struct ara::tsync::TimeSlaveMeasurementType

The structure is used to capture and provide detailed measurement and protocol data for the continuous validation of the synchronization behavior of a Time Slave [SWS_TS_14156]. For this purpose, it bundles external timestamps and correction values of received synchronization messages with the currently valid path delay value and local reference timestamps [SWS_TS_14155]. As a passive data object, the type has no control logic of its own and is likely instantiated per synchronization cycle and passed to higher-level analysis components for plausibility checks. Question (open)

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Context

The structure ara::tsync::TimeSlaveMeasurementType is used within the Time Synchronization Functional Cluster (tsync) to provide detailed measurement data for validating a Time Slave. In the context of time-synchronized communication in distributed AUTOSAR systems, safeguarding timing accuracy requires reliable verification of the synchronization steps. The structure functions here as a standardized data container aggregating protocol-relevant measurement values of a synchronization cycle.

Essentially three components participate in the interaction: an external Time Master, the receiving Time Slave, and a downstream validation or diagnostic entity. The Time Slave receives synchronization messages from the master and extracts protocol-specific parameters from them, such as the sequence number sequenceId [SWS_TS_14156] of the sync frame as well as the correction value correctionField [SWS_TS_14153] and the transmission timestamp preciseOriginTimestamp [SWS_TS_14150] from the associated follow-up frame. Augmented with local timestamps and the current path delay value pDelay [SWS_TS_14155], the Time Slave provides this data to the validation entity to assess synchronization quality.

Lifecycle

As a pure data container (struct ... final), ara::tsync::TimeSlaveMeasurementType possesses no state machine of its own and no active lifecycle phases. Instances are likely instantiated as ephemeral value objects on the stack or in internal buffers as soon as a matching pair of sync and follow-up frames has been processed by the Time Slave. Question Q-d6401d9eff1764d3 (open) During this initialization phase, all attributes—including the reference timestamps for the global part referenceGlobalTimestamp [SWS_TS_14151] and the virtual local part referenceLocalTimestamp [SWS_TS_14154] as well as the ingress timestamp syncIngressTimestamp [SWS_TS_14152]—are consistently populated.

After population, the object is passed to the evaluating validation logic. Since the structure does not contain any synchronization mechanisms for concurrent access, applications must ensure external synchronization or pass-by-copy when transferring across threads. Once the check of the synchronization parameters is complete, the object's lifetime ends through regular deallocation of memory.

Usage Path

The regular sequence for capturing and providing the measurement data follows the sequence of the synchronization protocol:

1. Reception of the sync frame: Upon arrival of the synchronization frame, the Time Slave captures the arrival time in virtual local time as syncIngressTimestamp [SWS_TS_14152] and adopts the sequenceId [SWS_TS_14156].
2. Reception of the follow-up frame: The transmission timestamp preciseOriginTimestamp [SWS_TS_14150] and the correction field correctionField [SWS_TS_14153] are read from the subsequent message.
3. Consolidation of local parameters: The Time Slave adds the currently determined propagation delay value pDelay [SWS_TS_14155] and the time tuple consisting of referenceGlobalTimestamp [SWS_TS_14151] and referenceLocalTimestamp [SWS_TS_14154] to the structure.
4. Handover for validation: The consolidated structure is transmitted to the validation entity, which checks the data for discrepancies.

Sequence diagram: Sequence of measurement data acquisition at the Time Slave for validation. Sources: [SWS_TS_14150], [SWS_TS_14152], [SWS_TS_14153], [SWS_TS_14156].

Error Scenarios

Since ara::tsync::TimeSlaveMeasurementType represents a passive data structure without methods, it does not throw exceptions itself and does not report error codes. Error conditions manifest indirectly via the plausibility of the contained values:

• Lost frames or misordering: A gap or jump in the sequenceId [SWS_TS_14156] indicates dropped frames or runtime issues on the transmission medium.
• Stale or invalid path delay: An implausible or missing value in pDelay [SWS_TS_14155] leads to calculation errors during propagation delay compensation.
• Discrepancies in timestamps: Inconsistencies between syncIngressTimestamp [SWS_TS_14152] and the local tuple consisting of referenceGlobalTimestamp [SWS_TS_14151] and referenceLocalTimestamp [SWS_TS_14154] indicate synchronization errors or drift of the local clock.

Evaluating entities must therefore check the data structure for completeness and plausibility before processing it further.