Detcon RXT-300 - Manual (Page 25)

RXT-300 SmartWireless™
RXT-300 Wireless IM Rev. 2.0 Page 19 of 41
3.4.3 Alarm Setup Summary
In summary, there are alarm events that are generated for multiple conditions around the system. For every
alarm event they can be either ignored or they can be mapped into one of four Alarm Outputs. Alarm Zones
provides additional mapping of these Alarm Outputs to specific groups of RXT-300s. Finally, the Alarm
Outputs on each RXT-300 have properties to configure the way the Alarm Outputs operate. Each of these
settings is part of the configuration that the user creates and stores in each RXT-300 of the system.
3.5 Network Sleep
In systems where batteries are used to power the different RXT-300 based Stations, the RXT-300 network can
be put to sleep after polling all RXT-300s in the network. In this way battery life can be extended since the
wireless radios consume most of the power on an RXT-300. If the user enables this feature, the Master
RXT-300 will poll all the RXT-300s on the network and then issue a sleep command. During sleep the
wireless radios are put in a low power state and no updates across the network will occur during this time. As
sleep time is increased battery life is extended but the time between data being updated is also increase. A
simplistic formula would be:
Sensor Data Update = Poll Cycle Time + Sleep Time
The Poll Cycle time will also increase as the number of devices and RXT-300s are added to the network.
NOTE: If Network Sleep is used to conserve battery life, there will be a tradeoff between
sleep time and real time updates of sensor data.
NOTE: Even though the network may be asleep, since all network data is updated and stored
locally within a RXT-300, external Modbus™ controllers can still poll this data continuously
as if the devices are still available. When the RXT-300s wake up this data will be updated to
the latest values.
Sleep can be disabled in systems where battery life is not an issue or if the RXT-300s are not battery powered.
With sleep disabled the sensor updates will occur faster and will equal the poll cycle time.
3.6 Network Control
There are multiple controls provided to allow a HMI Station or Modbus ™controller attached to a RXT-300 to
manage a RXT-300 system. These commands are Alarm Reset, Alarm Silence, Alarm Inhibit, Alarm Test and
RF Silence. An HMI Station or Modbus ™controller attached to a RXT-300 can use a Modbus™ write to
control registers on the RXT-300 to execute these commands. Once a command is given it is executed
immediately on that RXT-300 but if it is a Slave RXT-300 (not Master) there will be a delay until it is polled
and then the command is sent to the rest of the system. There is a network command status register that can be
monitored to determine when the command is sent to the rest of the network. The worst case delay from the
time the Modbus™ controller sends the command to the time it is executed across the whole network is equal
to the Poll Cycle Time + Sleep Time.
3.6.1 Alarm Reset and Alarm Silence
Alarm Reset and Alarm Silence are similar commands and will both de-active Alarm outputs on RXT-300s
depending on their configuration. The HMI Panel actually executes both commands simultaneously when an
Alarm Reset is executed. The following rules apply to whether an Alarm Output is de-activated for an Alarm
Reset or Silence: