OMEGA PRTXD Manual

PRTXD Series
Loop Powered RTD Temperature
Transmitters

M-445 5/0818

PRTXD Series RTD Transmitters

MODEL

PRTXD-4 4” Fixed

PRTXD-4-SL 4” Spring-Loaded

PRTXD-12 12” Fixed

PRTXD-12-SL 12” Spring-Loaded

*

Thermowell required for spring-loaded versions

PROBE

LENGTH

Remote Device

(+)

(–)

PROBE

TYPE

3.5”

*

*

Loop Power

Supply

24 VDC typical

(–)

3.0”

(+)

2.0

(+)RED

(–)BLACK

”

3 ft long,
2-conductor
22 AWG
cable

User’s Guide

Shop online at

omega.com

.75”

1.37”

Probe Length

A

NOTE:

Spring-loaded RTD probes MUST be used with a thermowell. Probe length is measured from
top of full threads to tip of probe. Length = thermowell “A” or “element length” dimension. See
the Omega thermowell specifications. Probe length is NOT the same as thermowell insertion
depth.

0.75”

Continuous

weld on fixed

probe models

0.25” dia.

1.25”

Hex nipple

1/2” NPT x 1/2”

NPT

316 stainless

Spring-Loaded

Models

Approx. 0.25”

longer to compress

element in

thermowell.

0.50” max.

compression

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For latest product manuals:

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TM

WARNING: This product can expose you to chemicals including
lead, nickel and chromium, which are known to the State of
California to cause cancer or birth defects or other reproductive
harm. For more information go to www.P65Warnings.ca.gov

2

PRTXD Series RTD Temperature Transmitters

PRTXD Series RTD Transmitters

MODEL

PROBE

LENGTH

PRTXD-4 4” Fixed

PRTXD-4-SL 4” Spring-Loaded

PRTXD-12 12” Fixed

PRTXD-12-SL 12” Spring-Loaded

*

Thermowell required for spring-loaded versions

Range and Resolution

User selectable °F, °C or K
–58.0°F to 392.0°F
–50.0°C to 200.0°C

220.0K to 475.0K

0.1 degree resolution

Typical Accuracy

Includes linearity error and ±1 LSD
11-point linearization
±0.7°C at –50°C
±0.4°C at 0°C
±0.9°C at 100°C
±1.4°C at 200°C

Sensor

IEC-751 Class B 100 Ω Platinum RTD, 0.00385 alpha curve

1

/2” NPT male, 316L stainless steel

All wetted parts are 316L stainless steel

Thermowell required for spring-loaded versions
Spring-loaded probe fits standard thermowells

Fixed probe pressure rating: 5000 psi max.
Fixed probes are welded to hex fitting

Display

4 readings per second nominal display update rate
4-1/2 digit LCD, 1/2” digit height, alphanumeric lower display
for units

Out of Range Indication

ALARM1 on display above 392°F or 200°C
ALARM2 on display below –58°F or –50°C
Below approx. –103°F (–75°C) or above approx. 482°F
(250°C), the display will indicate 1.-.-.-. and the loop current
will go downscale or upscale depending on programmed
burnout configuration.

Controls & Functions

TEST When held sets loop current and display to test level,
independent of temperature input, to allow testing of
system operation

s Up: increase output or calibration values during setup

t Down: decrease output or calibration values during setup

Loop Supply Voltage

Any DC supply/loop resistance that maintains 8 VDC to 32 VDC
at gauge terminals. Erratic operation may occur if loop voltage
falls below specifications.

Indication on display for low loop power

Reverse polarity protected

Loop Output Characteristics

4-20 mA output configurable to span any part of temperature
range

0.0013 mA loop current resolution for spans greater than 164°F
(90°C)
Output resolution is reduced for spans less than 164°F (90°C)

Updated approximately 4 times per second

Configurable for upscale or downscale burnout

Calibration

User settable passcode to enter calibration mode
Zero and span temperature calibration

Weight

Transmitter: Approx. 12 ounces
Shipping weight: Approx. 1 pound

Material and Color

NEMA 4X ABS/polycarbonate housing, light gray
Gasketed rear cover

Connection and Probe Material

1/2” NPT male hex nipple, 316 stainless steel
316 stainless steel probe sheath

PROBE

TYPE

*

*

Environmental

Storage: –40 to 203°F (–40 to 95°C) at housing
Operating: –4 to 185°F (–20 to 85°C) at housing

Description

The PRTXD series is microprocessor controlled industrial
temperature indicator with a digital temperature display and
4-20 mA retransmission in a rugged NEMA 4X housing. The
PRTXD has a 2-wire connection and all operating power is
supplied by the 4-20 mA current loop.

The RTD temperature reading is linearized for both the digital
display and the 4-20 mA output. The temperature display may
be set up to read °F or °C and the 4-20 mA output may be set
to correspond to a desired temperature range.

Installation and Precautions

A thermowell is required with flowing material, pressurized
applications, and all applications using spring-loaded versions
of the PRTXD.

Install or remove using wrench on probe hex fitting only. Do
not attempt to tighten by turning housing or any other part of
the transmitter. Due to the hardness of 316 stainless steel, it
is recommended that a thread sealant be used to ensure leak­free operation.

Electrical Connections

The 2-wire connection allows the PRTXD to be used as a
temperature display powered by a low-voltage DC source, or
as a loop-powered 4-20 mA transmitter. Connect the loop (+)
supply to the RED lead and the loop (–) supply to the BLACK
lead. Reversing the connections will not harm the transmitter
but it will not operate with incorrect polarity.

Select a loop power supply voltage and total loop resistance so
that when the loop current is 20 mA, the transmitter will have
at least 8 VDC at its terminals. For correct operation and to
avoid erratic or erroneous readings, the terminal voltage must
not fall below 8 VDC. Too large a loop resistance will cause
the output to “limit” or saturate before reaching its full 20 mA
output.

The minimum loop supply voltage may be calculated from the
formula:

Vmin = 8V + (20mA x Total loop resistance)

If the terminal voltage falls below about 7.8 VDC erratic
operation may occur. This is an indication that the loop supply/
resistance may not allow adequate power for reliable operation.
This should never occur in normal use. If it does, examine the
loop supply and resistance.

Operation

The PRTXD is designed for continuous operation. Warm-up
time is negligible. When power is first applied, the PRTXD
will set the loop current to maximum and check the voltage
available. If there is sufficient voltage available to power the
unit, all active segments will be displayed briefly. Then the
display and the loop current will correspond to the temperature
of the RTD probe.

At power-up, if the voltage available is not sufficient, only the
low power segment will be displayed. This is an indication
that the loop impedance is too high or the loop power supply
voltage is too low. After successful power-up, if the loop
voltage falls below the minimum required for reliable operation,
the PRTXD will continue to indicate the temperature of the RTD
with the low power segment blinking at a slow rate.

If the RTD temperature goes above 392°F or 200°C, ALARM1
will be displayed. If the RTD temperature goes below –58°F or
–50°C, ALARM2 will be displayed.

If the RTD temperature continues beyond these limits, the
display will eventually indicate 1.-.-.-. and the loop current will
be minimum if downscale burnout is configured or maximum if
upscale burnout is configured.

Functional Characteristics

The display and the 4-20 mA output are updated
approximately 4 times per second. The RTD probe has a time
constant of approximately 10 seconds, which is typical of an
RTD probe in a stainless sheath.

Time constant is characterized as the RTD changing to 63.2%
of its new temperature span in one time constant, and 95% of
its new temperature span in three time constants.

The RTD resistance measurement is read by an A/D (analog
to digital) converter, linearized by the microprocessor and
displayed on the LCD.

The digitized and linearized RTD signal is also converted to an
analog signal to produce the 4-20 mA output. The 4-20 mA
output can be set to any range within the linearized range of
the PRTXD. The 4-20 mA D/A (digital to analog) conversion will
produce a loop current resolution of approximately 0.0013 mA
for spans as small as 164 F° or 90 C°.

For smaller spans, the A/D resolution is smaller than the D/A
resolution and loop current resolution will decrease. As the
output span setting is further reduced, uneven “stair stepping”
may become noticeable in the output signal. For this reason
extremely small 4-20 mA span settings may be undesirable
and should be avoided.

Passcode Entry

The PRTXD has a user configurable passcode (factory default

3510) that must be entered to access the configuration and
calibration modes.

See the appropriate sections for details on accessing and using
these modes.

Configuration: Hold s and press TEST to CFG

Calibration: Hold t and press TEST to CAL

When the buttons are released, the the upper display will
indicate _ _ _ _ with the left-most position blinking, and the
lower display will indicate PASS.

Pressing and releasing TEST exits passcode entry if no entry
has been made.

Enter the user modifiable passcode.

Use the s up and t down buttons to set the left-most digit to 3.

Press and release the TEST pushbutton to move to the next
position. The 3 will remain, and the second position will be
blinking.

Use the s up and t down buttons to select 5.

Press and release the TEST button to move to the next position.
3 5 will remain, and the third position will be blinking.

Use the s up and t down buttons to select 1.

Press and release the TEST button to move to the next position.
3 5 1 will remain, and the fourth position will be blinking.

Use the s up and t down buttons to select 0.

Press and release the TEST button to continue with calibration
procedures.

Note: If an incorrect passcode was entered, the gauge will exit
to the normal operating mode.

Changing the User Passcode

The passcode can be changed only after entering the factory
passcode as indicated below.

While pressing and holding the s up button, press the TEST
button to enter the configuration mode. The upper section of
the display will indicate CFG.

When all buttons are released, the upper section of the display
will indicate _ _ _ _ with the left-most position blinking, and
the lower section will indicate PASS.

To exit and return to the normal operating mode, press and
release the TEST button.

Enter factory passcode 1220 as follows.

Use the s up and t down buttons to set the left-most digit to 1.

Press and release the TEST button to index to the next position.
The 1 will remain, and the second position will be blinking.

Use the s up and t down buttons to select 2.

Press and release the TEST button to index to the next position.
1 2 will remain, and the third position will be blinking.

Use the s up and t down buttons to select 2.

PRTXD Series RTD Temperature Transmitters

3

Press and release the TEST button to index to the next position.
1 2 2 will remain, and the fourth position will be blinking.

Use the s up and t down buttons to select 0.

Press and release the TEST button to proceed to the passcode
configuration.

Note: If an incorrect passcode was entered, the gauge will exit
to the normal operating mode.

The upper display section will indicate the user modifiable
passcode. The lower section will display UDPCD.

To change the user modifiable passcode, press and release
either the s up or t down button.

The first character of the passcode will begin to blink.

Use the s up and t down buttons to set the blinking character
to the desired value, then press and release the TEST button to
move to the next character.

Repeat for each character position.

When the user modifiable passcode is displayed with no
characters blinking, press and release the TEST button to save
the new passcode and restart the gauge.

Note: To make a correction to the new passcode before saving
and restarting, press either the s up or t down button to return
to the UDPCD code entry sequence.

Configuration Mode

Press and hold the s up button and then press the TEST button
until the upper display indicates CFG.

Enter the passcode as outlined in the the Passcode Entry
section.

After the correct passcode is entered, press and release the
TEST button to configure °F/°C, upscale/downscale burnout, 4
mA temperature, and 20 mA temperature.

Configuring Deg C or Deg F

The upper display section will be blank, and the lower section
will display either DEG C or DEG F.

To change from °C to °F, press and release the s up button.
The lower section of the display will change to DEG F.

To change from °F to °C, press and release the t down button.
The lower section of the display will change to DEG C.

Note: whether or not a change is made, the Test value will be
reset to 0.0°C or to 32.0°F.

Press and release the TEST button to move on to the next
parameter.

Configuring Upscale or Downscale Burnout

The upper display section will be blank, and the lower section
will display either DN BO or UP BO.

To change from downscale burnout to upscale burnout, press
and release the s up button. The lower section of the display
will change to UP BO.

To change from upscale burnout to downscale burnout, press
and release the t down button. The lower section of the display
will change to DN BO.

Press and release the TEST button to move on to the next
parameter.

Configuring Range Lower Limit

The upper display section will indicate the temperature
corresponding to a loop current of 4 mA. The lower section will
display RNGLO.

To change the temperature corresponding to a loop current of
4 mA, use the s up and the t down buttons to set the desired
value.

Press and release the TEST button to move on to the next
parameter.

Configuring Range Upper Limit

The upper display section will indicate the temperature
corresponding to a loop current of 20 mA. The lower section
will display RNGHI.

To change the temperature corresponding to a loop current of
20 mA, use the s up and the t down buttons to set the desired
value.

Exiting the Configuration Mode

Press and release the TEST button to save the configuration
parameters and restart the gauge.

The configuration parameters will not be saved if the procedure
is interrupted before completion.

TEST Button

When the front-panel TEST button is held depressed, the
display and loop current are switched, independent of the
temperature, to a test level determined by the setting of the
Test adjustment.

To set the test output level, press and hold the front-panel
TEST button and press the s up or t down button to adjust the
test output to the desired temperature setting. This setting is
stored in non-volatile memory.

Calibration

The PRTXD is factory calibrated and there is generally no
need to alter calibration settings. Calibration should only be
attempted if the user has access to a temperature reference of
known accuracy.

The quality of the calibration is only as good as the accuracy
of the calibration equipment and ideally should be at least four
times the unit’s accuracy.

Entering Calibration Mode

While pressing and holding the t down button, press the TEST
button to enter the calibration mode.

The upper section of the display will indicate CAL.

Enter the passcode as outlined in the the Passcode Entry
section.

After the correct passcode is entered, press and release the
TEST button to continue with calibration procedures.

Loop Calibration

Upon successful passcode entry, the upper segments of the
display will indicate the RTD probe temperature.

The lower segments of the display will alternate between CAL
and either DEG C or DEG F. The loop current will correspond to
the RTD probe temperature.

Note: To store the calibration parameters and exit calibration
mode at any time, press and hold the TEST button until the
display indicates - - - -.

The loop current calibration procedure coordinates the
loop current to the display indication, and is performed
independently of applied temperature. It requires a direct
physical measurement of the loop current.

4 mA Loop Current

Press the TEST button and release it when the display indicates
LCAL.

If the TEST button is held for longer than 2 seconds, the display
will indicate - - - - and the gauge will exit the calibration mode
when all buttons are released.

The upper display segments will indicate the preconfigured
temperature corresponding to a 4 mA loop current. The lower
display segments will alternate between CAL and 4 MA.

Use the s up and t down buttons to adjust the actual loop
current to 4 mA.

Note: Only the loop current will change. The upper display
segments will continue to indicate the preconfigured
temperature.

20 mA Loop Current

Press the TEST button and release it when the display indicates
HCAL.

If the TEST button is held for longer than 2 seconds, the display
will indicate - - - - and the gauge will exit the calibration mode
when all buttons are released.

The upper display segments will indicate the preconfigured
temperature corresponding to a 20 mA loop current.

The lower display segments will alternate between CAL and
20 MA.

Use the s up and t down buttons to adjust the actual loop
current to 20 mA.

Note: Only the loop current will change. The upper display
segments will continue to indicate the preconfigured
temperature.

Temperature Indication & Output Calibration

The temperature calibration procedure simultaneously adjusts
both the display indication and the loop current to correspond
to the actual applied temperature.

If the calibration is to be performed using an RTD simulator,
open the rear cover of the enclosure, disconnect the RTD probe
at the connector on the circuit board, and connect the simulator
in its place.

Ice-Point Calibration

Press the TEST button and release it when the display indicates
CAL.

If the TEST button is held for longer than 2 seconds, the display
will indicate - - - - and the gauge will exit the calibration mode
when all buttons are released.

Apply 0.0°C or 32.0°F to the RTD using a temperature bath
with a known accurate reference thermometer. The lower
display segments will alternate between CAL and DEG C or
DEG F.

Use the s up and t down buttons to adjust the upper display
segments to indicate 0.0°C or 32.0°F or a reading equal to the
reference thermometer.

Span Calibration

Apply full-scale temperature to the RTD. The lower display
segments will alternate between CAL and DEG C or DEG F.

Use the s up and t down buttons to adjust the upper display
segments to indicate the applied temperature value.

To store the calibration parameters and exit calibration mode,
press and hold the TEST button until the display indicates

- - - - .

WARRANTY/DISCLAIMER

OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and workmanship for a
period of 13 months from date of purchase. OMEGA’s WARRANTY adds an additional one (1) month
grace period to the normal one (1) year product warranty to cover handling and shipping time. This
ensures that OMEGA’s customers receive maximum coverage on each product.

If the unit malfunctions, it must be returned to the factory for evaluation. OMEGA’s Customer Service
Department will issue an Authorized Return (AR) number immediately upon phone or written request.
Upon examination by OMEGA, if the unit is found to be defective, it will be repaired or replaced at no
charge. OMEGA’s WARRANTY does not apply to defects resulting from any action of the purchaser,
including but not limited to mishandling, improper interfacing, operation outside of design limits,
improper repair, or unauthorized modification. This WARRANTY is VOID if the unit shows evidence of
having been tampered with or shows evidence of having been damaged as a result of excessive corrosion;
or current, heat, moisture or vibration; improper specification; misapplication; misuse or other operating
conditions outside of OMEGA’s control. Components in which wear is not warranted, include but are not
limited to contact points, fuses, and triacs.

OMEGA is pleased to offer suggestions on the use of its various products. However,
OMEGA neither assumes responsibility for any omissions or errors nor assumes liability for
any damages that result from the use of its products in accordance with information provided
by OMEGA, either verbal or written. OMEGA warrants only that the parts manufactured by the
company will be as specified and free of defects. OMEGA MAKES NO OTHER WARRANTIES OR
REPRESENTATIONS OF ANY KIND WHATSOEVER, EXPRESSED OR IMPLIED, EXCEPT THAT OF
TITLE, AND ALL IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. LIMITATION OF
LIABILITY: The remedies of purchaser set forth herein are exclusive, and the total liability of
OMEGA with respect to this order, whether based on contract, warranty, negligence,
indemnification, strict liability or otherwise, shall not exceed the purchase price of the
component upon which liability is based. In no event shall OMEGA be liable for
consequential, incidental or special damages.

CONDITIONS: Equipment sold by OMEGA is not intended to be used, nor shall it be used: (1) as a “Basic
Component” under 10 CFR 21 (NRC), used in or with any nuclear installation or activity; or (2) in medical
applications or used on humans. Should any Product(s) be used in or with any nuclear installation or
activity, medical application, used on humans, or misused in any way, OMEGA assumes no responsibility
as set forth in our basic WARRANTY/DISCLAIMER language, and, additionally, purchaser will indemnify
OMEGA and hold OMEGA harmless from any liability or damage whatsoever arising out of the use of the
Product(s) in such a manner.

RETURN REQUESTS/INQUIRIES

Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department.
BEFORE RETURNING ANY PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN AUTHORIZED
RETURN (AR) NUMBER FROM OMEGA’S CUSTOMER SERVICE DEPARTMENT (IN ORDER TO AVOID
PROCESSING DELAYS). The assigned AR number should then be marked on the outside of the return
package and on any correspondence.

The purchaser is responsible for shipping charges, freight, insurance and proper packaging to prevent
breakage in transit.

FOR WARRANTY RETURNS, please have the
following information available BEFORE contacting
OMEGA:

1. Purchase Order number under which the product
was PURCHASED,

2. Model and serial number of the product under
warranty, and

3. Repair instructions and/or specific problems

relative to the product.

OMEGA’s policy is to make running changes, not model changes, whenever an improvement is possible. This affords
our customers the latest in technology and engineering.

OMEGA is a registered trademark of OMEGA ENGINEERING, INC.
© Copyright 2017 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied, photocopied,

reproduced, translated, or reduced to any electronic medium or machine-readable form, in whole or in part, without the
prior written consent of OMEGA ENGINEERING, INC.

FOR NON-WARRANTY REPAIRS,
OMEGA for current repair charges. Have
the following information available BEFORE
contacting OMEGA:

1. Purchase Order number to cover the COST
of the repair,

2. Model and serial number of the product, and

3. Repair instructions and/or specific problems
relative to the product.

consult