When retrieving event and alarm data using the Request Missing Data command, it is possible to fail to retrieve data for devices whose timestamp does not correspond to the timestamp of the event or alarm. For best results, follow the recommendations below when retrieving event and alarm data.
Each event and alarm data group has a “now” timestamp of the device at the point when the request was made. However the timestamp is often not from the device, as many devices don't return a timestamp, so the UIS will use its current time and adjust it for the time zone of the device. This can cause data retrieval problems when the timestamp of the device doesn't match the time of the event or alarm.
For example, if you request data through “now” (current time) and the UIS reports that “now” in Device time is 5:01 p.m., the FMS service will mark all events and alarms as received through 5:00 p.m. However, if the actual device thought it was 4:58 p.m. and then generated an event at 4:59 p.m., the Request Missing Data command would never retrieve that event because the next data request would start at 5:00 p.m.
The best way to avoid this situation is to do the following when retrieving event and alarm data.
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