PCAN-UDS: Configuring Functional TesterPresent Guide

PCAN-UDS API 2.1.0 does not enable automatic TesterPresent by default for functional requests. Enable it by registering a custom session with PUDS_PARAMETER_SESSION_INFO and assigning functional Network Address Information (NAI).

Why Functional TesterPresent Requires a Custom Session

The documented physical-addressing setup does not automatically cover functional requests. For functional addressing, create an uds_sessioninfo structure, set its session and timing fields, configure its NAI as functional, and register it through UDS_SetValue_2013.

Configure the Functional Session

The following configuration was reported to enable automatic TesterPresent. The address and timing values belong to that configuration; verify them against the target ECU and network rather than treating them as universal defaults.

uds_sessioninfo new_sessioninfo;

new_sessioninfo.can_msg_type =
    cantp_can_msgtype.PCANTP_CAN_MSGTYPE_EXTENDED;
new_sessioninfo.session_type = 0x05;
new_sessioninfo.timeout_p2can_server_max = 50;
new_sessioninfo.timeout_enhanced_p2can_server_max = 500;
new_sessioninfo.s3_client_ms = 2000;

new_sessioninfo.nai.protocol =
    uds_msgprotocol.PUDS_MSGPROTOCOL_ISO_15765_2_29B_FIXED_NORMAL;
new_sessioninfo.nai.target_type =
    cantp_isotp_addressing.PCANTP_ISOTP_ADDRESSING_FUNCTIONAL;
new_sessioninfo.nai.source_addr = (UInt16)0xF1;
new_sessioninfo.nai.target_addr = (UInt16)0xFF;
new_sessioninfo.nai.extension_addr = 0;

status = UDS_SetValue_2013(
    tp_handle,
    PUDS_PARAMETER_SESSION_INFO,
    &new_sessioninfo,
    sizeof(uds_sessioninfo));

Register and Verify the Session

1. Adapt can_msg_type, session_type, timing fields, protocol, and NAI addresses to the actual diagnostic network.
2. Set new_sessioninfo.nai.target_type to PCANTP_ISOTP_ADDRESSING_FUNCTIONAL.
3. Call UDS_SetValue_2013 with PUDS_PARAMETER_SESSION_INFO and confirm that the returned status indicates success.
4. Verify on the diagnostic network that automatic TesterPresent traffic uses the configured functional addressing and the required s3_client_ms interval.

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