XLINK 500/100 Operations & Maintenance Manual page # 96
The station can be set up to send transmissions when it goes into alarm. Alternatively, the station
can be set up to make a transmission when it goes into alarm
and
to make another transmission
when it goes out of alarm.
All enabled transmissions of the Alarm kind will trigger with alarms.
The system can control its digital output based on alarm conditions. See the
section for details.
Most sensor readings cause alarms at the time the measurement is scheduled. If a temperature
sensor is set up for alarms with a
Measurement Interval
of 15 minutes, the station will read the
sensor every 15 minutes and decide whether to go into alarms.
Some sensors, including the tipping bucket and sensors setup as digital counter and level, can
cause instant alarms. When the tipping bucket tips, the system is immediately notified. If the tip
causes an alarm condition, the station goes into alarms right away, even if it was not time to
make a measurement.
Each measurement may be set up with up to three different alarms. This way, it is possible to get
an alarm when the stage reaches 3 feet, another alarm when it reaches 4 feet, and a third alarm
when it reaches 6 feet.
If more than three alarms are needed for one sensor, set up two measurements to read the same
sensor, but give them different alarm conditions.
9.5.1.
Alarm 1, Alarm 2, and Alarm 3
Each of these settings can have one of the following values
Off
High
Low
ROC
These settings are used to determine what kind of computation is made when checking a sensor
for alarms. Read on for a complete explanation.
9.5.2.
Threshold 1, Threshold 2, and Threshold 3
The threshold is a value that is compared to the sensor reading in order to determine whether to
go into or out of alarms.
9.5.3.
Deadband
The
Deadband,
along with the
Threshold
value is used to compute whether the measurement
will go
out of
alarms
. Deadband helps the system ignore noise on the input that would cause the
measurement to go in and out of alarm on each measurement.
For example, if a High Alarm with a the Threshold of 10.5 and a Deadband of 3.0 were setup, the
system would go into alarm once the reading was equal to or greater than 10.5. The system
would stay in alarms as long as the reading was equal to or greater than 7.5. Once the reading
dropped below 7.5, the system would go out of alarms.
9.5.4.
Alarm Tx Mode
Alarm Tx Mode
determines whether transmissions are made when the station goes (into alarm)
or (when it goes into
and
out of alarm).
