Topic Statistics: Interpret Missing Timestamp Evidence
Distinguish unavailable age measurements, incomplete arrival pairs and unsupported metrics when reviewing robot topic-statistics output. This guide concerns robot integration and delivery review. The proposed observations are editorial assessment guidance, grounded in the linked original documentation and subject to the deployed version. They do not describe an on-site test of a particular machine or establish whole-system acceptance from a single interface response.
Name the missing metric
Separate age, arrival period, message counts and any other monitoring fields. The referenced ROS 2 feature describes particular metrics rather than every communication measurement a dashboard might display. Establish the computation and implementation behind the empty field before interpreting it as evidence that the publisher stopped or the sensor failed.
For this review, identify the delivered device, software and configuration revisions first. Record unsupported, disabled and untested capabilities separately. Evidence from another model is useful context, but cannot establish what the delivered combination actually provides. Keep the original input beside the settings used to interpret it.
Check the header needed for age
Age needs a usable message timestamp. Continuing reception does not create that timestamp if the message type or producer does not supply it. Retain the message definition and an actual sample, checking field presence and population. Inserting an arbitrary current time to populate a chart would change the meaning of the measurement.
Retain the original input and the reason for the decision, rather than a successful screenshot alone. Change only the variables agreed for the comparison, and keep the before-and-after configuration. List conditions that were not exercised explicitly; they should not silently become part of the accepted operating range.
Keep zero separate from unavailable
Give valid zero, no sample yet and unsupported calculation distinct representations. Zero remains a value with meaning, rather than a universal placeholder. Preserve the raw statistic and display conversion rules. Exporting every empty field as zero can make a report appear to claim zero delay where no such observation was possible.
Use the three illustrated observations as starting questions, rather than as diagnoses of an installation that has not been inspected. Check record completeness, units and identity before selecting the next observation. An unresolved result is more informative than a confident explanation assembled from missing fields or unrelated test runs.
Inspect arrivals for period measurements
Period calculation concerns consecutive arrivals and therefore needs enough observations to form an interval. Review counts and collection state around startup or subscription interruptions. An unavailable age does not by itself establish an unavailable period. Check the deployed client library and version rather than assuming every implementation exposes the same monitoring capabilities.
Let the site owner choose an approved isolated way to exercise relevant exceptions. Record normal operation, the exceptional condition and recovery separately. The purpose is to establish how the application recognises and explains untrustworthy input, without requiring production equipment to act on deliberately invalid results.
Deliver the missing-evidence boundary
Record each metric’s source, prerequisites and unavailability reason, alongside independent reception evidence. If the application requires age but the interface supplies no suitable timestamp, identify the design gap. A period statistic may still be useful, but relabelling it as age would hide the missing information instead of resolving it.
Deliver the configuration, representative samples, result table and unresolved questions together. Agree who reviews subsequent changes. The receiving team should be able to select one conclusion and trace it back to its input and decision path without relying on the original author to reconstruct the missing steps.
Original documentation and further reading
Continue with related articles in this section, or use selection guides to prepare the next review. Apply the device-specific documentation and agreed operating conditions when implementing a test.