Detcon RXT-320 - Manual (Page 6)

RXT-320 Wireless Modbus ™
RXT-320 Wireless IM Rev. 2.1 Page 2 of 27
information back to the master unit’s transceiver, which then places that information on the bus for the master
unit.
Modbus Slave
Devices
Modbus Master
Control Unit
Remote Monitor
Unit
Model X40-N4X
Muiti-Channel Gas Detection Control System
PGM 2
detcon inc.
H2 S S ensor
d etcon inc. MODEL
IR-700
Z ERO P GM1 SP A N
Figure 2 Typical Wireless Layout
The transceiver provides for the following features/connectivity:
 Modbus™ Interface:
Master or Slave connection for up to 32 Modbus™ devices on the network
 Wireless Radio:
IEEE 802.15.4, Mesh Topology, 16 RF channels, DSSS encoding, 2.4GHz
 4-20mA Inputs:
Two inputs available to connect two 4-20mA sensors/devices
 Alarm Outputs:
4 low current outputs capable of driving relays for audible/visual alarms
 Battery Operation:
Low Power Sleep and battery life available from Detcon Smart Battery Pack
 Addressable:
For Modbus™ access to RXT-320 control and status (set through term board)
 Multiple Modes:
Operational mode (Transparent, Master, Slave, Alarm Station) based on
address configuration
1.2 RXT-320 Wireless Radio
The RXT-320 transceivers utilize radios based upon the IEEE 802.15.4 standard that operate at 2.4 GHz using
DSSS encoding for robustness. DSSS was initially used by the military to resist jamming but later was widely
adopted for wireless implementations since it was robust in noisy environments. DSSS transmits data across a
wider frequency range than the actual frequency range required for the information. This operation minimizes
cross talk and interference from other transceivers and is less susceptible to noise from other sources.
The IEEE 802.15.4 defines 16 separate RF Channels that can be used in the 2.4 GHz range. The default
channel is 1 but can be change if there is RF interference or if there is an existing network using that channel.
Transceivers will only respond to other transceivers with the same RF Channel.