| Range | Category | Examples |
|---|---|---|
| 0xF100–0xF17F | Vehicle manufacturer data | VIN (0xF190), ECU hardware version (0xF191), SW version (0xF189) |
| 0xF180–0xF1FF | ISO/SAE reserved vehicle information | Boot SW ID (0xF180), App SW Fingerprint (0xF184) |
| 0x0100–0xEFFF | Vehicle manufacturer specific | Calibration data, sensor readings, application state variables |
| 0xF200–0xF2FF | Periodic DID (for 0x2A service) | Same as above but scheduled for periodic transmission |
| 0x0000–0x00FF | ISO/SAE reserved | Do not use in OEM implementation |
DID Categories and Standardised Ranges
AUTOSAR DCM: ReadDataByIdentifier Implementation
CDcm_Did0xF190.c
/* AUTOSAR DCM callback: ReadDataByIdentifier for VIN (DID 0xF190) */
/* Generated skeleton by DaVinci/EB tresos; implement in application layer */
#include "Dcm.h"
#include "NvM.h"
/* DCM calls this function when 0x22 0xF1 0x90 is received */
Std_ReturnType DcmDspData_VIN_ReadData(Dcm_OpStatusType OpStatus,
uint8* Data,
Dcm_NegativeResponseCodeType* ErrorCode)
{
Std_ReturnType ret = E_OK;
if (OpStatus == DCM_INITIAL) {
/* Read VIN from NvM block */
ret = NvM_ReadBlock(NVM_BLOCK_VIN, Data);
if (ret != E_OK) {
*ErrorCode = DCM_E_CONDITIONSNOTCORRECT; /* NRC 0x22 */
return E_NOT_OK;
}
/* VIN is 17 bytes ASCII; DID response = 17 bytes */
return E_OK;
}
return E_NOT_OK; /* unexpected OpStatus */
}
/* ARXML configuration excerpt:
0xF190
17 (bytes)
USE_DATA_SYNCH_CLIENT_SERVER
DcmDspData_VIN_ReadData
DefaultSession
ExtendedDiagnosticSession
*/Multi-DID Request (ISO 14229-1:2020)
Multi-DID Request: Single 0x22 Frame, Multiple Responses
Request (tester → ECU):
0x22 0xF1 0x90 0xF1 0x89 0xF1 0x91
SID DID1_hi DID1_lo DID2_hi DID2_lo DID3_hi DID3_lo
(reads VIN + SW version + calibration fingerprint in one request)
Positive response (ECU → tester):
0x62 0xF1 0x90 [17 bytes VIN] 0xF1 0x89 [4 bytes SW ver] 0xF1 0x91 [4 bytes cal]
Each DID echoed before its data; total length determines frame count
Rules:
• ECU responds with all supported DIDs concatenated in order requested
• If any DID is not supported: NRC 0x31 (requestOutOfRange) for that DID
• If any DID requires higher security: NRC 0x33 for that DID
• Multi-DID uses same SID 0x22; no sub-function byte
• Max request length limited by CanTp (4095 bytes classic CAN)
→ max ~1365 DIDs per request (each 3 bytes); practical limit: ≤ 20 DIDsDID Design Best Practices
| Practice | Rationale |
|---|---|
| Reserve 0xF180–0xF18F for standardised boot/app SW identification DIDs | Required for OBD-II compliance and workshop tool compatibility |
| Keep diagnostic DID data <= 7 bytes when possible | Avoids multi-frame overhead; faster reads in production test |
| Document DID byte order explicitly in CDD (big-endian default) | Endianness bugs cause hard-to-diagnose scaling errors in tester |
| Group related data in one DID rather than many small DIDs | Reduces request/response round trips; one 0x22 vs ten 0x22 calls |
| Include a DID version counter in long DIDs | Allows backward-compatible extensions without breaking existing testers |
Summary
DID 0xF190 (VIN) and 0xF189 (SW version) are the two most commonly read identifiers — every workshop tool reads them first. The AUTOSAR DCM callback must return E_OK synchronously or initiate an asynchronous operation with DCM_E_PENDING; blocking inside the callback stalls the DCM and blocks all other diagnostic services. Multi-DID requests reduce round-trip count for production EOL testing — a single 0x22 with 10 DIDs is far faster than 10 sequential reads, especially over CAN where each round trip is 50+ ms.
🔬 Deep Dive — Core Concepts Expanded
This section builds on the foundational concepts covered above with additional technical depth, edge cases, and configuration nuances that separate competent engineers from experts. When working on production ECU projects, the details covered here are the ones most commonly responsible for integration delays and late-phase defects.
Key principles to reinforce:
- Configuration over coding: In AUTOSAR and automotive middleware environments, correctness is largely determined by ARXML configuration, not application code. A correctly implemented algorithm can produce wrong results due to a single misconfigured parameter.
- Traceability as a first-class concern: Every configuration decision should be traceable to a requirement, safety goal, or architecture decision. Undocumented configuration choices are a common source of regression defects when ECUs are updated.
- Cross-module dependencies: In tightly integrated automotive software stacks, changing one module's configuration often requires corresponding updates in dependent modules. Always perform a dependency impact analysis before submitting configuration changes.
🏭 How This Topic Appears in Production Projects
- Project integration phase: The concepts covered in this lesson are most commonly encountered during ECU integration testing — when multiple software components from different teams are combined for the first time. Issues that were invisible in unit tests frequently surface at this stage.
- Supplier/OEM interface: This is a topic that frequently appears in technical discussions between Tier-1 ECU suppliers and OEM system integrators. Engineers who can speak fluently about these details earn credibility and are often brought into critical design review meetings.
- Automotive tool ecosystem: Vector CANoe/CANalyzer, dSPACE tools, and ETAS INCA are the standard tools used to validate and measure the correct behaviour of the systems described in this lesson. Familiarity with these tools alongside the conceptual knowledge dramatically accelerates debugging in real projects.
⚠️ Common Mistakes and How to Avoid Them
- Assuming default configuration is correct: Automotive software tools ship with default configurations that are designed to compile and link, not to meet project-specific requirements. Every configuration parameter needs to be consciously set. 'It compiled' is not the same as 'it is correctly configured'.
- Skipping documentation of configuration rationale: In a 3-year ECU project with team turnover, undocumented configuration choices become tribal knowledge that disappears when engineers leave. Document why a parameter is set to a specific value, not just what it is set to.
- Testing only the happy path: Automotive ECUs must behave correctly under fault conditions, voltage variations, and communication errors. Always test the error handling paths as rigorously as the nominal operation. Many production escapes originate in untested error branches.
- Version mismatches between teams: In a multi-team project, the BSW team, SWC team, and system integration team may use different versions of the same ARXML file. Version management of all ARXML files in a shared repository is mandatory, not optional.
📊 Industry Note
Engineers who master both the theoretical concepts and the practical toolchain skills covered in this course are among the most sought-after professionals in the automotive software industry. The combination of AUTOSAR standards knowledge, safety engineering understanding, and hands-on configuration experience commands premium salaries at OEMs and Tier-1 suppliers globally.