Detcon RXT-300 - Manual (Page 22)

RXT-300 SmartWireless™
RXT-300 Wireless IM Rev. 2.0 Page 16 of 41
each poll a different RXT-300 is queried and will transmit its data stored locally to the rest of the RXT-300s
on the network. This continues until all RXT-300s are polled across the network. As part of the polling
process the Master RXT-300 will also transmit its own data to the network at the appropriate time.
The Master RXT-300 can be any one of the RXT-300s in the network but the “election” process can be guided
by the user when the RXT-300s are configured and set up. If a Master RXT-300 fails this will be detected by
all the other RXT-300s and a new Master RXT-300 will be elected. The network polling will continue after
the election is complete. This alleviates a single point of failure.
3.1 Station Configuration
For the RXT-300s to operate differently based upon the application they must be configured. This is done
with the RXT-300 Wireless Configuration Tool (WCT) and is covered in more detail in Section Error!
Reference source not found.. For purposes of this discussion it is sufficient to state that each RXT-300 in the
system is configured to perform a specific set of tasks. A single configuration file with all this information is
generated by the WCT and loaded wirelessly into the RXT-300s in the system. At power up the RXT-300s
will search through the configuration file and determine its own operation as well as what type of function it
will perform and whether it is a HMI Station, Sensor Station or an Alarm Station
3.2 HMI Station Operation
The RXT-300 RS-485 Modbus™ port can be configured to connect to a Modbus™ Master and allows the
Wireless HMI or a another Modbus™ controller to obtain status of the whole system. Since every RXT-300
maintains a complete status of the system much of this data has been made available for access through
Modbus™ registers on the RXT-300.
NOTE: An HMI Station/Modbus™ controller only monitors the network and does not
perform the actual polling of sensors and processing of alarms. It only provides the user a
visual status of the system and managing of alarms events such as alarm reset/inhibit/silence.
The RXT-300 will allow a direct access to sensor data as if it were directly attached to the controller through
Modbus™. The RXT-300 will perform a lookup based upon the sensor Modbus™ address/registers and
respond with data obtained from the network and stored locally. If the Modbus™ address/registers do not
match a configured sensor it will ignore the request or generate a Modbus™ exception.
If more than just sensor data is desired there are groups of registers that provide access to the status of each
RXT-300, network status and alarm status. There are additional registers that allow for sending commands
across the network. These commands are alarm reset, alarm silence, alarm inhibit, alarm test and RF silence.
Each RXT-300 in the system is assigned a unique Modbus™ address during configuration just like the sensors.
This address is used for all Modbus™ accesses.
The wireless HMI Panel has been designed to take advantage of all aspects RXT-300, both displaying sensor
status, alarms, RXT-300 status and network status. It also performs all control functions available. Another
great advantage is the HMI can read the RXT-300 configuration and automatically configure itself to display
everything about the system.
3.3 Sensor Station Operation
There are two ways sensors or devices can be attached to the RXT-300, using the Modbus™ interface and
using the 4-20mA interface. Sensors are added specific RXT-300s in the configuration along with the
Modbus™ address / registers and the alarm thresholds for each one. If a RXT-300 configured to have sensors
attached to either or both interfaces it will poll these sensors continuously and maintain a local copy of the data