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Smart temperature transmitter, single or dual universal input, 4-20 mA and HART or Honeywell DE protocols, or Foundation Fieldbus. 125 mSec update time, digial accuracy to ±0.10° C (Pt100Ω). Replaces the retired Honeywell STT350 temperature transmitter.
Honeywell SmartLine STT850 temperature transmitters deliver high accuracy and stability across a wide ambient temperature range. Built on the SmartLine modular platform, they include polarity insensitive wiring connections and built-in diagnostics for low total cost of ownership and easy maintenance.
- Single or dual universal input for RTDs, thermocouples, mV, and Ohms
- Digital accuracy up to 0.1°C for RTD
- 125 mSec update time for single inputs, 250 mSec update for dual inputs
- Stability up to ±0.01% upper range limit per year for 10 years
- Advanced graphics LCD display: Up to 8 display screens, two line x 16 character, displays up to six data points, and can rotate 0°, 90°, 180°, or 270° position for optimal visibility
- Integral three-button configuration for zero, span, and other options
- For HART configuration, use handheld HART communicator, Field Device Manager (FDM), or Pactware with a HART modem. For DE configuration, use Honeywell SCT3000 software. For Foundation Fieldbus, use FDM
- Dual input for differential, averaging, redundant, or split range measurement
- Built-in galvanic isolation and sensor break protection
- Comprehensive on-board diagnostics for transmitter and sensors
- 4-20 mA DC analog output, HART 7 and digital output, Honeywell DE, and Foundation Fieldbus models
- Alarms for PV high, PV low, critical diagnostics, redundant input, PV rate of change, PV deviation
- Dual compartment housing
- Full compliance to SIL 2/3 requirements
- FM, CSA, ATEX, IECEx approvals


Model Selection Guide
Use this table to find the right model for your application. Don't see the option you need? Call a Lesman sales specialist at 800-953-7626.
Make one selection from each table section below to build your complete model number. Make note of the Availability column to be sure you're building a valid transmitter. A complete STT850 model number looks like this: STT750- _ - _- _ -_ _ _- _ _ _ - _ - _ _ _ _ - _ _ - 0000
| Description | Catalog Number | Availability | |
|---|---|---|---|
| Temperature Transmitter, Universal Input, Factory Standard Configuration | STT850 | ● | |
| Inputs | Single Temperature Input | S- | ● |
| Dual Temperature Inputs | T- | e | |
| Digital Output | No Digital Output | 0- | ● |
| With Digital Output | 1- | a | |
| Approvals | None | 0- | ● |
| FM Approved | A- | e | |
| CSA Approved | B- | ● | |
| ATEX Approved | C- | ● | |
| IECEx Approved | D- | ● | |
| Electronic Housing | Aluminum Housing, 1/2" NPT Connection | A _ _ - | ● |
| Aluminum Housing, 1/2" NPT Connection, Lightning Protection | C _ _- | ● | |
| 316 Stainless Steel Housing, 1/2" NPT Connection | E _ _ - | ● | |
| 316 Stainless Steel Housing, 1/2" NPT Connection, Lightning Protection | G _ _ - | ● | |
| Output | 4-20 mA DC Analog Output, HART Protocol | _ H _ - | ● |
| 4-20 mA DC Analog Output, Honeywell DE Protocol | _ D _ - | ● | |
| Foundation Fieldbus Digital Protocol | _ F _- | ● | |
| Interface | No Indicator, No Configuration Buttons | _ _ 0- | ● |
| No Indicator, Zero/Span Configuration Buttons | _ _ A- | f | |
| Basic Digital Indicator, No Configuration Buttons | _ _B- | ● | |
| Basic Digital Indicator, Configuration Button Interface | _ _ C- | ● | |
| Advanced Digital Indicator, No Configuration Button Interface | _ _ D- | ● | |
| Advanced Digital Indicator, Configuration Button Interface | _ _ E- | ● | |
| Diagnostics | Standard Diagnostics | 1 _ _- | ● |
| Advanced Diagnostics: Rate of Change and Deviation Alarm | 2 _ _- | c | |
| Configuration | No Write Protection, Fail High, Standard High/Low Output Limits | _ 1S- | f |
| No Write Protection, Fail Low, Standard High/Low Output Limits | _ 2S- | f | |
| Write Protection, Fail High, Standard High/Low Output Limits | _ 3S- | f | |
| Write Protection, Fail Low, Standard High/Low Output Limits | _ 4S- | f | |
| Write Protection, Fieldbus High/Low Output Limits | _ 5S- | g | |
| No Write Protection, Fieldbus High/Low Output Limits | _ 6S- | g | |
| Calibration | Factory Standard Single Calibration | A- | ● |
| Custom Single Calibration (Unit Data Required) | B- | ● | |
| Mounting Bracket | None | 0 _ _ _- | ● |
| Carbon Steel Flat Pipe Mounting Bracket | 1 _ _ _- | ● | |
| Carbon Steel Angle Pipe Mounting Bracket | 2 _ _ _- | ● | |
| Carbon Steel Wall Mounting Bracket | 5 _ _ _- | ● | |
| 316 SS Flat Pipe Mounting Bracket | 3 _ _ _- | ● | |
| 316 SS Angle Pipe Mounting Bracket | 4 _ _ _- | ● | |
| 316 SS Wall Mounting Bracket | 6 _ _ _- | ● | |
| Tag | None | _ 0 _ _- | ● |
| Wired Stainless Steel Tag (Up to 4 Lines, 26 Char Ea.) | _ 1 _ _- | ● | |
| Conduit Plugs and Connectors | None | _ _ A0- | ● |
| 1/2" NPTM to 3/4" NPTF 316 SS Certified Conduit Adapter | _ _ A2- | ● | |
| 1/2" NPT 316 SS Certified Conduit Plug | _ _ A6- | ● | |
| 1/2" NPT Minifast® 4-Pin (Not for Explosion-Proof Use) | _ _ A8- | ● | |
| Certifications | None | 00- | ● |
| Calibration Test Report, Certificate of Compliance | F1- | ● | |
| Certificate of Origin | F5- | ● | |
| SIL 2/3 Certification | FE- | j | |
Restrictions
a Available only on single input models.
c Not available with Honeywell DE protocol.
e Not available with digital output.
f Not available with Foundation Fieldbus.
g Available only on Foundation Fieldbus models.
j Available only with HART communications and write protection enabled.
| Is FM | No |
|---|---|
| HART | Yes |
| SIL-Rated | Yes |
To build your complete part number, make a selection from each table section below. Your completed model and its price will appear in the Results section. If you don't see the options you need, call us.
Results
| Please complete your model selections. |



