SITRANS TH320/TH420

SITRANS TH320/TH420 head-mount temperature transmitters support RTDs and thermocouples for accurate conversion, flexible configuration and reliable monitoring.

Rugged field-mounted temperature transmitters for reliable, accurate measurement, high availability, and plant safety, helping to prevent downtime in SIL 2/3 applications.

The SITRANS TS500’s modular design makes it exceptionally versatile, delivering precise temperature measurements even in harsh industrial environments.

Rail-mounted temperature transmitters for accurate measurement, easy panel integration, and smart diagnostics—from standard loops to high-availability applications.

Designed for head-mount installation, SITRANS TH320 and TH420 combine universal sensor input, easy commissioning and seamless connectivity. TH320 efficiently covers core HART applications, while TH420 adds dual-input operation, drift detection and HART or PROFIBUS PA communication for higher availability. Versions for hazardous areas and safety-related applications support use in demanding plants.

For high-availability applications, SITRANS TH420 keeps measurement running even if one sensor fails. Its dual-input design with hot backup switches automatically to the second sensor, maintaining continuous process visibility.

Configuration via HART or PROFIBUS PA, stored parameter data and practical service functions reduce setup time and simplify replacement. This cuts commissioning effort and brings measuring points back into operation faster.

Advanced diagnostics and, on SITRANS TH420, sensor drift detection help identify sensor issues early. Combined with sensor trim for precise matching, this supports faster calibration and more targeted maintenance.

Resistance thermometers, thermocouples, resistance-type sensors, DC voltage sources

4 … 20mA (SITRANS TH320), HART (SITRANS TH320/420), Profibus PA (SITRANS TH420)

Standard: -50 … +85 °C (-58 … +185 °F); SIL: -40 … +80 °C (-40 … +176 °F)

ATEX, IECEx, FM, CSA; EACEx, NEPSI, Inmetro; SIL 2/3 certification (HART only)

Hardware and software write protection; uninterruptible loop current measurement for tests; alarm backup via 21mA error current

Top input accuracy for Pt100 (IEC60751) +/- 0.04 °C; Stability: +/-0.05 °C (1year) or +/-0.18 °C (5 years); 2x 4-wire RTD connection (TH420)

A bi-color LED shows local status. Input monitoring detects wire breaks and short circuits. SITRANS TH420 adds sensor drift detection. Self-monitoring and lifecycle diagnostics help localize faults and plan maintenance early.

Test terminals let you connect an ammeter anytime for monitoring and plausibility checks without opening the current loop, speeding up commissioning and service. Galvanic isolation ensures stable signals in demanding environments.

SITRANS TH420 supports dual 4-wire inputs with hot backup, switching automatically if a sensor fails. Callendar-van-Dusen sensor trim boosts accuracy. Rated to –40 °C with SIL 2/3 for HART, it suits harsh, safety-critical use.

Siemens products and services have created substantial reductions in greenhouse gas emissions for the company’s customers. In 2011, Siemens helped its customers reduce annual CO2 emissions by about 320 million tons.

Chemical recycling tackles the scrap plastic challenges. Engineers from Eurex Oil and Chemosvit Strojchem in Slovakia teamed with Siemens to develop a best-in-class recycling process for environmental friendliness and efficiency.

SITRANS TH320 and TH420 are compact head-mounted transmitters designed for installation in connection heads of type B (DIN 43729) or larger. The operating instructions also describe mounting on DIN rail and G rail.

SITRANS TH320 supports resistance thermometers (2-, 3-, 4-wire), thermocouples, linear resistance, potentiometers and DC voltage sources. SITRANS TH420 supports these signal types as well and, in redundant operation, can connect two resistance thermometers, two thermocouples, or one thermocouple and one resistance thermometer.

SITRANS TH320 can be configured via PC, HART 7 or optional local operation. SITRANS TH420 is configurable via HART or PROFIBUS PA. For the HART variant, configuration can be carried out using a handheld communicator or a HART modem with EDD or DTM in asset management tools such as SIMATIC PDM.

There are several benefits, like up to 32 devices on one PROFIBUS PA segment, backward compatibility with PROFIBUS PA profile 3.x, and no GSD file update required when replacing the previous SITRANS TH400PA. Recording of supply voltage on the PA variant and diagnostic messages improve lifecycle transparency.

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