Technical Manual

XNX Universal Transmitter
Section 1 - Introduction 11
1.1.2 20 mA/HART
®
Output
All XNX Transmitters provide a 20mA Current Loop with HART
Source (3-Wire) or Isolated (4-Wire) electrical interface based on
installation requirements.
The 20mA current loop output provides an analog indication
of special states, a proportional output to gas concentration
and over range indication per the table below. In the event of
a simultaneous alarm and fault, an alarm condition will always
override a warning state.
Output Description* Notes
1.0 mA Fault
Special
State
Indication
2.0 mA
Warm-up
Inhibit
Bump Test
Calibration
3.0 mA Warning
4-20 mA Gas Concentration
21 mA Over Range
*Alarm conditions always take priority over faults and warnings.
HART Protocol provides digital communications with the XNX
Diagnostics. (See Appendix A HART Protocol for additional
information)
1.1.3 Communications
The XNX Universal Transmitter is registered
with the HART Communication Foundation.
The transmitter uses HART over 4-20mA as the standard
communications protocol. Additional optional communication
interfaces are available: relay communication, Modbus, or
Foundation Fieldbus. Each communication option has a
dedicated option board. For additional information, refer to
Section 1.3 Options.
1.1.4
installation in Class I, Division 1, Groups A, B, C and D Hazardous
Locations. FM Approvals evaluation includes Class I, Zone
not cover daisy-chained XNX combustible gas transmitters, the
use of HART, Modbus, or Foundation Fieldbus protocols for
combustible gas performance. HART, Modbus, or Foundation
Fieldbus protocols can be used only for data collection or record
keeping with regards to combustible gas. The EC cartridge
2
and
standards.
European Community ATEX Directive and the prescribed
protection methods for installation in Potentially Explosive
Atmospheres.
and INMETRO approved (TÜV Rhineland) for compliance with
both U.S. and Brazilian standards.
See Section 6.2 for additional information on applicable
approvals by part number and Section 6.2.1 for marking.
2
“Cartridge” and “sensor” are used interchangeably in this document.
XNX-BT**.***** and XNX-UT**.***** versions are UL classified