32
• Fewerpowersources�
Disadvantages:
• Largerpowersourcewillbeneeded
• Ifapowersourcefails,severalmonitoringpointsfail�
Multiple Transmitters Connected in a “Daisy-Chain”
Conguration
Thiscongurationconsistsoftwoormoretransmittersinstalled
inaline�Thepowerconnectionsareinstalledasanextensionof
theprevioustransmitter,withthersttransmitterbeingtheonly
oneactuallywiredtothepowersource�
Class 2
Power Supply
Figure 31. Daisy-chained transmitters from one power supply
Advantages:
• Lesswireneededforinstallation
• Fewerpowersources�
Disadvantages:
• Requiresalargerpowersource
• Shorterdistancebetweenpowersourceandtransmitters�
• Ifapowersourcefails,severalmonitoringpointsfail�
Note: CSA/FMcertificationdoesnotcoverdaisy-chainedXNXcombus-
tiblegastransmitters.
Power Source Selection
Foreachtypeofinstallation,selectionofpowersupplyis
important�Powersuppliesareratedbyvoltageandpower�
ThenominalvoltageforallXNXtransmittersis24Vwiththe
powerrequired dependingonthenumberofpointsusingthe
samepowersupply�
XNX Universal Transmitter Maximum Power Consumption
Conguration
-40°C to +65°C -10°C to +65°C
HART
over
4-20mA
(watts)
HART over 4-20mA
with Relay, Modbus
®
, or
Foundation
TM
Fieldbus
(watts)
HART
over
4-20mA
(watts)
HART over 4-20mA
with Relay, Mod-
bus, or Foundation
Fieldbus
(watts)
XNXwithtoxic
sensors
5.1 6.2 3.4 4.5
XNXwithcatalytic
sensors
5.4 6.5 3.7 4.8
XNXwithinfrared
cartridge
5.4 6.5 3.7 4.8
XNXwithSearchpoint
OptimaPlus
8.6 9.7 6.9 8.0
XNXwith
SearchlineExcel
12.1 13.2 10.4 11.5
Asageneralguideline,thepowersupplyshouldbecapable
ofprovidingmorepowerthanisrequiredbytheinstallation�A
10wattpowersupplyisneforasingleXNXmVwithcatalytic
sensor(6�5wattsrequired,seethefollowingtable)butis
inadequateforasingleXNXIRwithSearchpointOptimaPlus(10
wattsrequired)�
Todeterminethewattagerequired,addthemaximumpower
requirementsofallthepointsthatwillsharethepowersupply�
Forexample,considerasystemwithtwoXNXmVtransmitters
withcatalyticsensors(6�5wattseach)andoneXNXIRwith