Baker Hughes Druck 8000 Series User manual

Druck.com
8000/8100/8200/8300
Series
Trench Etched Resonant Pressure Sensor
Instruction Manual

Copyright 2010 Baker Hughes Company.
English–TERPS Instruction Manual | i
Safety
The manufacturer has designed this sensor to be safe when operated using the procedures
detailed in this manual. Do not use this sensor for any other purpose than that stated.
This publication contains operating and safety instructions that must be followed for safe
operation and to maintain the sensor in a safe condition. The safety instructions are either
warnings or cautions issued to protect the user and the equipment from injury or damage.
Use qualified1 personnel and good engineering practice for all procedures in this publication.
Toxic Materials
There are no known toxic materials used in this sensor.
Maintenance
The sensor must be maintained using the manufacturer’s procedures and these should be carried
out by authorized service agents or the manufacturer’s service departments.
Druck.com
For technical advice contact the manufacturer.
Symbols
Abbreviations
The following abbreviations are used in this manual.
WARNING Do not apply pressure greater than the maximum safe working
pressure to the sensor.
1 A qualified technician must have the necessary technical knowledge, documentation, special test
equipment and tools to carry out the required work on this equipment.
Symbol Description
This equipment meets the requirements of all relevant European safety directives. The
equipment carries the CE mark.
This symbol, in this manual, indicates a hazardous operation.
Do not dispose of this product as household waste. Use an approved organization that
collects and/or recycles waste electrical and electronic equipment. For more information,
contact one of these:
- Our customer service department: Druck.com
- Your local government office.

Copyright 2010 Baker Hughes Company.
ii | TERPS Instruction Manual–English
Note: Abbreviations are the same in the singular and plural.
Abbreviation Description
a Absolute
ASCII American Standard Code for Information Interchange
°C Degrees Celsius
atm Atmosphere
bps Bits per second
cmHg Centimetre of mercury
COSHH Control of Substances Hazardous to Health
CR Carriage return
dc Direct current
EEPROM Electrically Erasable Programmable Read Only Memory
EMC Electro-Magnetic Compatibility
FS Full-scale
ftH2O Feet of water
hPa Hecto Pascal
Hz Hertz
inH2O Inches of water
inHg Inch of mercury
kg Kilogram
kg/cm2Kilogram per centimetre squared
kg/m2Kilogram per metre squared
kHz Kilohertz
kPa Kilo Pascal
lb/ft2 Pounds per foot squared
LF Line feed
LSB Least Significant Bit
mA Milli Ampere
mbar Millibar
mbar a Millibar absolute
mH2O Metres of water
mHg Metre of mercury
mm Millimetre
mmH2O Millimetres of water
mmHg Millimetre of mercury
MPa Megapascal
MSB Most Significant Bit

Copyright 2010 Baker Hughes Company.
English–TERPS Instruction Manual | iii
MSDS Material Safety Data Sheet
MSL Local meteorological pressure
MΩ Mega ohm
n/a Not applicable
Pa Pascal
PIN Personal Identification Number
ppm Parts per million
psi Pound per square inch
QFE Field elevation
QFF Local station pressure, reduced to mean sea level
QNH Nautical height
RF Radio frequency
RPT Resonant Pressure Transducer
RS-232 ANSI TIA-232 communication standard
RS-485 ANSI TIA-485 communication standard
TERPS Trench Etched Resonant Pressure Sensor
TTL Transistor-Transistor Logic
USB Universal Serial Bus
V Volt
Abbreviation Description

Copyright 2010 Baker Hughes Company.
iv | TERPS Instruction Manual–English

Copyright 2010 Baker Hughes Company.
English–TERPS Instruction Manual | v
Contents
1. Introduction 1
1.1 Manufacturer 1
2. Description 1
2.1 Purpose 1
2.2 Technical Specifications 1
2.3 Design and Principle of Operation 1
2.3.1 TERPS 8XXX Models 1
2.3.2 RPS8100 Minicore Models 2
2.4 Markings 3
2.4.1 TERPS 8X00 Pressure Sensor 3
2.4.2 RPS8100 Minicore Pressure Sensor 3
3. Installation & Operation 3
3.1 General Requirements 3
3.2 Safety Measures 4
3.3 Connecting to a Pressure Source 5
3.3.1 Media Compatibility 6
3.3.2 Pressure Containment 6
3.4 Power Requirements 6
3.5 Software 6
3.5.1 USB Driver 6
3.5.2 LabVIEW Driver 7
3.5.3 Mobile Application 7
3.6 Maintenance 7
3.6.1 Visual Inspection 7
3.6.2 Cleaning 7
3.6.3 Adjustment 7
3.7 Returned Goods Procedure 7
3.7.1 Safety Precautions 8
3.7.2 Important Notice 8
3.8 Electromagnetic Compatibility 8
3.8.1 Power Supply and Metering 8
3.8.2 Cable Type 8
3.8.3 Earthing 9
4. RPS Pressure Measurement 9
4.1 Measuring the Frequency 9
4.2 Measuring the Diode Voltage 9
4.3 Calculating Pressure 9
4.4 Stored Coefficients 10
5. DPS Pressure Measurement 10
5.1 Serial Data Communications Settings 10
5.2 Applications 10
5.3 RS-485 Connections 11
5.4 RS-232 Connections 11
5.5 USB Connection 12

Copyright 2010 Baker Hughes Company.
vi | TERPS Instruction Manual–English
5.6 Measuring Pressure 12
5.7 Factory Defaults 12
6. Programming Guide 13
6.1 Command Summary 13
6.2 Communication Modes 14
6.2.1 Direct Mode 14
6.2.2 Addressed Mode 14
6.3 Command Syntax 14
6.3.1 Direct Mode Syntax 15
6.3.2 Addressed Mode Syntax 15
6.4 Measurement Commands 15
6.4.1 R - Get Reading 15
6.4.2 G - Get New Reading and Transmit 16
6.4.3 Z - Read Raw Data 16
6.5 Information Commands 16
6.5.1 I - Transducer Identity 16
6.6 General Set-up Commands 17
6.6.1 A - Auto-send Reading 17
6.6.2 N - Set Device (Transducer) Address 18
6.6.3 Q - Set Measurement Speed 19
6.6.4 U - Set Units 19
6.7 PIN Protected Set-up Commands 20
6.7.1 C - User Calibration 20
6.7.2 H - Change Slope 21
6.7.3 M - User Message 22
6.7.4 O - Communication Settings 23
6.7.5 P - Change PIN 24
6.7.6 S - Set Offset 25
6.8 Factory Commands - Query Only 25
6.8.1 E - Crystal Reference Frequency 25
6.8.2 L - Load Calibration Coefficients 26
6.8.3 T - Analogue/Digital Converter Set-up 26
6.8.4 V - Transducer Type and Settings 27
6.8.5 W - EEPROM Query 27
6.9 Error Messages 28
6.9.1 Incorrect User Command 28
6.9.2 Transducer Fault 28
Appendix A. Fault Finding 29
Appendix B. RPS EEPROM Format 31

Copyright 2010 Baker Hughes Company.
English–TERPS Instruction Manual | 1
1. Introduction
This manual is applicable to 8000 family pressure sensors consisting of the following product
series:
• [TERPS] 8000, 8100, 8200 and 8300
• RPS8100 Minicore
The original language of this manual is English.
1.1 Manufacturer
The identified manufacturer of this equipment is:
“Druck Limited”
Fir Tree Lane, Groby, Leicester, LE6 0FH, United Kingdom.
Telephone: [phone]; Fax: [phone]
Internet: Druck.com
2. Description
2.1 Purpose
The 8000 family pressure sensors use TERPS (trench etched resonant pressure sensor)
technology and are designed for continuous measurement and conversion of pressure into an
electronic output.
RPS 8XXX models produce a frequency and a diode voltage output. DPS 8XXX models include
a microprocessor to produce a serial digital output.
The sensors are of a modular design, the parameters of which are chosen by the customer at the
time of order.
2.2 Technical Specifications
The sensors are divided into two groups:
a. TERPS 8X00 Pressure Sensor
The sensor has a model number of the form '#PS 8###-T#-A#-C#-##-##'.
Refer to the appropriate 8000, 8100, 8200 or 8300 data sheet for technical specifications and
explanation of the sensor's model number.
Model numbers appended with a four or eight-digit alphanumeric string denote the use of a
customer-specific specification drawing indicating the use of additions or deviations to the
data sheet specification. Refer to the specification drawing if applicable.
b. RPS8100 Minicore Pressure Sensor
The sensor has a model number of the form 'RPS8100-###B'.
The sensor's model number is appended with a four or eight-digit alphanumeric string
indicating the appropriate product specification drawing number. Refer to the drawing for the
specifications of the product.
2.3 Design and Principle of Operation
2.3.1 TERPS 8XXX Models
The sensor consists of a pressure connector, pressure measuring module, a partially
encapsulated electronics module, and electrical connection facilities, structurally combined in a
cylindrical metal housing.
The pressure connector allows the sensor to be mounted to a pressurized vessel or pipework.

Copyright 2010 Baker Hughes Company.
2 | TERPS Instruction Manual–English
The pressure measuring module consists of a welded metal construction, featuring a metal
diaphragm* (providing a flexible barrier to harsh process media), a glass-to-metal seal (for
electrical connections) and a fluid filled* cavity containing a silicon-based micro-machined
resonant structure.
The electronics module is available in two primary variants:
a. DPS variants provide a digitally encoded signal derived from the measured frequency of the
resonant structure as it responds to applied pressure. A variety of digital encoding and
physical interface options are available.
b. RPS variants provide a square wave output with a frequency equal to that of the resonant
structure as it responds to applied pressure. An additional output (derived from the forward
voltage of a diode) provides a voltage responding to changes in temperature.
2.3.2 RPS8100 Minicore Models
The RPS8100 Minicore pressure sensor is designed to measure the pressure of non-condensing
dry gas.
The sensor consists of a pressure connector, a silicon-based micro-machined resonant structure
(directly exposed to the measured gas), an electronics module (not encapsulated), and electrical
connection facilities, structurally combined in a cylindrical metal housing.
The pressure connector allows the sensor to be mounted to a pressurized vessel or pipework.
The electronics module is housed in a compartment, separated from the external atmosphere by
glass-to-metal seals.
Low voltage electrical terminals are exposed at the rear of the compartment and are soldered to
a short length of cable for connection to the host equipment.
The sensor provides a square wave output with a frequency equal to that of the resonant structure
as it responds to applied pressure. An additional output (derived from the forward voltage of a
diode) provides a voltage responding to changes in temperature.
The pressure sensor is intended to be incorporated within an original equipment manufacturer's
host product, for which additional technical regulations and standards may be applicable.
* 80XX, 82XX and 83XX models only. 81XX models provide no harsh process media isolation.

Copyright 2010 Baker Hughes Company.
English–TERPS Instruction Manual | 3
2.4 Markings
2.4.1 TERPS 8X00 Pressure Sensor
The markings applied to the pressure sensors are in English, see Figure 1:
Figure 1: Identification, Electrical and Pressure Markings - TERPS 8X00
Other data is possible, which the manufacturer can reflect in the marking, if required by technical
documentation.
2.4.2 RPS8100 Minicore Pressure Sensor
The markings applied to the pressure sensors are in English, see Figure 2:
Figure 2: Identification, Electrical and Pressure Markings - RPS8100 Minicore
Other data is possible, which the manufacturer can reflect in the marking, if required by technical
documentation.
3. Installation & Operation
3.1 General Requirements
When the sensor is received, check for completeness.
1 Product name: 'TERPS 8#00'.
2 Product description: 'PRESSURE SENSOR'.
3 Model number - To identify the meaning, refer to the product data sheet. If the model number is followed
by four or eight numbers, '-####' or '-########', refer to the manufacturer's specification drawing
E-A3-#### or ########.
4 Serial number.
5 Pressure range limits and unit of measurement.
6 Power supply voltage range.
7 Output: 'TTL & DIODE', 'RS232', 'RS485', 'USB 2.0'.
8 Ambient temperature range.
9 Manufacturer's name and address.
1 Manufacturer's name.
2 Model number - The model number is followed by four or eight numbers, '-####' or '-########', refer to
the manufacturer's specification drawing E-A3-#### or ########.
3 Serial number.
4 Pressure range limits and unit of measurement.
5 Power supply voltage range.
CAUTION Until installation, keep the unit in the original container with all the
covers in position. The container and covers prevent contamination and
damage. When not in use, keep the connections clean at all times, and put the
covers on the open connections.
TERPS 8#00
PRESSURE SENSOR
S/N #######
### TO ### ### #
Supply: ### TO ### Vdc
Output: ######
Temp. Range: ### TO #### °C
DRUCK LTD. GROBY, LE6 0FH, UK
[1]
[2]
[3]
[4]
[5]
[6]
[9]
#PS 8###-T#-A#-C#-H#-##
[7]
[8]
DRUCK
RPS 8100-##B-######## S/N #######
### TO ### ### #
Supply: ### TO ### Vdc
[1]
[2] [3]
[4]
[5]

Copyright 2010 Baker Hughes Company.
4 | TERPS Instruction Manual–English
To identify the electrical and pressure connections, refer to the product data sheet or, if
applicable, the specification drawing.
Do not use force when installing the sensor. Do not tighten the sensor by rotating the housing.
For this purpose, a hexagon socket for the wrench is provided on the housing.
The ambient temperature and the process media to be measured must not exceed the ranges
specified in the sensor specification.
In the negative temperature range it is necessary to exclude the accumulation and freezing of
condensate in the working chambers and inside the connecting pipelines for gaseous media and
freezing, crystallization of the medium or crystallization from it, of the individual components for
liquid media.
The materials used for the primary enclosure and pressure bearing surfaces are identified in the
product data sheet or, if applicable, the specification drawing. Make sure that the materials are
applicable for the installation.
Before using the equipment, remove the plastic/rubber protection cap from the pressure
connector.
The 80XX, 82XX and 83XX are harsh media isolated product. Isolation is achieved by
hermetically sealing the sensor element, see Figure 3, in an oil filled chamber. The weight of this
oil gives a g sensitivity as a pressure offset error.
The 81XX is not a harsh media isolated product. The pressure media comes directly into contact
with the sensor element. Care must be taken to ensure the pressure media does not damage the
sensor element. There is negligible change in offset due to mounting position and vibration.
Figure 3: TERPS Sensor Element
To calibrate the 8XXX Series, the unit is mounted vertically with the pressure port at the lowest
point. Orientation other than this produces a pressure offset error as specified in the data sheet.
The error is most noticeable at lower pressure ranges.
Note: The g-sensitivity will also create an error in a high vibration environment and the unit should
be mounted accordingly.
3.2 Safety Measures
The operation of sensors in systems whose pressure may exceed the overload values specified
in the data sheet or customer-specific specification drawing is not allowed.

Copyright 2010 Baker Hughes Company.
English–TERPS Instruction Manual | 5
Connection and detachment of sensors from the mains supplying the pressure of the medium to
be measured must be done after the shutoff valve is closed from the process and the pressure in
the working chamber is made equal to atmospheric.
The connecting pipes must have a one-way slope (not less than 1:10) from the pressure collection
point up to the sensor, if the medium to be measured is gas, and down to the sensor if the medium
is liquid. If this is not possible, when measuring gas pressure at the lower points of the connecting
lines, it is necessary to install sludge vessels, and when measuring the liquid pressure at the
highest points, install gas collectors.
Selected devices for mounting sensors should be mounted on straight sections, at the maximum
possible distance from pumps, locking devices, elbows, expansion joints and other hydraulic
devices. It is especially not recommended to install sensors in front of the shut-off device if the
medium to be measured is liquid. If there are water hammer effects in the system, it is
recommended to use a sensor complete with a hydraulic shock dampener.
To reduce the temperature acting on the isolation diaphragm when measuring vapor pressure, it
is recommended to use impulse tubes. The impulse tube must first be filled with water.
Attach the equipment in a safe configuration that prevents unwanted stress (vibration, physical
impact, shock, mechanical and thermal stresses). Do not install the equipment where it can be
damaged by a material that causes corrosion. Provide additional protection for the equipment if
it may be damaged in service.
When installing power supply and signal wiring, the possibility of condensate entering the sensor
cable entry should be avoided.
3.3 Connecting to a Pressure Source
When mounting the sensor, seal the mating surfaces. Failure to properly seal may affect
performance or calibration accuracy.
Male threaded pressure connectors must not be sealed or constrained against the face at the
base of the thread. The forward cone or flat face should always be used as indicated below.
Depth versions should not be used at hyperbaric pressures above 70 bar (1000 psi),
approximately 700 m (2300 ft) of water.
98

Copyright 2010 Baker Hughes Company.
6 | TERPS Instruction Manual–English
3.3.1 Media Compatibility
The media compatibility of the sensors is shown in Table 1.
Note: Fluid classification complies with European Regulation (EC) No 1272/2008. Statements
comply with European Pressure Equipment Directive 2014/68/EU.
3.3.2 Pressure Containment
The pressure containment of the sensors is shown in Table 2.
3.4 Power Requirements
The sensor should be connected to a stable power supply. The power supply requirements are
shown in Table 3.
3.5 Software
3.5.1 USB Driver
Drivers for the USB sensor are available from FTDI and should auto-install in any Windows® or
Android™ operating system. The USB driver is available to download from the FTDI website:
http://www.ftdichip.com/FTDrivers.htm
Table 1: Media Compatibility
Product Pressure Range Media Compatibility
81XX 0 to 3.5 bar
0 to 50 psi
Non-condensing dry gases compatible with silicon
dioxide, fluorosilicone RV adhesive, stainless steel
316L and glass.
80XX 0 to 70 bar
0 to 1000 psi
Fluids compatible with stainless steel 316L and
Hastelloy C276.
82XX
83XX
0 to 70 bar
0 to 1000 psi
Fluids compatible with Hastelloy C276.
Table 2: Pressure Containment
Product Pressure Range Pressure Containment
81XX 0 to 3.5 bar
0 to 50 psi
7bar maximum
100 psi maximum
80XX
82XX
83XX
0 to 7 bar
0 to 100 psi
70 bar maximum
1000 psi maximum
>7 to 70 bar
>100 to 1000 psi
200 bar maximum
2900 psi maximum
Table 3: Power Supply Requirements
Product Supply Voltage (V dc) Supply Current
RPS Versions 6 to 28 3.5 mA nominal
20 mA peak
RS-485 and RS-232
Versions 11 to 28 16 mA nominal 32 mA peak
USB Version Supplied by USB host 40 mA nominal
100 mA peak

Copyright 2010 Baker Hughes Company.
English–TERPS Instruction Manual | 7
3.5.2 LabVIEW Driver
A National Instruments certified LabVIEW driver is available to download from the National
Instruments’ website:
http://sine.ni.com/apps/utf8/niid_web_display.model_page?p_model_id=30206
The driver includes a Virtual Instrument to discover a sensor’s address. Example code snippets
are supplied with the driver.
The LabVIEW driver is plug-and-play compatible with the USB sensor. A USB to RS-485 adapter,
or a USB to RS-232 adapter, can be used to communicate with the RS-485 and RS-232 sensors.
3.5.3 Mobile Application
A TERPS mobile application for Android™ is available for free download from Google Play™. The
TERPS application displays pressure from any USB TERPS sensor.
Barometric TERPS sensors can optionally display the following aeronautical parameters: QFE,
QNH, QFF and MSL.
3.6 Maintenance
3.6.1 Visual Inspection
Inspect the product for damage and corrosion. Any damage to the product must be assessed. If
the housing is no longer sealed against water and/or dust, the product must be replaced.
3.6.2 Cleaning
Clean the case with a damp lint-free cloth and mild detergent.
If the product has been in contact with hazardous or toxic materials, obey all the applicable
Control of Substances Hazardous to Health (COSHH) or Material Safety Data Sheet (MSDS)
references and precautions when handling.
3.6.3 Adjustment
For some models, the Output Calibration, Full-Scale and Offset settings can be adjusted. For
instructions see Chapter 6, “Programming Guide,” on page 13.
Note: Druck can provide a calibration service that is traceable to international standards.
3.7 Returned Goods Procedure
To repair or calibrate the sensor, return it to the applicable Druck Service Department.
Please contact our Service Department, and get a Return Authorization number.
Please supply these details:
• Product (e.g. TERPS 8200 Pressure Sensor)
• Pressure range
• Serial number
• Details of defect / work to be undertaken
• Calibration traceability requirements
WARNING High pressures and temperatures are dangerous and can cause
injury (Refer to pressure limits in the sales data sheet). Be careful when working
on components connected to lines that have high pressures and heat. Use the
applicable protection and obey all safety precautions.
WARNING Output Calibration, Full-Scale and Offset adjustment may be
subject to state requirements for verification of metrological equipment.

Copyright 2010 Baker Hughes Company.
8 | TERPS Instruction Manual–English
• Operating conditions
3.7.1 Safety Precautions
To prevent possible injury when we receive the product, you must also tell us if the product has
been in contact with hazardous or toxic materials. Please supply the applicable Control of
Substances Hazardous to Health (COSHH) or Material Safety Data Sheet (MSDS) references
and precautions.
3.7.2 Important Notice
Service or calibration by unauthorized sources will affect the warranty and may not guarantee
further performance.
3.8 Electromagnetic Compatibility
The pressure sensor complies with the European Electromagnetic Compatibility Directive
2014/30/EU.
When appropriately installed the sensors meet and exceed the Commercial and Industrial
specifications indicated in Table 4:
3.8.1 Power Supply and Metering
The quality of the power supply and monitoring equipment will directly affect the EMC
performance of the entire system. Since “Druck Limited” has no control over the installation of the
sensor it must remain the responsibility of the user to ensure that the EMC performance of the
system is adequate.
To maintain good immunity from electromagnetic disturbances present on the system power
supply, the power supply should filter any transient interference from the incoming line and
present a clean regulated DC supply to the sensor. The monitoring equipment should likewise be
immune from the effects of electromagnetic disturbances and not impart disruptive signals on the
connections to the sensor.
The sensor is not intended for connection to a DC distribution network.
3.8.2 Cable Type
Due to the small size of the sensor it is unlikely to be directly affected by radiated RF energy. Any
RF energy that gets into the circuit will probably enter via the interconnecting cable.
To minimize the effect of nearby circuits and events, it is necessary to use screened cable
between the sensor and power supply / monitoring equipment. Failure to do so will invalidate the
EMC tests conducted by “Druck”.
The choice of cable type should reflect the environment through which it is going to run. Screened
cable should always be used where electrical noise is present. Good cabling practice will be
reflected in signal quality.
Table 4: EMC Standards
TERPS 8*00 Series
Models DPS 8***-T*-A*-C*-**-**[-…]
Models RPS 8***-T*-A*-C*-**-**[-…]
RPS8100 Minicore
Models RPS8100-***B[-…]
EN 61000-6-1:2007
EN 61000-6-2:2005
EN 61000-6-3:2007 + A1:2011
EN 61000-6-4:2007 + A1:2011
EN 61326-1:2013
EN 61326-2-3:2013
EN 61326-1:2013

Copyright 2010 Baker Hughes Company.
English–TERPS Instruction Manual | 9
3.8.3 Earthing
For the screening of the cable to be effective, it is essential that the screen or drain conductor is
permanently bonded to earth (ground). This should take place at the monitoring end of the cable
as close to the power supply as practical. Protection should be afforded to any unscreened
section of cable or circuit by means of a screened enclosure.
4. RPS Pressure Measurement
The RPS version of the TERPS sensor requires the user to measure a frequency and a voltage
to calculate pressure. The TERPS sensor has a very high level of repeatability that needs to be
matched by the measurement system.
Note: Best practice, when measuring a TERPS device, take both the frequency and voltage
measurements together. Where this is not possible, the measurements should be taken as
closely together as possible. Control the environment in which the TERPS is situated so it is not
subjected to sudden changes in temperature and pressure.
4.1 Measuring the Frequency
The frequency of the TERPS sensor element is output as a TTL square wave referenced to
ground in the range of 25 to 40 kHz. The frequency of the square wave needs to be measured to
a better than 6.5 digits (i.e. 30 kHz to better than 0.05 Hz) to allow the sensor to meet quoted
specification.
To make sure the calculated output is correct, the measurement device should be regularly
calibrated (refer to the manufacturer’s instructions) against a traceable standard.
4.2 Measuring the Diode Voltage
The diode signal is referenced to the ‘-VE TEMP’ electrical connection where available, otherwise
the diode signal is referenced to the ‘GROUND’ connection. It is a nominal 0.5 V at room
temperature, and changes with a nominal -2mV/°C. To achieve the quoted specification of the
sensor this signal must be measured to better than 0.01 mV.
To make sure the calculated output is correct, the measurement device should be regularly
calibrated (refer to the manufacturer’s instructions) against a traceable standard.
4.3 Calculating Pressure
During manufacture, a large number of pressures and temperatures are applied to the sensor to
build-up a mathematical description of its behavior. This data is then used to generate a
polynomial equation that relates the measured outputs from the sensor (bridge output and
temperature output) to the applied pressure.
The following example assumes a 5th order pressure (P5) and a 4th order temperature signal (T4).
If other orders of fit are used, these equations will need to be expanded to suit.
This equation is in the form:
where: P = Applied pressure in mbar
Ki, j = Calibration coefficient
x = Pressure signal in Hz
P Ki j
  x X– iy Y–  j
j0=
4

i0=
5

=

Copyright 2010 Baker Hughes Company.
10 | TERPS Instruction Manual–English
The coefficients Ki, j, X and Y are printed on the calibration certificate supplied with the pressure
sensor. A sample set is shown in Table 5:
4.4 Stored Coefficients
The coefficients are also stored internally on a serial EEPROM. See Appendix B for details on
data format and communication information.
The internal EEPROM is only available on some electrical connector variants of the RPS 8XXX
series, see data sheet or calibration certificate for electrical connection details.
5. DPS Pressure Measurement
The pressure reading and pressure units are outputted as ASCII text. The reading rate is user
programmable from ten readings per second to one reading per 9999 seconds.
5.1 Serial Data Communications Settings
Bi-directional digital communication, no handshaking, 9600 baud, 8 bit data, 1 stop bit. The
sensor may be used as a single transducer directly connected to a serial interface. It can also be
part of a network of devices using the programmed addressing facility.
5.2 Applications
The sensor may be used as a single transducer directly connected to a serial interface. It can also
be part of a network of devices using the programmed addressing facility.
X = Pressure normalizing factor
y = Temperature signal in mV
Y = Temperature normalizing factor
Table 5: Sample Coefficients
Sample Coefficients Sample Coefficients
Coefficient Value Coefficient Value
K00 9.173625E+02 K31 2.975355E-14
K01 -8.654275E-02 K32 -1.591914E-16
K02 3.705644E-05 K33 -3.095734E-18
K03 -3.071498E-08 K34 0.000000E+00
K04 0.000000E+00 K40 4.689744E-15
K10 3.792730E-01 K41 -1.867269E-18
K11 4.884866E-06 K42 -2.591512E-20
K12 -8.219704E-09 K43 6.066456E-23
K13 -3.283229E-11 K44 0.000000E+00
K14 0.000000E+00 K50 -2.043712E-20
K20 9.252440E-06 K51 -4.652603E-21
K21 4.893925E-11 K52 2.124089E-23
K22 2.872573E-14 K53 3.812421E-25
K23 -1.617304E-15 K54 0.000000E+00
K24 0.000000E+00 X 2.425645E+04
K30 1.185548E-10 Y 5.577031E+02

Copyright 2010 Baker Hughes Company.
English–TERPS Instruction Manual | 11
5.3 RS-485 Connections
Standalone RS-485 electrical connections:
i. RS-485 B (or RS-485 -)
ii. +ve supply
iii. 0V supply
iv. RS-485 A (or RS-485 +)
v. Transducer body (screen)
Note: For electrical connections refer to the sales data sheet.
Other connectors available, refer to manufacturer.
Figure 4: RS-485 Direct Connection
Figure 5: RS-485 Network Connection
5.4 RS-232 Connections
Standalone RS-232 electrical connections:
i. RS-232 Tx
ii. +ve supply
iii. 0V supply
iv. RS-232 Rx
Pressure
11 - 28 V DC
0 V
RS-485 A
RS-485 B
Pressure
Device 1
Address 1
Pressure
Device 2
Address 2
Pressure
Device 3
Address 3
+0V +0V +0V
RS-485
Terminator
RS-485
Terminator
RS-485
Interface
RS-485 +
RS-485 –

Copyright 2010 Baker Hughes Company.
12 | TERPS Instruction Manual–English
Note: For electrical connections refer to the sales data sheet.
Figure 6: RS-232 Direct Connection
5.5 USB Connection
Standalone USB electrical connection:
Figure 7: USB Connection
The maximum USB cable length is 3 metres (9 ft 10 in). The transducer can be connected to a
PC, or to a mobile device.
Drivers are available for the following operating systems:
• Android™
• Linux®
• Microsoft Windows®
5.6 Measuring Pressure
The frequency output from the sensor is counted for a fixed number of cycles by the
microprocessor. Measurement cycles are continuous, each cycle delivers new values of
frequency and temperature. See Section 6.4 on page 15 for instructions on how to read a
pressure measurement from the transducer.
5.7 Factory Defaults
Transducers are shipped with the following factory defaults (unless alternatives have been
requested):
Table 6: Factory Defaults
Parameter Value
Units mbar, displayed as text
after reading.
PINa000 (not set)
Address Direct mode
Long error messages Present
Communications Set-up 9600, 8, N, 1
Update rate 1 reading/second
Filter Disabled
User message None
Measurement speed 300 ms to 560 ms
Mode Direct
Pressure
11 - 28 V DC
0 V
RS-232 Tx
RS-232 Rx
Pressure
Micro-USB socket