docs(velodyne_monitor): add known limits (#1802)

* docs(velodyne_monitor): add known limits Signed-off-by: h-ohta <[email protected]> * Update Readme.md Signed-off-by: h-ohta <[email protected]>
autowarefoundation · Sep 7, 2022 · 1379811 · 1379811
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commit 1379811
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/system/velodyne_monitor/Readme.md b/system/velodyne_monitor/Readme.md
@@ -4,6 +4,8 @@
 
 This node monitors the status of Velodyne LiDARs.
 The result of the status is published as diagnostics.
+Take care not to use this diagnostics to decide the lidar error.
+Please read [Assumptions / Known limits](#assumptions--known-limits) for the detail reason.
 
 ## Inner-workings / Algorithms
 
@@ -75,4 +77,7 @@ Now, `VLP-16.param.yaml` is used as default argument because it is lowest spec.
 
 ## Assumptions / Known limits
 
-TBD.
+This node uses the [http_client](https://github.com/microsoft/cpprestsdk) and request results by GET method.
+It takes a few seconds to get results, or generate a timeout exception if it does not succeed the GET request.
+This occurs frequently and the diagnostics aggregator output STALE.
+Therefore I recommend to stop using this results to decide the lidar error, and only monitor it to confirm lidar status.