The event log database in the sat-nms software stores device fault messages and other events. Each individual fault flag a device driver read from the device gets logged when it changes it's state. Beside this events like the start of the software, user logins or an NMS's communication connections to the VLCs are logged.
With device faults, not only the appearance of the fault is logged. Also the end of the fault state is logged by the device driver. The latter message also contains a note about the endurance of the fault state.
Event messages
Each message stored in the event log contains a time stamp, the message source, a message text and a priority value. The event priority tells about the importance of a event message.
The sat-nms software with it's factory settings does not use 'Alarm'. The operator however can configure the priority of each fault flag in the system to his needs. With a NMS system, event priorities have an impact to the event transport to the NMS (see below).
With a M&C system, the event log is stored at the M&C computer. The user interface software provides a ' Event Report Window ' which lets the operator query the event database and a Live Event Log Window which displays the recent events in a scrolling list.
The event database is limited in size. It implements a circular buffer which automatically purges all events older than a configurable limit. The factory setting for event log depth is 365 days. The M&C or NMS system administrator may change this by modifying a configuration file.
Collecting events in the NMS
With a sat-nms network management system, the event log at the NMS site centrally stored the messages originated from all VLCs in the network. Each particular VLC uses a temporary buffer to hold it's events messages until it is able to send them to the NMS. In this case the event log stores additional data with each event:
The event queue in the VLC
Each VLC contains an event queue which intermediately stores event messages until they are sent to the NMS. The ' System ' device which is present in each VLC controls the behavior of this queue. It is essential to configure the parameters of an VLCs event queue when the VLC is setup, event messages may be lost if they are left unconfigured. This also applies to a M&C system, here the event queue must explicitly must be switched off by setting 'localhost' as destination and all threshold values to zero.