Honeywell XNX, Technical Manual

Page: 34 / 200

XNX Universal Transmitter
Section 2 - Installation and Operation 32
• Fewer power sources�
Disadvantages:
• Larger power source will be needed
• If a power source fails, several monitoring points fail�
Multiple Transmitters Connected in a “Daisy-Chain”
Configuration
This configuration consists of two or more transmitters installed
in a line� The power connections are installed as an extension of
the previous transmitter, with the first transmitter being the only
one actually wired to the power source�
Class 2
Power Supply
Figure 31. Daisy-chained transmitters from one power supply
Advantages:
• Less wire needed for installation
• Fewer power sources�
Disadvantages:
• Requires a larger power source
• Shorter distance between power source and transmitters�
• If a power source fails, several monitoring points fail�
Note: CSA/FM certification does not cover daisy-chained XNX combus-
tible gas transmitters.
Power Source Selection
For each type of installation, selection of power supply is
important� Power supplies are rated by voltage and power�
The nominal voltage for all XNX transmitters is 24V with the
power required depending on the number of points using the
same power supply�
XNX Universal Transmitter Maximum Power Consumption
Configuration
-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)
XNX with toxic
sensors
5.1 6.2 3.4 4.5
XNX with catalytic
sensors
5.4 6.5 3.7 4.8
XNX with infrared
cartridge
5.4 6.5 3.7 4.8
XNX with Searchpoint
Optima Plus
8.6 9.7 6.9 8.0
XNX with
Searchline Excel
12.1 13.2 10.4 11.5
As a general guideline, the power supply should be capable
of providing more power than is required by the installation� A
10 watt power supply is fine for a single XNX mV with catalytic
sensor (6�5 watts required, see the following table) but is
inadequate for a single XNX IR with Searchpoint Optima Plus (10
watts required)�
To determine the wattage required, add the maximum power
requirements of all the points that will share the power supply�
For example, consider a system with two XNX mV transmitters
with catalytic sensors (6�5 watts each) and one XNX IR with