STT850 Smart Temperature Transmitter

STT850 temperature transmitter is designed to deliver very high performance across varying ambient temperatures. The total installed accuracy level of the transmitter, allows the STT850 to replace virtually any transmitter.

Ideal for high-precision temperature measurement in critical industrial processes (e.g., refining, chemical plants) due to high accuracy + stability. Useful where functional safety is required (SIL 2/3). Good for systems needing redundant or differential sensors (dual input). Suitable for environments with electrical noise, thanks to galvanic isolation. Easy maintenance / integration in plants already using SmartLine pressure transmitters (modular design).

Accuracy & Stability

Digital accuracy up to ± 0.10 °C for RTD inputs.

Very good long-term stability: ± 0.01% of URL (upper range limit) per year, for up to 10 years.

Response / Update Time

~130 ms update time for single-input models.

~250 ms for dual-input models.

Universal & Flexible Input Options

Supports a wide range of sensor types: RTD, thermocouples, mV, ohm (universal input) according to different variants.

Option for dual sensors: allows for differential, averaging, redundant, or split-range measurements.

Built-in Isolation

Galvanic (electrical) isolation is built in, helping reduce interference.

According to Ksource, up to 2000 VDC isolation between input, output, and ground.

Modular & Robust Design

Dual compartment housing: separates electronics / display from terminal wiring, improving safety and maintainability.

Modular construction: display modules and configuration modules are interchangeable (even with SmartLine pressure transmitters).

Polarity-insensitive loop wiring — works even if loop wires are reversed.

Diagnostics & Sensor Health

On-board comprehensive diagnostics (sensor break detection, drift, etc.).

“Sensor matching” capability to improve reading accuracy by matching transmitter to the specific sensor.

Trend display / health trend via advanced LCD (if display module selected).

Communication / Output Protocols

4–20 mA analog output.

Digital output options: HART (v7), Honeywell Digitally Enhanced (DE), FOUNDATION™ Fieldbus (ITK 6.1.2).

Supports NAMUR diagnostics: e.g., Namur 107 (extended diagnostics), Namur 89 (wire break).

Safety & Reliability

SIL 2 / SIL 3 capable (i.e., functional safety compliance).

Lifetime / long warranty: up to 15-year warranty (according to Honeywell).

Display / Interface

Very flexible display options: basic alphanumeric LCD or advanced graphical LCD can be field-installed.

Display orientation adjustable (0°, 90°, 180°, 270°).

Can display multiple data points: e.g., process value (PV), sensor 1, sensor 2, delta, etc.

Screen rotation timing configurable.

Calibration & Sensor Support

Supports direct entry of Callendar–Van Dusen coefficients (R0, α, δ, β) for calibrated RTD sensors (not on all protocol variants).

External zero, span, and configuration can be done via external buttons.

Certifications and Hazardous Area Ratings

Available in versions for hazardous areas: multiple markings (e.g., Ex d, Ex ia, Ex n) according to certain variants.

Housing materials: versions with 316 stainless steel, or aluminum, depending on part number.

Features

  • Digital accuracy up to 0.1°C for RTD
  • Stability up to 0.01% of URL per year for ten years
  • 130 ms update time
  • Sensor matching facility for higher accuracy
  • Built-in digital output option
  • Sensor health trend through advanced display
  • Full compliance with SIL 2/3 requirements
  • Lifetime 15-year warranty.​