Model 5081 Family of Two-wire Transmitters
• CHOICE OF COMMUNICATION PROTOCOL:
HART® or FOUNDATION Fieldbus.
• LARGE, EASY-TO-READ two-line display shows the
process measurement and temperature.
• SIMPLE MENU STRUCTURE.
• ROBUST NEMA 4X and NEMA 7B ENCLOSURE.
• INTRINSICALLY SAFE DESIGN allows the transmitter to
be used in hazardous environments (with appropriate safety
barriers).
• NON-VOLATILE MEMORY retains program settings and

calibration data during power failures.

FEATURES AND APPLICATIONS
The Model 5081 family of transmitters can be used to
measure pH, ORP, conductivity (using either contacting
or toroidal sensors), resistivity, oxygen (ppm and
ppb level), free chlorine, total chlorine, and ozone in a
variety of process liquids. The 5081 is compatible with
most Rosemount Analytical sensors. See the Specification
sections for details.
The transmitter has a rugged, weatherproof, corrosion-
resistant enclosure (NEMA 4X and IP65) of
epoxy-painted aluminum. The enclosure also meets
NEMA 7B explosion-proof standards.
The transmitter has a two-line seven-segment display.
The main measurement appears in 0.8-inch (20 mm)
high numerals. The secondary measurement, temperature
(and pH if free chlorine is being measured),
appears in 0.3-inch (7 mm) high digits.

Two digital communication protocols are available:
HART (model option -HT) and Foundation Fieldbus
(model options -FF or -FI). Digital communications
allows access to AMS (Asset Management Solutions).
Use AMS to set up and configure the transmitter, read
process variables, and troubleshoot problems from a
personal computer or host anywhere in the plant.
A handheld infrared remote controller or the HART and
Foundation Fieldbus Model 375 communicator can
also be used for programming and calibrating the
transmitter. The remote controller works from as far
away as six feet.

Model 5081-P pH/ORP Transmitter
• CHANGING FROM pH TO ORP operation takes only seconds.
• AUTOMATIC TWO-POINT BUFFER CALIBRATION reduces errors.
• SOLUTION TEMPERATURE COMPENSATION converts measured pH
to the pH at 25°C.
• CONTINUOUS DIAGNOSTICS monitor sensor performance and warn
the user of failure (FAULT) or approaching failure (WARNING).

Model 5081-T Toroidal Conductivity Transmitter
• MEASURES CONDUCTIVITY, PERCENT CONCENTRATION, OR
CUSTOM CURVE VARIABLE.
• AUTOMATIC TC RECOGNITION simplifies start up.
• AUTOMATIC/MANUAL TEMPERATURE COMPENSATION ensures
accurate monitoring and control.
• BUILT-IN CONCENTRATION CURVES FOR 0-12% NaOH, 0-15% HCl,
0-25% and 96-99.7% H2SO4.
• PROGRAMMABLE REFERENCE TEMPERATURE enables temperature
compensation to temperatures other than 25 degrees Celsius.
• AUTOMATIC COMPENSATION FOR SENSOR CABLE RESISTANCE
improves accuracy of high conductivity measurements.

Model 5081-C Contacting Conductivity Transmitter
• MEASURES CONDUCTIVITY, RESISTIVITY, OR CUSTOM CURVE
VARIABLE.
• AUTOMATIC TC RECOGNITION simplifies start up.
• AUTOMATIC/MANUAL TEMPERATURE COMPENSATION ensures
accurate monitoring and control.
• AUTOMATIC COMPENSATION FOR SENSOR CABLE RESISTANCE improves accuracy
of high conductivity/ low resistivity measurements.
• BUILT-IN TEMPERATURE COMPENSATION ALGORITHMS include straight slope, ultrapure
water, cation conductivity, and no compensation.

Model 5081-A Amperometric Transmitter
• MEASURES dissolved oxygen (ppm and ppb level), free chlorine,
total chlorine, and ozone.
• SECOND INPUT FOR A pH SENSOR ALLOWS AUTOMATIC pH
CORRECTION for free chlorine measurement. No expensive, messy
reagents needed.
• AUTOMATIC BUFFER RECOGNITON FOR pH CALIBRATION.