Reporting alarms

Alarms transmit via an alarm message or read message depending on whether they are in a Walk-by/Drive-by or Fixed-Base system.

Walk-by/Drive-by

If the SmartPoint module is in Walk-by/Drive-by mode, alarms report through a read message. The Walk-by/Drive-by read message contains the current reading and indicator of which latching alarms are being reported.

If the current reading is unknown, the SmartPoint module sends an alarm message instead of the Walk-by/Drive-by reading message. The reading value is set to zero.

Fixed-Base

If the SmartPoint module is in fixed-base mode (AMI), alarms report through an alarm message.

The alarm message contains a field "time since event" that indicates the elapsed time since an alarm condition was detected or the endpoint was reset. When a small value is observed in the time since event field, the alarm message indicates the detection of a new alarm condition. When multiple alarms conditions are reported there is no indication of which alarm is the most recent. However, by observing the sequence of alarm messages and time since event fields, it is possible to reconstruct the sequence and age of each alarm condition.

Alarm messages are transmitted for four reasons:
  1. A new alarm condition occurs for the first time. Alarm detection always takes place at the Meter Sample Rate. When the SmartPoint module detects a new alarm condition, it immediately transmits two alarm messages. These messages will be spaced 8 seconds apart.
  2. The SmartPoint module reboots. When it reboots, it transmits the same alarm condition message a minimum of three times to the RNI.
  3. Weekly Status. The SmartPoint module transmits one alarm message per week (dithered) as a status report. The alarm message sends even in the absence of any detected alarm conditions.
  4. Unsuccessful reading. When it is time to transmit a scheduled reading, if the reading value is unsuccessful, an alarm message transmits in lieu of the reading message.