Omega Products PX2088 Installation Manual

User’s Guide

Model PX2088 Pressure Transmitter

http://www.omega.com

e-mail: [e-mail]

Pressure Transmitter

PX2088

OMEGAnet® On-Line Service Internet e-mail
http://www.omega.com [e-mail]

Servicing North America:

USA: One Omega Drive, Box 4047
ISO 9001 Certified Stamford, CT 06907-0047
Tel: [phone] FAX: [phone]
e-mail: [e-mail]
Canada: 976 Bergar

Laval (Quebec) H7L 5A1
Tel: [phone] FAX: [phone]
e-mail: [e-mail]

For immediate technical or application assistance:

USA and Canada: Sales Service: 1-800-826-6342 / 1-800-TC-OMEGASM
Customer Service: 1-800-622-2378 / 1-800-622-BESTSM
Engineering Service: 1-800-872-9436 / 1-800-USA-WHENSM
TELEX: 996404 EASYLINK: 62968934 CABLE: OMEGA
Mexico and
Latin America: Tel: [phone] FAX: [phone]

En Espan˜ol: (95) 203-359-7803 e-mail: [e-mail]

Servicing Europe:

Benelux: Postbus 8034, 1180 LA Amstelveen, The Netherlands
Tel: [phone] FAX: [phone]

Toll Free in Benelux: 0800 0993344

e-mail: [e-mail]
Czech Republic: ul. Rude armady 1868, 733 01 Karvina-Hranice
Tel: [phone] FAX: [phone]

Toll Free: 0800-1-66342 e-mail: [e-mail]
France: 9, rue Denis Papin, 78190 Trappes
Tel: [phone] FAX: [phone]
Toll Free in France: 0800-4-06342

e-mail: [e-mail]
Germany/Austria: Daimlerstrasse 26, D-75392 Deckenpfronn, Germany
Tel: [phone] FAX: [phone]
Toll Free in Germany: 0130 11 21 66

e-mail: [e-mail]
United Kingdom: One Omega Drive, River Bend Technology Centre
ISO 9002 Certified Northbank, Irlam, Manchester

M44 5EX, England

Tel: [phone] FAX: [phone]

Toll Free in the United Kingdom: 0800-488-488

e-mail: [e-mail]

It is the policy of OMEGA to comply with all worldwide safety and EMC/EMI regulations that apply. OMEGA is constantly pursuing certification of
its products to the European New Approach Directives. OMEGA will add the CE mark to every appropriate device upon certification.

The information contained in this document is believed to be correct, but OMEGA Engineering, Inc. accepts
no liability for any errors it contains, and reserves the right to alter specifications without notice.
WARNING: These products are not designed for use in, and should not be used for, patient-connected applications.

Table of Contents

SECTION 1
Introduction

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Safety Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Safety Notice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

Models Covered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

Using This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

SECTION 2
Commissioning the Smart Transmitter

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Safety Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Commission: On the Bench or In the Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

Set up the Transmitter and the Communicator . . . . . . . . . . . . . . . . . . . . . 2-2

Review Configuration Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Check Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Process Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

Basic Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Tag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Output Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-4

Rerange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-5

Damping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Detailed Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Meter Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Burst Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-6

Save, Recall, or Clone Configuration Data . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

Enable or Disable Local Span and Zero Buttons . . . . . . . . . . . . . . . . . . . . . 2-7

Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8

Calibration Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-8

Sensor Trim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9

Output Trim . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11

Diagnostics and Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-12

Multidrop Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13

i

SECTION 3
Commissioning the Analog Transmitter

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

Safety Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

Commission: On the Bench or In the Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

Test Terminals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

Zero and Span Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

Selector Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

Potentiometer Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Setting the Zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Setting the Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5

SECTION 4
Installation

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

Safety Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

Installation Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

Model PX2088 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

Wiring Connections PX2088 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10

Failure Mode and Security Jumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11

Failure Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11

Transmitter Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

Zero and Span Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

Rerange Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13

SECTION 5
Troubleshooting

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

ii

SECTION 6
Spare Parts and Ordering

Spare Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

SECTION 7
LCD Meter

LCD Meter for Smart Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1

Diagnostic Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-2

LCD Meter for Analog Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4

Diagnostic Message Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5

Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5

Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-6

Positioning the Decimal Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7

Scaling the Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-7

iii

APPENDIX A
Model HC275 HART
Communicator

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Safety Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Menu Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2

Fast Key Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3

iv

SECTION

1

Introduction

OVERVIEW

This section contains general transmitter safety information, a brief description of
each model covered in this manual, and a summary of each of each section.

SAFETY MESSAGES

Procedures and instructions in this manual may require special precautions to
ensure the safety of the personnel performing the operations.

SAFETY NOTICE

The following performance limitations may inhibit efficient or safe operation. Critical
applications should have appropriate diagnostic and backup systems in place.

Pressure transmitters contain an internal fill fluid. It is used to transmit the process pressure
through the isolating diaphragms to the pressure sensing element. In rare cases, oil leak paths
in oil-filled pressure transmitters can be created. Possible causes include: physical damage to
the isolator diaphragms, process fluid freezing, isolator corrosion due to an incompatible
process fluid, etc.

A transmitter with an oil fill fluid leak can continue to perform normally for a period of time.
Sustained oil loss will eventually cause one or more of the operating parameters to exceed
published specifications while a small drift in operating point output continues. Symptoms of
advanced oil loss and other unrelated problems include:

nSustained drift rate in true zero and span or operating point output or both
nSluggish response to increasing or decreasing pressure or both
nLimited output rate or very nonlinear output or both
nChange in output process noise
nNoticeable drift in operating point output
nAbrupt increase in drift rate of true zero or span or both
nUnstable output
nOutput saturated high or low

1-1

MODELS COVERED

Model PX2088 Smart and Analog Absolute or Gage Pressure Transmitter

measures absolute or gage pressure ranges from 0–1 to 0–4,000 psi
(0–6.9 to 0–27579 kPa) using a patented piezoresistive silicon sensor.
Mounts directly to the process pipe or to the optional mounting bracket.

USING THIS MANUAL

This manual provides information for the Omega Model PX2088
Pressure Transmitter. It is organized into the following sections:

Section 2 Commissioning the Smart Transmitter

This section provides information on commissioning and operating the Model PX2088
Smart Pressure Transmitter. Information is also included on software functions,
configuration parameters, and on-line variables.

Section 3 Commissioning the Analog Transmitter

This section provides information on commissioning and operating the Model PX2088
Analog Pressure Transmitter.

Section 4 Installation

This section provides installation procedures, wiring diagrams, and information
about transmitter load limitations and power supply requirements.

Section 5 Troubleshooting

This section provides basic troubleshooting suggestions to help solve the most
common operating problems.

Section 6 Reference Data

This section provides reference data including ambient temperature effects, spare
parts, and typical transmitter model structures.

Secton 7 LCD Meter

This section provides installation and operation information for the optional LCD
Meter.

Appendix B HART Communicator

menu tree and fast key sequences for HART Communicator

1-2

SECTION

2 Commissioning the Smart

Transmitter

OVERVIEW

This section contains information regarding commissioning the transmitter.
Commissioning involves reviewing configuration data, setting the 4 and 20 mA
points, configuring the transmitter to recognize accessories such as a LCD meter,
and testing the transmitter output.

SAFETY MESSAGES

This section contains procedures that require connecting a communicator to the
transmitter, or making connections in an explosive atmosphere. The following safety
messages apply to all procedures throughout this section requiring cover removal
and communicator connection to the transmitter terminal block. Keep the following
safety messages in mind whenever you perform an operation requiring cover
removal or the connection of a communicator to a measurement loop.

Warnings

Explosions could result in death or serious injury:

nDo not remove the transmitter covers in explosive atmospheres

when the circuit is alive.

nBefore connecting a HART-based communicator in an explosive atmosphe re,

make sure the instruments in the loop are installed in accordance with
intrinsically safe or non-incendive field wiring practices.

nBoth transmitter covers must be fully engaged to meet

explosion-proof requirements.

High voltage that may be present on leads could cause electrical shock:

nAvoid contact with leads and terminals.

2-1

COMMISSION: ON THE BENCH OR IN THE LOOP

Commission the Model PX2088 Smart Transmitter before or after installation.
It may be useful to commission the transmitter on the bench before
installation to ensure proper operation, to familiarize yourself with transmitter
functionality, and to avoid exposing the transmitter electronics to the plant
environment. Commissioning consists of reviewing configuration data, setting
output units, setting the 4 and 20 mA points, configuring the transmitter for any
non-standard accessories or functions, and testing the transmitter output.

Set up the Transmitter and the Communicator

To configure the transmitter on the bench, connect the transmitter and the
communicator as shown in Figure 2-1. To power the transmitter you will need a
power supply capable of providing 10.5 to 36.0 V dc and a meter to measure output
current. To enable communication, a resistance of at least 250 ohms must be present
between the communicator loop connection and the power supply. You can connect the
communicator leads at any termination point in the signal loop, but it is most
convenient to connect them to the terminals labeled “COMM” on the terminal block.

After you con nec t th e b ench equipm e nt a s s h ow n in Figure 2-1, turn on the
communicator by pressing the ON/OFF key. The communicator will search for a
HART-compatible device and will indicate that the connection is made. If the
connection is not made, the communicator will indicate that no device was found.

FIGURE 2-1. Connecting a Communicator to a Transmitter Loop

RL≥ 250 V

Power
Supply

The signal loop may be grounded
at any single point in the loop, or
may be left ungrounded

2088S-2088C02C

If the communicator lacks the device driver for the PX2088 Smart, the transmitter will
be identified as “GENERIC” by the communicator. Basic configuration functions are
still possible, but many advanced configuration functions are not possible when the
communicator is in this mode. Contact Omega customers service for assistance
in obtaining the PX2088 Smart device driver for the HART Communicator.

2-2

FIGURE 2-2. HART Communicator ScreenWithout Model PX2088 S ma rt De vice Drive r.

Generic

Online
1 Device Setup
2 PV 100.00 inH2O
3 AO 20.00 mA
4 LRV 0.00 inH2O
5 URV 100.00 inH2O

REVIEW CONFIGURATION DATA

Review all of the factory-set configuration data to ensure that is reflects the needs of
your application before operating the transmitter in an actual installation.

Review

HART Fast Keys

Review the transmitter configuration parameters set at the factory to ensure
accuracy and compatibility with your particular application. After activating the
review function, scroll through the data list to check each variable. Refer to “Basic
Setup” in this section of the manual if a change to the transmitter configuration data
is necessary.

1, 5

CHECK OUTPUT

Before performing other transmitter on-line operations, review the digital output
parameters to ensure that the transmitter is operating properly and is configured to
the appropriate process variables.

Process Variables

HART Fast Keys

The process variables for the Model PX2088 Smart provide the transmitter output,
and are continuously updated. The Process Variable menu displays the following
process variables:

nPressure
nPercent Range
nAnalog Output

1, 1

2-3

BASIC SETUP

From the Basic Setup menu you can configure the transmitter for certain basic
variables. In many cases, all of these variables are pre-configured at the factory.
Configuration may be required if your transmitter is not configured or if the
configuration variables need revision.

Tag

HART Fast Keys

1, 3, 1

The Tag variable is the easiest way to identify and distinguish between transmitters
in multi-transmitter environments. Use this variable to label transmitters
electronically according to the requirements of your application. The tag you define
is automatically displayed when a HART-based communicator establishes contact
with the transmitter at power-up. The tag may be up to eight characters long and
has no impact on the primary variable readings of the transmitter.

Output Units

HART Fast Keys

The Unit command sets the desired primary variable units. Set the transmitter
output to one of the following engineering units:

ninH

O

2

ninHg
nftH

O

2

nmmH

O

2

npsi
nbar
nmbar
nInH

O @ °4 C

2

NOTE

Output units is the only variable which must be sent separately from all other
variable configurations. After changing units, press SEND (F2) so the
microprocessor will recalculate the associated variables (4–20 mA points, for
example). The Model PX2088 Smart recalculates all variables that depend on units.
After the transmitter recalculates the variables, you may change any of the
remaining parameters.

1, 3, 3

ng/cm
nkg/cm
nPa
nkPa
ntorr
natm
nmmH

2

2

O @ °4 C

2

2-4

Rerange

HART Fast Keys

1, 3, 3

The Range Values command sets the 4 and 20 mA points (lower and upper range
values). Setting the range values to the limits of expected readings maximizes
transmitter performance; the transmitter is most accurate when operated within the
expected pressure ranges for your application. In practice, you may reset the
transmitter range values as often as necessary to reflect changing process
conditions.

You may use one of three methods to rerange the transmitter. Each method is
unique; examine all three closely before deciding which method to use.

NOTE

Regardless of the range points, the Model PX2088 Smart will measure and report all
readings within the digital limits of the sensor. For example, if the 4 and 20 mA
points are set to 0 and 10 inH
it digitally outputs the 25 in H
However, there may be up to ±5.0% error associated with output outside of the range

O, and the transmitter detects a pressure of 25 inH2O,

2

O reading and a 250% percent of span reading.

2

points.

Method 1:Rerange Using the Communicator

Reranging using only the communicator is the easiest and most popular way to
rerange the transmitter. This method changes the values of the analog 4 and 20
mA points independently without a pressure input.

To rerange using only the communicator enter the fast-key sequence above, select
1 Keypad input, and follow the on-line instructions. Or enter the values directly
from the HOME screen.

Method 2:Rerange Using the Communicator and a Pressure Source or Process

Pressure

Reranging using the communicator and a pressure source or process pressure is a
way of reranging the transmitter when specific 4 and 20 mA points are not known.
This method changes the values of the analog 4 and 20 mA points. When you set
the 4 mA point the span is maintained; when you set the 20 mA point the span
changes.

To rerange using the communicator and a pressure source or process pressure
enter the fast-key sequence above, select 2 Apply values, and follow the on-line
instructions.

Method 3:Rerange Using the Local Zero and Span Buttons

and a Pressure Source or Process Pressure

Reranging using the local zero and span adjustments and a pressure source is a
way of reranging the transmitter when specific 4 and 20 mA points are not known
or a communicator is not available. When you set the 4 mA point the span is
maintained; when you set the 20 mA point the span changes.

To rerange using the zero and span adjustments, refer to “Rerange Procedure” on
page 4-13.

2-5

Damping

HART Fast Keys

The Damping command changes the response time of the transmitter to smooth
variations in output readings caused by rapid changes in input. Determine the
appropriate damping setting based on the necessary response time, signal stability,
and other requirements of the loop dynamics of your system. The default damping
value is 0.50 seconds and can be reset in fixed increments of 0.05, 0.10, 0.20, 0.40,

0.80, 1.60, 3.20, 6.40, 12.8, or 25.6 seconds.

1. 3. 6

DETAILED SETUP

Meter Setup

HART Fast Keys

The Meter Type command allows you to configure the transmitter for use with an
LCD meter. Transmitters shipped without meters are set to “NONE.” Change the
meter settings as often as necessary to reflect changing process or application
conditions. To change the meter settings, and thereby configure the transmitter to
recognize the LCD meter, perform the following procedure.

1.Select 1 Device setup, 4 Detailed setup, 3 Output condition, 4 Meter options to
prepare to change the meter settings.

2.Select the appropriate variable configuration from the Meter options screen,
and press enter.

1, 4, 3, 4

NOTE

Selecting “None” from the meter type screen will disable the meter.

3.Select SEND to download the new meter configuration information to the
transmitter.

For a more detailed description of the LCD meter features and diagnostic messages,
refer to Section 7 LCD Meter.

Burst Mode

HART Fast Keys

Burst Mode sets the transmitter to maintain digital contact with a Digital Control
System that has custom software to support burst mode. When the Model PX2088
Smart is configured for burst mode, it provides faster digital communication from
the transmitter to the control system by eliminating the time required for the control
system to request information from the transmitter.

1, 4, 3, 4, 3

2-6

Burst mode is compatible with use of the analog signal. Because HART® protocol
features simultaneous digital and analog data transmission, the analog value can
drive other equipment in the loop while the control system is receiving the digital
information. Burst mode applies only to the transmission of dynamic data (pressure
and temperature in engineering units, pressure in percent of range, and/or analog
output in mA or V), and does not affect the way other transmitter data is accessed.

Access to information other than dynamic transmitter data is obtained through the
normal poll/response method of HART communication. A HART-based
communicator or the control system may request any of the information that is
normally available while the transmitter is in burst mode. Between each message
sent by the transmitter, a short pause allows the HART-based communicator or a
control system to initiate a request. The transmitter will receive the request, process
the response message, and then continue “bursting” the data approximately three
times per second.

Save, Recall, or Clone Configuration Data

HART Fast Keys

Data that was entered off-line can be stored in the communicator memory and
downloaded to other transmitters later. Data also can be copied from a transmitter in
order to be sent to other transmitters in a process known as “cloning”. This is
especially useful if you work with a large number of transmitters that require the
same configuration data.

left arrow, 3 (note)

Enable or Disable Local Span and Zero Buttons

HART Fast Keys

The Local Keys command allows you to enable or disable the local span and zero
buttons. Disabling the local keys will prevent unauthorized reranging using the span
and zero buttons, but will not prevent reranging using the communicator . To prevent
all changes to the configuration data, use the transmitter security jumper (see
“Transmitter Security” on page 4-12).

1, 4, 4, 1, 7

2-7

CALIBRATION

Calibrating the transmitter increases the precision of your measurement system.
You may use one or more of a number of trim functions when calibrating.

To understand the trim functions, it is necessary to understand that smart
transmitters operate differently from analog transmitters. An important difference is
that smart transmitters are fa ctory -c haracte rized; they are shipped with a standard
sensor curve stored in the transmitter firmware. In operation, the transmitter uses
this information to produce a process variable output, in engineering units,
dependent on the sensor input. The trim functions allow you to make corrections to
the factory-stored characterization curve by digitally altering the transmitter’s
interpretation of the sensor input.

The trim functions should not be confused with the rerange functions. Although the
rerange command matches a sensor input to a 4–20 mA output—as in conventional
calibration—it does not affect the transmitter’s interpretation of the input.

Calibration Overview

Complete calibration of the Model PX2088 Smart Pressure Transmitter involves one or
more of the following tasks:

Configure the Analog Output Parameters

nSet Process Variable Units (Page 2-3)
nRerange (Page 2-5)
nSet Output Type (Page 2-4)
nSet Damping (Page 2-6)

Calibrate the Sensor

nFull Trim (Page 2-10)
nZero Trim (Page 2-10)

Calibrate the 4–20 mA Output

nDigital to Analog Trim (Page 2-11) or
nScaled Digital to Analog Trim (Page 2-12)

Figure 2-3 illustrates the Model PX2088 Smart transmitter data flow. This data flow
can be summarized in four major steps:

1.A change in pressure is measured by a change in the sensor output (Sensor
Signal).

2.The sensor signal is converted to a digital format that can be understood by
the microprocessor (Analog-to-Digital Signal Conversion).

3.Corrections are performed in the microprocessor to obtain a digital
representation of the process input (Digital PV).

4.The Digital PV is converted to an analog value
(Digital-to-Analog Signal Conversion).

2-8

FIGURE 2-3. Transmitter Data Flow
with Calibration Options.

(Transmitter Ranged 0 to 100 inH

2

Transmitter Electronics Module

Analog-to-

Digital Signal

Conversion

3 4

Microprocessor

Digital PV

O)

2

Digital-to-Analog

Signal Conversion

Analog Output

1

100 inH2O

Sensor Signal

Input Device

If readings do not
match perform
sensor trim

NOTES

1)Value on PV line should equal
the input pressure

2)Value on AO line should equal the
output device reading

HART Communications

PX2088S:PT-4763

Online
1 Device Setup

2 PV 100.00 inH2O

3 AO 20.00 mA
4 LRV 0.00 inH2O
5 URV 100.00 inH2O

20.00 mA

Output Device

If readings do

not match

perform

output trim

Deciding Which Trim
Procedure to Use

To decide which trim procedure to use, you must first determine whether the analog­to-digital section or the digital-to-analog section of the transmitter electronics is in
need of calibration. To do so, refer to Figure 2-3 and perform the following procedure:

1.Connect a pressure source, a HART communicator, and an output device to
the transmitter.

2.Establish communication between the transmitter and the communicator.

3.Apply the desired 20mA point pressure (100 in H2O, for example).

4.Compare the applied pressure to the Process Variable (PV) line on the
Communicator Online Menu. If the PV reading on the communicator does not
match the applied pressure, and you are certain your test equipment is
accurate, perform a sensor trim.

5.Compare the Analog Output (AO) line on the communicator online menu to
the digital readout device. If the AO reading on the communicator does not
match the digital readout device, and you are certain your test equipment is
accurate, perform an output trim.

Sensor Trim

You can trim the sensor using either the full trim or the zero trim function. The trim
functions vary in complexity, and their use is application-dependent. Both alter the
transmitter’s interpretation of the input signal.

2-9

A zero trim is a single-point adjustment. It is useful for compensating for mounting
position effects, and can be performed with the transmitter installed or from the
bench. Since this correction maintains the slope of the characterization curve, it
should not be used in place of a full trim over the full sensor range.

A full trim is a two-point sensor calibration where two end-point pressures are
applied, and all output is linearized between them. Y ou should always adjust the low
trim value first to establish the correct offset. Adjustment of the high trim value
provides a slope correction to the characterization curve based on the low trim value.
The factory-established characterization curve is not changed by this procedure. The
trim values allow you to optimize performance over your specified measuring range
at the calibration temperature.

Zero Trim

HART Fast Keys

1, 2, 3, 3, 1

To calibrate the sensor using the zero trim function, perform the following procedure.

1. Vent the transmitter and attach a communicator to the measurement loop.

2. From the communicator main menu select 1 Device setup,
2 Diagnostics and service, 3 Calibration, 3 Sensor trim, 1 Zero trim to prepare
to adjust the zero trim.

NOTE

The transmitter must be within 3% of true zero (zero based) in order to calibrate
using the zero trim function.

3. Follow the commands provided by the communicator to complete the
adjustment of the zero trim.

Full Trim

HART Fast Keys

1, 2, 3, 3

To calibrate the sensor using the full trim function, perform the following procedure.

1. Assemble and power the entire calibration system including a transmitter,
communicator, power supply, pressure input source, and readout device.

NOTE

Use a pressure input source that is at least three times more accurate than the
transmitter, and allow the input pressure to stabilize for 10 seconds before entering
any values. If remote seals are used allow more time for the input pressure to
stabilize.

2. From the communicator main menu select 1 Device setup,
2 Diagnostics and service, 3 Calibration, 3 Sensor trim, 2 Lower sensor trim to
prepare to adjust the lower trim point.

2-10