correct SIDs and DIDs for different diagnostic operations.
  • Tools and Simulations: When using CAPL scripts in tools like CANoe or CANalyzer, test thoroughly to ensure the correct behavior.

By following these steps, you can send Diagnostic IDs (DIDs) over CAN using CAPL scripts, allowing you to perform a range of diagnostic operations in automotive systems.

Examples

  1. "CAPL script to send CAN message with Diagnostic ID (DID)"

    • This query aims to send a specific CAN message with a predefined DID. Here's a CAPL script that sends a diagnostic request with a custom DID.
    variables { message 0x7DF msgReq; // Example CAN ID for diagnostic request } on start { msgReq.len = 8; // 8-byte CAN message msgReq.byte(0) = 0x03; // Number of data bytes msgReq.byte(1) = 0x22; // Service type: ReadDataByIdentifier msgReq.byte(2) = 0x01; // High byte of DID msgReq.byte(3) = 0x02; // Low byte of DID output(msgReq); }

  2. "CAPL script to send diagnostic request to specific CAN ID"

    • This query helps create a script that sends a diagnostic request to a specific CAN ID, typically for testing.
    variables { message 0x7E0 msgReq; // Specified diagnostic CAN ID } on start { msgReq.len = 3; // 3-byte CAN message msgReq.byte(0) = 0x02; // Number of data bytes msgReq.byte(1) = 0x10; // Example diagnostic service msgReq.byte(2) = 0x03; // Additional service parameter output(msgReq); }

  3. "CAPL script to set custom CAN ID for diagnostic messages"

    • This query helps set a custom CAN ID for sending diagnostic messages.
    variables { message myDiagnosticMessage; } on start { myDiagnosticMessage.id = 0x123; // Set custom CAN ID myDiagnosticMessage.len = 8; // Length of the CAN message myDiagnosticMessage.byte(0) = 0x01; // Data for the diagnostic message // Rest of the data as needed output(myDiagnosticMessage); }

  4. "How to send multiple diagnostic requests through CAPL"

    • This script demonstrates sending multiple diagnostic requests with various DIDs.
    variables { message 0x7DF msgReq; } on start { msgReq.len = 8; // Sending first diagnostic request msgReq.byte(0) = 0x03; msgReq.byte(1) = 0x22; msgReq.byte(2) = 0x01; msgReq.byte(3) = 0x03; output(msgReq); // Delay between requests wait(200); // Sending second diagnostic request msgReq.byte(3) = 0x04; // Changing the DID output(msgReq); }

  5. "CAPL script to receive diagnostic response"

    • This query focuses on handling a diagnostic response after sending a request.
    variables { message 0x7E8 response; // Expected response CAN ID } on message response { write("Received diagnostic response: ", response.byte(0)); }

  6. "CAPL script to send specific diagnostic service request"

    • This query is for sending a specific diagnostic service request, like reading error codes.
    variables { message 0x7E0 msgReq; } on start { msgReq.len = 2; // Length for service request msgReq.byte(0) = 0x01; // Service type: ReadErrorCodes msgReq.byte(1) = 0x03; // Example service parameter output(msgReq); }

  7. "CAPL script to send diagnostic data at regular intervals"

    • This script sends diagnostic data at regular intervals using a timer.
    variables { message 0x7E0 msgReq; timer myTimer = 1000; // Set interval to 1000 ms } on start { setTimer(myTimer, 1000); // Start the timer } on timer myTimer { msgReq.len = 8; msgReq.byte(0) = 0x03; // Data bytes msgReq.byte(1) = 0x22; // Diagnostic service type msgReq.byte(2) = 0x01; // Example DID high byte msgReq.byte(3) = 0x05; // Example DID low byte output(msgReq); setTimer(myTimer, 1000); // Reset the timer }

  8. "CAPL script to send diagnostic request with varying data length"

    • This query is useful for sending diagnostic requests with varying data lengths.
    variables { message 0x7DF msgReq; } on start { msgReq.len = 3; // Example length msgReq.byte(0) = 0x03; // Number of data bytes msgReq.byte(1) = 0x22; // Service type msgReq.byte(2) = 0x06; // Data output(msgReq); wait(500); // Change data length msgReq.len = 5; msgReq.byte(3) = 0x07; msgReq.byte(4) = 0x08; output(msgReq); }

  9. "CAPL script to simulate ECU diagnostic communication"

    • This script simulates communication with an ECU for diagnostic purposes.
    variables { message 0x7E0 msgReq; } on start { msgReq.len = 8; msgReq.byte(0) = 0x03; // Data bytes msgReq.byte(1) = 0x22; // Diagnostic service type msgReq.byte(2) = 0x10; // Example data msgReq.byte(3) = 0x20; // Additional data output(msgReq); } on message 0x7E1 { write("Received response from ECU:", this.byte(0)); }

  10. "CAPL script to send diagnostic request with conditional checks"

    • This query adds conditional checks before sending diagnostic requests.
    variables { message 0x7DF msgReq; bool sendFlag = true; // Example condition } on start { if (sendFlag) // Conditional check { msgReq.len = 8; msgReq.byte(0) = 0x03; // Number of data bytes msgReq.byte(1) = 0x22; // Diagnostic service msgReq.byte(2) = 0x30; // Example data msgReq.byte(3) = 0x40; // Additional data output(msgReq); } }

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