Transmitter Overview - Emerson Rosemount 644 with HART Protocol Reference Manual

Introduction
July 2018
1.1.1

Transmitter overview

The Rosemount 644 Head Mount and Field Mount Temperature Transmitters support the following
features:
HART configuration with Selectable HART revision capability (Revisions 5 or 7)

Accepts either 1 or 2 inputs from a wide variety of sensor types (2-, 3-, and 4-wire RTD, thermocouple,

mV and Ohm)
A compact transmitter size with electronics completely encapsulated in protective silicone and

enclosed in a plastic housing ensuring long-term transmitter reliability
Optional Safety Certification Option (IEC 61508 SIL 2)

Optional enhanced accuracy and stability performance

Optional LCD display with extended temperature ratings of –40 to 85 °C

Optional advanced LCD display with local operator interface (LOI)

The Rosemount 644 Head Mount Transmitter is available in two housing materials (Aluminum and

SST) and various housing options that allow for mounting flexibility in a variety of environmental
conditions. The Rosemount 644 Field Mount is available in an aluminum housing.
Special dual-sensor features include Hot Backup

average temperature measurements, and four simultaneous measurement variable outputs in
addition to the analog output signal.
Additional advanced features include: Thermocouple degradation diagnostic, which monitors

thermocouple health, and process and transmitter minimum/maximum temperature tracking.
The Rosemount 644 Rail Mount Temperature Transmitter supports the following features:
4–20 mA/HART protocol (Revision 5)

Accepts one sensor input from a wide variety of sensor types (2-, 3-, and 4-wire RTD, Thermocouple,

mV and Ohm)
Completely encapsulated electronics to ensure long term transmitter reliability

Refer to the following literature for a full range of compatible connection heads, sensors, and
thermowells provided by Emerson.
Rosemount Volume 1 Temperature Sensors and Accessories (English)

Rosemount DIN-Style Temperature Sensors and Thermowells (Metric)

2
™
, Sensor Drift Alert, first good, differential and
Product Data Sheet
Product Data Sheet
Reference Manual
00809-0200-4728 Rev SA
Introduction