Honeywell STT850 SMARTLINE User manual

Honeywell Process Solutions
STT850 SMARTLINE
Temperature Transmitter
User’s Manual
34-TT-25-03
Revision 1
March 2014

Page ii STT850 Temperature Transmitter User’s Manual Revision 1
Copyrights, Notices and Trademarks
© Copyright 2014 by Honeywell, Inc.
Revision 1, March 2014
While the information in this document is presented in good faith and believed to be
accurate, Honeywell disclaims any implied warranties of merchantability and fitness for a
particular purpose and makes no express warranties except as may be stated in the written
agreement with and for its customers. In no event is Honeywell liable to anyone for any
indirect, special, or consequential damages. The information and specifications in this
document are subject to change without notice.
Honeywell, TDC 3000, SFC, Smartline, PlantScape, Experion PKS, and TotalPlant are
registered trademarks of Honeywell International Inc. Other brand or product names are
trademarks of their respective owners.
Honeywell Process Solutions
1250 W Sam Houston Pkwy S
Houston, TX 77042

Revision 1 STT850 Temperature Transmitter User’s Manual Page iii
About This Manual
This manual is a detailed how to reference for installing, piping, wiring, configuring, starting up,
operating, maintaining, calibrating, and servicing Honeywell’s family of STT850 Temperature
Transmitters. Users who have a Honeywell STT850 SmartLine Temperature Transmitter
configured for HART protocol or Honeywell’s Digitally Enhanced (DE) are referred to the
STT850 SmartLine Series HART/DE Option User’s Manual, document number 34-TT-25-06.
Users who have a Honeywell STT850 SmartLine Temperature Transmitter configured for
Fieldbus operation are referred to the STT850 SmartLine Series Fieldbus Option User’s Manual,
document number (34-TT-25-07).
The configuration of your Transmitter depends on the mode of operation and the options selected
for it with respect to operating controls, displays and mechanical installation. This manual
provides detailed procedures to assist first-time users, and it further includes keystroke
summaries, where appropriate, as quick reference or refreshers for experienced personnel.
To digitally integrate a Transmitter with one of the following systems:
•For the Experion PKS, you will need to supplement the information in this document with the
data and procedures in the Experion Knowledge Builder.
•For Honeywell’s TotalPlant Solutions (TPS), you will need to supplement the information in this
document with the data in the PM/APM SmartLine Transmitter Integration Manual, which is
supplied with the TDC 3000 book set. (TPS is the evolution of the TDC 3000).
Release Information:
STT850 SmartLine Temperature Transmitter User Manual, Document # 34-TT-25-03,
Rev 1, March 2014 1st Release

Page iv STT850 Temperature Transmitter User’s Manual Revision 1
References
The following list identifies publications that may contain information relevant to the information
in this document.
STT850 SmartLine Temperature Transmitter Quick Start Installation Guide, Document # 34-TT-
25-04
STT850 SmartLine Temperature Transmitter with HART Communications Options Safety
Manual, # 34-TT-25-05
STT850 SmartLine Temperature Transmitter HART/DE Option User’s Manual, Document
# 34-TT-25-06
STT850 FF Transmitter with FOUNDATION Fieldbus Option Installation & Device Reference
Guide, Document # 34-TT-25-07
MC Toolkit User Manual, for 400 or later, Document # 34-ST-25-20
PM/APM SmartLine Transmitter Integration Manual, Document # PM 12-410
STT850 Series Temperature, Transmitter, Agency IS Control Drawing50091227
Smart Field Communicator Model STS 103 Operating Guide, Document # 34-ST-11-14
Patent Notice
The Honeywell STT850 SmartLine Temperature Transmitter family is covered by one or more of the
following U. S. Patents: 5,485,753; 5,811,690; 6,041,659; 6,055,633; 7,786,878; 8,073,098; and other
patents pending.
Support and Contact Information
For Europe, Asia Pacific, North and South America contact details, refer to the back page of this
manual or the appropriate Honeywell Solution Support web site:
Honeywell Corporate www.honeywellprocess.com
Honeywell Process Solutions https://www.honeywellprocess.com/smartline-temperature/
Training Classes http://www.automationccollege.com
Telephone and Email Contacts
Area Organization Phone Number
United States and
Canada
Honeywell Inc.
1-800-343-0228 Customer Service
1-800-423-9883 Global Technical Support
Global Email
Support
Honeywell Process
Solutions
[e-mail]

Revision 1 STT850 Temperature Transmitter User’s Manual Page v
Symbol Descriptions and Definitions
The symbols identified and defined in the following table may appear in this document.
Symbol Definition
ATTENTION: Identifies information that requires special consideration.
TIP: Identifies advice or hints for the user, often in terms of performing a
task.
CAUTION Indicates a situation which, if not avoided, may result in equipment or work
(data) on the system being damaged or lost, or may result in the inability to
properly operate the process.
CAUTION: Indicates a potentially hazardous situation which, if not avoided,
may result in minor or moderate injury. It may also be used to alert against
unsafe practices.
CAUTION symbol on the equipment refers the user to the product manual for
additional information. The symbol appears next to required information in
the manual.
WARNING: Indicates a potentially hazardous situation, which, if not avoided,
could result in serious injury or death.
WARNING symbol on the equipment refers the user to the product manual
for additional information. The symbol appears next to required information
in the manual.
WARNING, Risk of electrical shock: Potential shock hazard where
HAZARDOUS LIVE voltages greater than 30 Vrms, 42.4 Vpeak, or 60 VDC
may be accessible.
ESD HAZARD: Danger of an electro-static discharge to which equipment may
be sensitive. Observe precautions for handling electrostatic sensitive
devices.
Protective Earth (PE) terminal: Provided for connection of the protective
earth (green or green/yellow) supply system conductor.
Functional earth terminal: Used for non-safety purposes such as noise
immunity improvement. NOTE: This connection shall be bonded to
Protective Earth at the source of supply in accordance with national local
electrical code requirements.
Earth Ground: Functional earth connection. NOTE: This connection shall be
bonded to Protective Earth at the source of supply in accordance with
national and local electrical code requirements.
Chassis Ground: Identifies a connection to the chassis or frame of the
equipment shall be bonded to Protective Earth at the source of supply in
accordance with national and local electrical code requirements.
continued

Page vi STT850 Temperature Transmitter User’s Manual Revision 1
Symbol Description
The Factory Mutual®Approval mark means the equipment has been rigorously
tested and certified to be reliable.
The Canadian Standards mark means the equipment has been tested and meets
applicable standards for safety and/or performance.
The Ex mark means the equipment complies with the requirements of the
European standards that are harmonized with the 94/9/EC Directive (ATEX
Directive, named after the French "ATmosphere EXplosible").

Revision 1 STT850 Temperature Transmitter User’s Manual Page vii
Contents
1Introduction....................................................................................................................................1
1.1 Overview ................................................................................................................................1
1.2 Features and Options..............................................................................................................1
1.2.1 Physical Characteristics..................................................................................................1
1.2.2 Functional Characteristics..............................................................................................2
1.3 STT850 SmartLine Transmitter Name Plate..........................................................................3
1.4 Safety Certification Information.............................................................................................3
1.5 Transmitter Adjustments........................................................................................................3
1.6 Display Options......................................................................................................................4
1.7 Optional 3-Button Assembly..................................................................................................4
2Application Design.........................................................................................................................5
2.1 Overview ................................................................................................................................5
2.2 Safety......................................................................................................................................5
2.2.1 Accuracy.........................................................................................................................5
2.2.2 Diagnostic Messages ......................................................................................................5
2.2.3 Safety Integrity Level (SIL) ...........................................................................................6
3Installation and Startup...................................................................................................................7
3.1 Installation Site Evaluation.....................................................................................................7
3.2 Honeywell MC Toolkit...........................................................................................................7
3.3 Display Installation Precautions.............................................................................................7
3.4 Mounting STT850 SmartLine Temperature Transmitters......................................................8
3.4.1 Summary.........................................................................................................................8
3.4.2 Mounting Dimensions....................................................................................................8
3.4.3 Bracket Mounting Procedure..........................................................................................8
3.5 Wiring a Transmitter ..............................................................................................................9
3.5.1 Loop Power Overview....................................................................................................9
3.5.2 Digital System Integration Information........................................................................11
3.5.3 Wiring Variations.........................................................................................................11
3.5.4 Loop Wiring Procedure................................................................................................11
3.5.5 Grounding and Lightning Protection............................................................................12
3.5.6 Supply Voltage Limiting Requirements.......................................................................12
3.5.7 Process Sealing.............................................................................................................12
3.5.8 Explosion-Proof Conduit Seal......................................................................................12
3.5.9 Input Sensor Wiring .....................................................................................................13
3.5.10 Digital Output Wiring...................................................................................................15
3.6 Startup ..................................................................................................................................16
3.6.1 Overview ......................................................................................................................16
3.6.2 Startup Tasks................................................................................................................16
3.6.3 Output Check Procedures.............................................................................................17
3.6.4 Constant Current Source Mode Procedure...................................................................18
4Operation......................................................................................................................................19
4.1 Overview ..............................................................................................................................19
4.2 Three-Button Operation........................................................................................................19
4.2.1 Menu Navigation..........................................................................................................20
4.2.2 Data Entry.....................................................................................................................20
4.2.3 Editing a Numeric Value..............................................................................................21
4.2.4 Selecting a new setting from a list of choices ..............................................................21
4.2.5 The Advanced Display Menus .....................................................................................22

Page viii STT850 Temperature Transmitter User’s Manual Revision 1
4.2.6 The Basic Display Menu.............................................................................................. 34
4.2.7 Selecting a new setting from a list of choices.............................................................. 39
4.3 Three Button Operation with no Display Installed.............................................................. 40
4.3.1 Zero Adjustment .......................................................................................................... 40
4.3.2 Span Adjustment.......................................................................................................... 40
4.4 Changing the Default Failsafe Direction.............................................................................. 41
4.4.1 DE and Analog Differences......................................................................................... 41
4.4.2 Procedure to Establish Failsafe Operation................................................................... 41
4.5 Monitoring the Basic and Advanced Displays..................................................................... 44
4.5.1 Basic Display ............................................................................................................... 44
4.5.2 Advanced Displays ...................................................................................................... 44
4.5.3 Button operation during monitoring............................................................................. 46
5Maintenance................................................................................................................................. 47
5.1 Overview.............................................................................................................................. 47
5.2 Preventive Maintenance Practices and Schedules................................................................ 47
5.3 Replacing the Communication Module ............................................................................... 47
6Calibration.................................................................................................................................... 51
6.1 Recommendations for Transmitter Calibration.................................................................... 51
6.2 Calibration Procedures......................................................................................................... 51
7Troubleshooting........................................................................................................................... 53
7.1 Overview.............................................................................................................................. 53
7.2 Critical Diagnostics Screens ................................................................................................ 53
7.2.1 Fault Conditions and Recommended Corrective Actions............................................ 54
8Parts List ...................................................................................................................................... 55
8.1 Overview.............................................................................................................................. 55
Appendix A. PRODUCT CERTIFICATIONS.................................................................................... 59
Glossary............................................................................................................................................... 71

Revision 1 STT850 Temperature Transmitter User’s Manual Page ix
List of Figures
Figure 1 – STT850 Major Assemblies ...................................................................................................2
Figure 2 – Electronics Housing Components.........................................................................................2
Figure 3 –Typical STT850 Name Plate..................................................................................................3
Figure 4 – Typical Bracket Mounted Installations.................................................................................8
Figure 5 – Pipe Mounting Bracket Secured to a Horizontal or Vertical Pipe........................................9
Figure 6 – HART Transmitter Operating Ranges ..................................................................................9
Figure 7 – Transmitter 9-Screw Terminal Board and Grounding Screw .............................................10
Figure 8 – Thermocouple, mV and Volt Connections..........................................................................13
Figure 9 – RTD and Ohm Connections................................................................................................14
Figure 10– Remote C/J and Mixed Sensors Connections (Not available on DE Models)...................15
Figure 11– Digital Output Connections for mA Load..........................................................................15
Figure 12– Digital Output Connections for PLC Counting Input ........................................................16
Figure 13 – Current Loop Test Connections........................................................................................18
Figure 14 – Three-Button Option.........................................................................................................19
Figure 15 – Locating the Failsafe and Write Protect Jumpers..............................................................42
Figure 16 – Basic Display with Process Variable Format....................................................................44
Figure 17 – Advanced Display Formats with the Process Variable.....................................................45
Figure 18 – PWA Replacement............................................................................................................47
Figure 19 – Local Display Fault Diagnostic Conditions......................................................................53
Figure 20 – Pipe and Wall Bracket Parts..............................................................................................56
Figure 21 – Electronic Housing, Display End......................................................................................57
Figure 22 – Electronic Housing, Terminal Block End.........................................................................58

Page x STT850 Temperature Transmitter User’s Manual Revision 1
List of Tables
Table 1 – Features and Options.............................................................................................................. 1
Table 2 – Available Display Characteristics.......................................................................................... 4
Table 3 – STT850 Standard Diagnostics Messages............................................................................... 5
Table 4 – Three-Button Option Functions........................................................................................... 20
Table 5 – Three-Button Data Entry...................................................................................................... 21
Table 6 – Advanced Display Main Menu Structure............................................................................. 22
Table 7 –Diagnostics Menu................................................................................................................. 23
Table 8 –Display Setup Menus............................................................................................................ 25
Table 9 –Calibration Menus................................................................................................................. 27
Table 10 –Transmitter Setup Menus.................................................................................................... 29
Table 11 –Information Menus ............................................................................................................. 33
Table 12 – The Basic Display Menus.................................................................................................. 34
Table 13 – Hart and DE Failsafe and Write Protect Jumpers.............................................................. 42
Table 14 – Fieldbus Simulation and Write Protect Jumpers................................................................ 43
Table 15 – Advanced Displays with PV Format Display Indications.................................................. 45
Table 16 – Fault Conditions and Recommended Corrective Actions.................................................. 54
Table 17 – Summary List of Recommended Spare Parts .................................................................... 55
Table 18 – Pipe and Wall Bracket Parts .............................................................................................. 56
Table 19 – Transmitter Major Assemblies........................................................................................... 57

Revision 1 STT850 Temperature Transmitter User’s Manual Page 1
1 Introduction
1.1 Overview
This section is an introduction to the physical and functional characteristics Honeywell’s family of
STT850 SmartLine Temperature Transmitters.
1.2 Features and Options
The STT850 SmartLine Temperature Transmitter is available in a variety of models for measuring
Thermocouples, RTD, Millivolts, and Volt or ohm sensor types. Table 1lists the protocols, human
interface (HMI), materials, approvals, and mounting bracket options for the STT850.
Table 1 – Features and Options
Feature/Option Standard/Available Options
Communication Protocols
HART version 7, Digitally Enhanced (DE), Fieldbus
Human-Machine Interface (HMI)
Options (Basic and Advanced Display)
Basic and Advanced Digital Display
Three-button programming (optional)
Basic display language: English only
Advanced display languages: English, German, French,
Spanish, Turkish, Italian, Chinese, Japanese and Russian
Calibration
Single
Approvals (See Appendix C for details.)
ATEX, CSA, FM, IECx, NEPSI
Mounting Brackets
Pipe mounting and wall mounting brackets in carbon steel
and 316 stainless steel.
Integration Tools
Experion
1.2.1 Physical Characteristics
As shown in Figure 1, the STT850 is packaged in one major assembly: the Electronics Housing. The
elements in the Electronic Housing are connected to the process sensors, measure the process
variables, respond to setup commands and execute the software and protocol for the different
temperature measurement types. Figure 2 shows the assemblies in the Electronics Housing with
available options.

Page 2 STT850 Temperature Transmitter User’s Manual Revision 1
Figure 1 – STT850 Major Assemblies
Figure 2 – Electronics Housing Components
1.2.2 Functional Characteristics
Functionally, the Transmitter can measure process sensors and provides a proportional analog 4 to
20 mA output to the measured process variable (PV). Available output communication protocols
include Honeywell Digitally Enhanced (DE), HART, and FOUNDATION Fieldbus.
An optional 3-button assembly is available to set up and make adjustments to the Transmitter. In
addition, a Honeywell Multi-Communication (MC) Toolkit (not supplied with the Transmitter) can
facilitate setup and adjustment procedures. Certain adjustments can be made through an Experion
Station or a Universal Station if the Transmitter is digitally integrated with Honeywell’s Experion or
TPS/TDC 3000 control system.

Revision 1 STT850 Temperature Transmitter User’s Manual Page 3
1.3 STT850 SmartLine Transmitter Name Plate
The Transmitter nameplate mounted on the bottom of the electronics housing (see Figure 1) lists its
model number, physical configuration, electronics options, accessories, certifications, and
manufacturing specialties. Figure 3is an example of a typical Temperature Transmitter name plate.
The model number format consists of a Key Number with several table selections.
Figure 3 –Typical STT850 Name Plate
You can readily identify the series and basic Transmitter type from the key number. The letter in the
third digit represents one of these basic transmitter types:
•T = Temperature
For a complete selection breakdown, refer to the appropriate Specification and Model Selection
Guide provided as a separate document.
1.4 Safety Certification Information
An “approvals” name plate is located on the bottom of the Electronics Assembly; see Figure 1for
exact location. The approvals name plate contains information and service marks that disclose the
Transmitter compliance information. Refer to Appendix C of this document for safety certification
requirements and details.
1.5 Transmitter Adjustments
Zero and Span adjustments are possible in STT850 SmartLine Temperature Transmitters with the
optional three-button assembly located at the top of the Electronic Housing (see Figure 2).
You can also use the Honeywell MC Toolkit or other third-party hand-held zero to make any
adjustments to an STT850 SmartLine Temperature Transmitter. Alternately, certain adjustments can
be made through the Experion or Universal Station, if the Transmitter is digitally integrated with a
Honeywell Experion or TPS system.
Key III III IV VVI VII VIII IX
STT850 -_ - _ - _ - _ _ _ -_ _ _ - _ - _ _ _ _ -_ _, _ _, _ _ -X X X X

Page 4 STT850 Temperature Transmitter User’s Manual Revision 1
1.6 Display Options
The STT850 SmartLine Temperature Transmitter has two display options: Basic and Advanced; see Table 2.
Table 2 – Available Display Characteristics
Basic Display
•Suitable for basic process needs
•360orotation in 90oincrements
•2 lines,16 characters
•Standard units of measurement: °F, °C, °R, °K, Ω, mV & %
•Diagnostic messaging
Advanced Display
•Suitable for custom and complex process needs
•360° rotation in 90° increments
•Three (3) configurable screen formats with configurable rotation timing
oLarge process variable (PV)
oPV with bar graph
oPV with trend (1-960 hours (allows 30 days), configurable)
•Eight (8) screens with 3-30 seconds rotation timing
•Standard engineering units
•Diagnostic alerts and diagnostic messaging
•Multiple language support:
oEN, FR, GE, SP, RU, IT, TK
oEN, CH (Kanji), JP
•Supports 3-button configuration and calibration
•Supports transmitter messaging, and maintenance mode indications
1.7 Optional 3-Button Assembly
The optional 3-Button Assembly provides the following features and capabilities:
•Increment, decrement, and enter key functions.
•With the menu-driven display:
oComprehensive on-screen menu for navigation.
oTransmitter configuration.
oTransmitter calibration
oDisplay configuration.
oSet zero and span parameters.

Revision 1 STT850 Temperature Transmitter User’s Manual Page 5
2 Application Design
2.1 Overview
This section discusses the considerations involved with deploying a Honeywell STT850 SmartLine
Temperature Transmitter in a process system. The following areas are covered:
•Safety
•Input and output data
•Reliability
•Environmental limits
•Installation considerations
•Operation and maintenance\
•Repair and replacement
2.2 Safety
2.2.1 Accuracy
The STT850 SmartLine Temperature Transmitter (Transmitter) measures the temperature of a process
and reports the measurement to a receiving device.
2.2.2 Diagnostic Messages
Transmitter standard diagnostics are reported in the two basic categories listed in Table 3. Problems
detected as critical diagnostics drive the analog output to the programmed burnout level. Problems
detected as non-critical diagnostics may affect performance without driving the analog output to the
programmed burnout level. Informational messages (not listed in Table 3) report various Transmitter
status or setting conditions. The messages listed in Table 3are specific to the Transmitter, exclusive
of those associated with HART and DE protocols. HART and DE diagnostic messages are listed and
described in the STT850 SmartLine Temperature Transmitter HART/DE Option User Manual,
document number 34-TT-25-06.
Table 3 – STT850 Standard Diagnostics Messages
Critical Diagnostics
(Failure Conditions)
Non-Critical Diagnostics (Warning Conditions)
Sensor Comm Timeout
Temperature Sensor Critical
Failure
Sensor Burnout Detection
Comm Module Diag Failure
Config Data Corrupt
Temperature Sensor NVM
Corrupt
Comm Module DAC Failure
Sensor open/short
No DAC Compensation
No Factory Calibration
PV Out of Range
Fixed Current Mode
Ambient temperature out of
range
Sensor resistance high
No DAC Compensation
No Factory Calibration
Local Display
Low Supply Voltage
No DAC Calibration
Tamper Alarm
Loop Current Noise
AO Out of Range
URV Set Error – Span Config
Button
LRV Set Error – Span Config
Button

Page 6 STT850 Temperature Transmitter User’s Manual Revision 1
2.2.3 Safety Integrity Level (SIL)
The STT850 is intended to achieve sufficient integrity against systematic errors by the manufacturer’s
design. A Safety Instrumented Function (SIF) designed with this product must not be used at a SIL
level higher than the statement, without “prior use” justification by the end user or diverse technology
redundancy in the design. Refer to the STT850 Safety Manual, 34-TT-25-05, for additional
information.

Revision 1 STT850 Temperature Transmitter User’s Manual Page 7
3 Installation and Startup
3.1 Installation Site Evaluation
Evaluate the site selected for the STT850 SmartLine Transmitter installation with respect to the
process system design specifications and Honeywell’s published performance characteristics for your
particular model. Some parameters that you may want to include in your site evaluation are:
•Environmental Conditions:
oAmbient Temperature
oRelative Humidity
•Potential Noise Sources:
oRadio Frequency Interference (RFI)
oElectromagnetic Interference (EMI)
•Vibration Sources
oPumps
oMotorized System Devices (e.g., pumps)
oValve Cavitation
•Process Parameters
oTemperature
oMaximum Sensor Input Ratings
3.2 Honeywell MC Toolkit
In preparation for post-installation processes, refer to the MC Toolkit User Manual, Document # 34-
ST-25-20, for battery conditioning and device operation and maintenance information.
3.3 Display Installation Precautions
Temperature extremes can affect display quality. The display can become unreadable at temperature
extremes; however, this is only a temporary condition. The display will again be readable when
temperatures return to within operable limits.
The display update rate may increase at cold temperature extremes, but as with readability, normal
updating resumes when temperatures are within limits for full operability.

Page 8 STT850 Temperature Transmitter User’s Manual Revision 1
3.4 Mounting STT850 SmartLine Temperature Transmitters
3.4.1 Summary
Transmitter models can be attached to a two-inch (50 millimeter) vertical or horizontal pipe using
Honeywell’s optional angle.
Honeywell’s optional wall mounting bracket is also shown below:
Figure 4shows typical bracket-mounted installations.
Figure 4 – Typical Bracket Mounted Installations
3.4.2 Mounting Dimensions
Refer to Honeywell drawing number 50094836 for detailed dimensions of the transmitter assembly.
Abbreviated overall dimensions are also shown on the Specification Sheets for the transmitter
models. This section assumes that the mounting dimensions have already been taken into account and
the mounting area can accommodate the Transmitter.
Refer to Honeywell drawing numbers 50095917 (Pipe Mount) and 50095918 (Wall Mount) for
detailed mounting specifications.
3.4.3 Bracket Mounting Procedure
1. Align the two mounting holes in the transmitter with the two slots in the mounting bracket
and assemble the (2) M8 hex cap screws, (2) lockwashers and (2) flat washers provided.
Rotate transmitter assembly to the desired position and torque the M8 hex cap screws to 27,0
Nm/20,0 Lb-ft maximum.
2. Pipe Mount Option: Refer to Figure 5. Position the bracket on a 2-inch (50.8 mm) horizontal
or vertical pipe, and install a “U” bolt around the pipe and through the holes in the bracket.
Secure the bracket with the nuts, flat washers and lock washers provided.
3. Wall Mount Option: Position the bracket on the mounting surface at the desired location and
secure the bracket to the mounting surface using the appropriate hardware (Wall mounting
hardware requirements to be determined and supplied by the end user).

Revision 1 STT850 Temperature Transmitter User’s Manual Page 9
Figure 5 – Pipe Mounting Bracket Secured to a Horizontal or Vertical Pipe
3.5 Wiring a Transmitter
3.5.1 Loop Power Overview
The transmitter is designed to operate in a two-wire power/current loop with loop resistance and
power supply voltage within the HART operating range shown in Figure 6.
Figure 6 – HART Transmitter Operating Ranges
For DE operation, add 3.0V to these values.

Page 10 STT850 Temperature Transmitter User’s Manual Revision 1
Loop wiring is connected to the Transmitter by simply attaching the positive (+) and negative (–) loop
wires to the positive (+) and negative (–) terminals on the Transmitter terminal block in the
Electronics Housing shown in Figure 7. Connect the Loop Power wiring shield to earth ground only
at the power supply end.
Figure 7 – Transmitter 9-Screw Terminal Board and Grounding Screw
As shown in Figure 7, each Transmitter has an internal terminal to connect it to earth ground.
Optionally, a ground terminal can be added to the outside of the Electronics Housing. Grounding the
Transmitter for proper operation is required, as doing so tends to minimize the possible effects of
noise on the output signal and affords protection against lightning and static discharge. An optional
lightning terminal block can be installed in place of the non-lightning terminal block for Transmitters
that will be installed in areas that are highly susceptible to lightning strikes. As noted above, the Loop
Power wiring shield should only be connected to earth ground at the power supply end.
Wiring must comply with local codes, regulations and ordinances. Grounding may be
required to meet various approval body certification, for example CE conformity. Refer to
Appendix A of this document for details.
Note: Terminal #3 is for loop test and is not applicable for Fieldbus option.
The Transmitter is designed to operate in a two-wire power/current loop with loop resistance and
power supply voltage within the operating range; see Figure 6. With an optional remote meter, the
voltage drop for this must be added to the basic power supply voltage requirements to determine the
required Transmitter voltage (VXMTR) and maximum loop resistance (RLOOP MAX). Additional
consideration is required when selecting intrinsic safety barriers to ensure that they will supply at
least minimum Transmitter voltage (VXMTR MIN), including the required 250 ohms of resistance
(typically within the barriers) needed for digital communications.