Welch Allyn Duet CO2 Module User Manual
2
OEM Implementation Manual
Duet CO2Module OEM Implementation Manual
Copyright © 2001 by Welch Allyn OEM Technologies. Welch Allynâ and Protocolâ are
registered trademarks, and Pryonä is a trademark of Welch Allyn, Inc. Welch Allyn, Inc. is
protected under various patents and patents pending. Welch Allyn OEM Technologies is a
division of Welch Allyn, Inc.
Disclaimers: Welch Allyn OEM Technologies cautions the reader of this manual:
• This manual may be wholly or partially subject to change without notice.
• All rights are reserved. No one is permitted to reproduce or duplicate, in any form, the whole
or part of this manual without permission from W elch Allyn OEM Technologies.
For information concerning this document, contact:
Welch Allyn OEM Technologies
8500 SW Creekside Place
Beaverton, OR 97008-7107 U.S.A.
(503) 526-4900
Fax: (503) 526-4901
PN 120.00052 Rev. 1, 10/01
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Duet CO2Module OEM Implementation Manual
Table of Contents
Functional Description ..................................................................................................................................7
Introduction...............................................................................................................................................7
Intended Use .............................................................................................................................................. 7
Terminology...............................................................................................................................................8
Mainstream vs. Sidestream ...................................................................................................................... 8
Measuring Principle.................................................................................................................................. 8
Measurement Calculation......................................................................................................................10
Breath Algorithm .................................................................................................................................. 10
Measurement Compensation.................................................................................................................10
Water Vapor.......................................................................................................................................... 10
Pressure Broadening .............................................................................................................................10
Gas Mixing............................................................................................................................................11
O
O/desflurane.................................................................................................................................11
2/N2
BTPS..................................................................................................................................................... 11
Hardware Components ................................................................................................................................13
Introduction.............................................................................................................................................13
CO
Main Processor Board.................................................................................................................... 13
2
68HC11 Microprocessor ....................................................................................................................... 14
Reset Circuit..........................................................................................................................................14
Primary Power Supplies........................................................................................................................14
A/D Converter....................................................................................................................................... 14
D/A Converter....................................................................................................................................... 14
Source Hybrid ....................................................................................................................................... 14
Pressure transducers..............................................................................................................................15
Mainstream Components .......................................................................................................................15
Mainstream Daughter Board................................................................................................................. 15
Flex Circuit with Nicolay Receptacle ...................................................................................................15
Mainstream Sensor................................................................................................................................ 16
Airway Adapter..................................................................................................................................... 16
Sidestream Components ......................................................................................................................... 17
Sidestream Daughter Board .................................................................................................................. 17
Pump ..................................................................................................................................................... 17
Water trap Assembly............................................................................................................................. 17
Inlet and Exhaust Tubing ......................................................................................................................18
CO
Sample Line and Cannula..............................................................................................................18
2
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Duet CO2Module OEM Implementation Manual
Duet Configuration Drawings................................................................................................................ 19
Duet CO
Module Interface ......................................................................................................................... 21
2
Power Requirements............................................................................................................................... 21
CO
Main Processor Board.................................................................................................................... 21
2
Duet Module Interface Connector......................................................................................................... 22
Water Trap Receiver Assembly............................................................................................................. 22
Water Trap Switch Connection .............................................................................................................22
Pump ........................................................................................................................................................22
Mainstream Interface ............................................................................................................................. 23
Nicolay Receptacle ...............................................................................................................................23
Mainstream Sensor................................................................................................................................ 24
Sidestream Interface ...............................................................................................................................25
Pump ..................................................................................................................................................... 25
Water trap Receiver ..............................................................................................................................25
Water Trap Receiver Switch .................................................................................................................25
Exhaust Tubing .....................................................................................................................................25
Host/Module Communications .................................................................................................................... 27
Introduction.............................................................................................................................................27
Communication Interface....................................................................................................................... 27
System EEPROM.................................................................................................................................. 27
Packet Communication ......................................................................................................................... 28
Host Commands....................................................................................................................................28
Mode Commands .................................................................................................................................. 29
Simple Commands ................................................................................................................................29
Configuration Commands ..................................................................................................................... 31
Module Responses ................................................................................................................................ 34
Status Responses................................................................................................................................... 34
Status Response Mode Byte.................................................................................................................. 34
Status Response Message Byte ............................................................................................................. 35
Mode Command Responses.................................................................................................................. 36
Simple Command Response .................................................................................................................36
Configuration Command Responses..................................................................................................... 38
Additional Configuration Responses ....................................................................................................39
Software Protocol....................................................................................................................................40
Packets ..................................................................................................................................................40
Sensors .................................................................................................................................................. 40
Faults..................................................................................................................................................... 40
Module Resets....................................................................................................................................... 41
Module Time-outs................................................................................................................................. 41
SYSTEM BEHAVIORS - Dynamic Communications ......................................................................... 41
Status Message Code Table.................................................................................................................... 43
Host Command/Module Response Overview Table............................................................................. 44
Mainstream/Sidestream Hardware Status Table ................................................................................... 45
Mainstream Hardware Status Table ......................................................................................................45
Sidestream Hardware Status .................................................................................................................45
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Duet CO2Module OEM Implementation Manual
Pneumatic Operation ................................................................................................................................... 47
Introduction.............................................................................................................................................47
Normal Flow ............................................................................................................................................ 47
Pneumatic Events.................................................................................................................................... 47
Total Inlet Occlusion............................................................................................................................. 48
Partial Inlet Occlusion........................................................................................................................... 48
Total Exhaust Occlusion .......................................................................................................................48
Partial Exhaust Occlusion .....................................................................................................................48
Barometric Out Of Range ..................................................................................................................... 49
Unexpected Reverse Flow.....................................................................................................................49
Unexpected Forward Flow.................................................................................................................... 49
Internal Disconnects ...............................................................................................................................49
Water trap Receptacle ...........................................................................................................................49
Sample Chamber................................................................................................................................... 49
Flow Control Circuitry..........................................................................................................................49
Pump Inlet.............................................................................................................................................49
Pump Exhaust .......................................................................................................................................50
Pump Failure........................................................................................................................................... 50
Low Flow .............................................................................................................................................. 50
High Flow .............................................................................................................................................50
No Flow ................................................................................................................................................50
Regulatory ....................................................................................................................................................51
Overview ..................................................................................................................................................51
Welch Allyn OEM Technologies and Compliance with IEC 601-1 ..................................................... 51
OEM Responsibilities ........................................................................................................................... 51
Requirements........................................................................................................................................... 52
Electromagnetic Interference ................................................................................................................ 52
Electromagnetic Susceptibility..............................................................................................................52
Compliance Testing Summary.............................................................................................................. 52
ISO 9918 and EN 864 ........................................................................................................................... 52
Performance Validation............................................................................................................................... 53
Introduction.............................................................................................................................................53
Verification Procedures.......................................................................................................................... 53
Mainstream CO
Sidestream CO
Sensor Verification.................................................................................................... 53
2
Verification.................................................................................................................55
2
Pneumatic System Verification (Sidestream)........................................................................................56
Specifications ...............................................................................................................................................57
Duet CO
Module Specifications............................................................................................................57
2
Welch Allyn Mainstream Sensor II Specifications............................................................................... 61
Adult/Pediatric Single-Use Airway Adapter Specifications ................................................................62
Low Dead Space Single-Use Airway Adapter Specifications ..............................................................63
Adult/Pediatric Multi-Use Airway Adapter Specifications ................................................................. 64
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Duet CO2Module OEM Implementation Manual
Software Procedures ....................................................................................................................................65
CRC Code Calculation ...........................................................................................................................65
CRC Example: ......................................................................................................................................66
O
O/Desflurane Compensation......................................................................................................... 67
2/N2
Percent CO
Calculation........................................................................................................................ 68
2
Software Upgrade ...................................................................................................................................68
Download to FLASH Memory..............................................................................................................68
Command Line Parameters................................................................................................................... 68
Operation...............................................................................................................................................70
Motorola S Record Format....................................................................................................................71
EEPROM Maps............................................................................................................................................73
System EEPROM Map Table ...............................................................................................................73
Mainstream Sensor EEPROM Map Table ............................................................................................ 74
Error Messages & Recovery ........................................................................................................................75
Advisories ............................................................................................................................................. 75
Pneumatic System................................................................................................................................. 77
Soft Faults .............................................................................................................................................78
Sensor Faults......................................................................................................................................... 79
System Faults ........................................................................................................................................ 82
Part Numbers ...............................................................................................................................................85
Welch Allyn OEM Technologies Part Numbers...................................................................................85
Inclusions .............................................................................................................................................. 86
Glossary ........................................................................................................................................................ 87
CO2 Developer’s Kit..................................................................................................................................... 93
Introduction.............................................................................................................................................93
Disclaimer ............................................................................................................................................. 93
Software Installation............................................................................................................................... 93
Initial Setup .............................................................................................................................................94
Overview ..................................................................................................................................................95
Main Screen Illustration........................................................................................................................95
Menu Options Description ....................................................................................................................96
CO2 Evaluation Platform...................................................................................................................... 99
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Duet CO2Module OEM Implementation Manual
Functional Description
Introduction
The Duet CO2Module is designed to acquire data from either an external Welch Allyn OEM
Technologies mainstream CO
includes a sidestream CO
sensor or an internal sidestream system. The sidestream system
2
bench, electronics and pneumatic components.
2
The Duet CO
CO
waveform to the host system via a serial communications interface.
2
Module calculates CO2measurements and respiratory rate and outputs this data with
2
Intended Use
The Duet module is intended for use as a subsystem within a medical instrument or device. The
Module measures levels of carbon dioxide continuously or intermittently in the mainstream or
sidestream mode. The mainstream sensor, in conjunction with the module integrated into the host
system, allows for monitoring of intubated patients. The sidestream mode allows for monitoring of both
intubated and non-intubated patients. The module and its accessories should always be used as
described in the host system operator’s manual and only for the purpose(s) intended. The areas of
intended use include:
• Hospital Intensive Care Units (ICU)
• Hospital Emergency Department/EMS (ED/EMS)
• Surgical Operating Rooms (Anesthesia)
• Hospital Post Anesthesia Care Units (PACU)
• Outpatient Surgical Units
• Skilled Nursing Facilities / Sub-acute Care
• Transport (Air, Ground and Sea)
• Home Care / Traditional Health Care
The most common user will be the skilled professional nurse in the PACU, ICU, or step-down unit. In
addition, knowledgeable users in EMT and other higher care areas will make use of end tidal CO
.
2
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Duet CO2Module OEM Implementation Manual
Terminology
Capnography is the noninvasive measurement and graphic display of airway CO2concentration as a
function of time. The resulting waveform is called a capnogram. The evaluation of the capnogram is
useful in the assessment of the adequacy of carbon dioxide exchange in the lungs, integrity of the
patient’s airway, cardiopulmonary function and ventilator function.
Monitoring of CO
concentration at the end of expiration (point D) is referred to as End-Tidal CO
2
2
(ETCO2) monitoring.
76
CO
2
40
CD
(mmHg)
0
AB
E
Time
Mainstream vs. Sidestream
The patient’s expired gas may be sampled either directly off the airway external to the Duet Module or
aspirated from the patient through a cannula into the Module. The method used is dependent on the
patient’s airway status.
Mainstream capnography is used on intubated or tracheostomy patients. Intubation is the process of
inserting a tube into the patient’s trachea to deliver gases to the lungs. The sample chamber and CO
sensor are in line between the patient’s airway and the ventilator circuit. The signal is acquired external
to the Duet CO
Module while the module executes measurement calculation.
2
2
Sidestream capnography is used on patients who are intubated or non-intubated. The patient’sexpired
gas is aspirated from the airway and transported to the Duet Module through a sample line. The
sidestream sample chamber and sensor are embedded within the Duet CO
Module. The Duet CO
2
2
Module performs signal acquisition and measurement calculation.
The Duet CO
and sidestream input, hence the name Du
Module is designed to accommodate both Welch Allyn OEM Technologies mainstream
2
al End-Tidal (Duet) CO2Module.
Measuring Principle
CO2measurement is based on the infrared (IR) absorption characteristic of CO2molecules. The CO
sensor uses non-dispersive IR spectroscopy to measure the number of CO2molecules present in the
sample gas. CO
mass. CO
2
gas has a unique absorption band that is related to CO2molecule’s composition and
2
gas concentration is measured by detecting absorption in this band. The same
measurement technique is used for both mainstream and sidestream applications. Due to the nature of
the measurement technique employed, user calibration is not necessary with this system.
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Duet CO2Module OEM Implementation Manual
The basic components of the CO
sensor include
2
§ IR source § chopper wheel
§ IR detector § thermistor
§ optical filter § non-volatile memory
§ heater (mainstream only)
The IR source emits energy that is directed toward an IR detector. The detector generates a voltage
based on the amount of energy it receives. In the IR path between the IR source and the detector are
three components: an optical filter, which allows only a specific IR wavelength to pass, a gas sample
in the airway adapter and a chopper wheel. The chopper wheel has three distinct areas: a reference
gas cell, an open area and a dark, or closed area.
The chopper wheel rotates at 33 revolutions per second. As the single IR beam encounters the three
areas of the rotating chopper wheel, a signal is generated to create a ratio.
REFERENCE +
SAMPLE
DARK
SAMPLE
PHOTODETECTOR VOLTAGE
TIME
This ratio of “reference + patient sample/patient sample” is used to determine the CO2concentration in
the patient’s respiratory gas. This reduces error due to the variability in system components and
minimizes the effects of patient obstructions and secretions on the measurement. The dark area of the
chopper wheel provides a zero reference for re-calibrating the detector with each rotation. This results
in a self-calibrating system.
Since mainstream applications typically involve humidified circuits which can result in fog or
condensation on the airway adapter windows, it is necessary to use a heater to elevate the window
temperature above that of the exhaled respiratory gas. By doing so, the heater keeps the airway
adapter windows clear of condensation while also maintaining a stable detector temperature.
NOTE The optimal operating temperature for the mainstream sensor is 42
The thermistor provides temperature feedback to the heater control circuitry.
The non-volatile memory is an EEPROM containing calibration and manufacturing data specific to the
CO
sensor.
2
Welch Allyn OEM Technologies Confidential Page 9
o
C.
Duet CO2Module OEM Implementation Manual
Measurement Calculation
Measurements provided to the host system include ETCO2, Inspiratory CO2(InsCO2), or baseline CO2,
and respiratory rate (RR). These three measurements are collectively referred to as breath data. A
proprietary breath algorithm is used to calculate the breath data.
Breath Algorithm
Duet’s breath algorithm incorporates an initial learning period which, based on certain assumptions of
waveform morphology, establishes CO2reference points for threshold determinations. A sliding
CO
2
window is used to detect a stable maximum, or ETCO
value, and a baseline, or InsCO2value.
2
Thresholds are updated in real time with each breath. A signal averaging technique is used to calculate
the RR based on this set of measurements. By incorporating these adaptive and signal averaging
techniques, the breath algorithm effectively reports accurate CO
measurements while maintaining a
2
high level of noise immunity.
Measurement Compensation
IR absorption in the CO2wavelength band can be affected by a number of factors that alter the CO
measurement. The Duet Module automatically compensates for some of these factors while others
may be disabled by the host system.
These factors include
2
• water vapor
• pressure broadening
• gas mixing
• oxygen, nitrous oxide and desflurane or O
• B
ody Temperature, ambient Pressure and Saturated with water vapor or BTPS
O/desflurane
2/N2
Water Vapor
Water vapor compensation accounts for the effect that water vapor has IR absorption characteristics of
CO
molecules. During normal mainstream or sidestream operation, CO2measurements are adjusted
2
mathematically to compensate for this effect.
The host may choose to disable this compensation when performing a dry gas measurement in which
the gas does not contain water vapor. Dry gas procedures may include steady state measurements
and verification procedures. Steady state measurements are performed only when background CO
CO
present in the immediate environment, is measured. An example of a steady state measurement
2
is measuring the CO
content inside an incubator. Verification procedures use calibrated gas that is
2
,or
2
free of water vapor, or dry, as well.
The water vapor compensation is ON by default and may be enabled or disabled via a host system
command.
Pressure Broadening
Pressure broadening compensation accounts for the effects the barometric pressure has on CO
molecule distribution and is used in both mainstream and sidestream mode operation.
2
The pressure broadening compensation is ON by default and cannot be disabled by the host system.
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Gas Mixing
A small amount of gas “mixing” occurs as the CO2sample travels through the tubing to the sample
chamber. Gas mixing compensation accounts for the effect of low level gas mixing on the baseline
during inspiration in sidestream mode operation.
The gas mixing, or baseline, compensation is ON by default and cannot be disabled by the host
system.
O2/N2O/desflurane
O2/N2O/desflurane compensations account for effect of these gases on the IR absorption
characteristics of CO
recommendation for enabling these compensations.
molecules. Refer to page 67 for a description of this effect and a
2
The O
O/desflurane compensation is OFF by default and may be enabled or disabled via a host
2/N2
system command.
BTPS
Often the clinician’s intent is to determine the CO2levels within the patient’s lungs where gas exchange
is taking place. BTPS compensation corrects for the environmental differences between the
measurement site (i.e. the bench) and “deep lung” CO
The BTPS compensation is ON by default and may be enabled or disabled via a host system
command.
.
2
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Duet CO2Module OEM Implementation Manual
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Hardware Components
Introduction
The OEM defines the resident Duet CO2Module hardware necessary for mainstream and/or
sidestream operation. Configurations may include mainstream and sidestream sampling (MS/SS Duet
CO
Module), mainstream sampling only (MS Duet CO2Module) or sidestream sampling only (SS Duet
2
Module). Refer to 19 for drawings of these configurations.
CO
2
An additional consideration is the inclusion of an isolated power supply. Mainstream operation requires
an isolated power supply to meet patient safety requirements.
NOTE The OEM must supply Patient isolation when using mainstream Duet and the mainstream
sensor.
The motherboard for all Duet CO
Module configurations is referred to as the CO2main processor
2
board. Mainstream and sidestream sampling requires the addition of the mainstream and/or sidestream
daughter boards with associated hardware to function.
CO2 Main Processor Board
The CO2main processor board provides the interface to the mainstream and sidestream daughter
boards and the host system; manages power requirements; calculates measurements; and regulates
heater output and pump flow.
The functional components of the CO
§ 68HC11 microprocessor with external memory
§ reset circuit
§ primary power supplies
§ analog to digital (A/D) converter
§ digital to analog (D/A) converter
§ source hybrid
main processor board include
2
§ barometric pressure transducers
Welch Allyn OEM Technologies Confidential Page 13
Duet CO2Module OEM Implementation Manual
68HC11 Microprocessor
The microprocessor controls feedback to the temperature and pressure transducers, heater output in
mainstream applications and pump flow in sidestream applications. The microprocessor also provides
the communication interface to the host system and the interfaces to the external A/D and D/A
converters and sensor EEPROM memory. An internal multiplexed A/D converter is used for digital
conversion and for monitoring some of the power supplies for fault determinations.
All address decoding is done by the microprocessor. The software code is stored in FLASH memory
and is supplemented by an external static RAM chip. The boot mode of the microprocessor is used to
install new software into the FLASH device.
Reset Circuit
The first section of a 556 timer is connected to a serial receive data line such that the microprocessor is
forced into reset if the data line is held in a break condition for greater than 10 msec. A second timer
section is used to ascertain if the break condition is maintained for more than 500 msec.
Holding the receive data line in a break condition for a period of time greater than 10 msec and less
than 500 msec is referred to as a reset.
A hard reset occurs when the break condition is held longer than 500msec. This condition forces the
microprocessor to enter the boot mode after the break is released.
A reset controller performs power ON, reset and low voltage lockouts. Under voltage lockout is set to
approximately 4.5 V. On power up, the microprocessor is held in reset for about 100 msec after the
supply rises above 4.5 V.
Primary Power Supplies
All primary power supplies run off a single voltage power source and are converted on the main board
to various levels. With the Duet CO
power supplied by the host system.
V
IN
Module, the power source is derived from the +8.00 - +12.00 VDC
2
The +8.00 VDC minimum requirement may be reduced if longer mainstream sensor warm up times are
acceptable or if only sidestream operation is intended.
A/D Converter
The 8 channel 12 bit serial A/D converter converts the following analog signals into a binary data
stream for the microprocessor: analog waveform from the optical bench, temperature of the optical
bench, barometric pressure, pneumatic flow rate (sidestream).
D/A Converter
The 12 bit serial interface D/A converter provides bench motor speed control, source current selection
and detector bias circuit control.
Source Hybrid
The optical benches require that the IR sources be current regulated. The current sensing circuitry is
located on a ceramic hybrid module, or source hybrid. A regulator is used that adjusts its output voltage
to maintain a constant current. The output of the regulator is then fed to a switch that can route the
output to either the mainstream or sidestream board.
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Pressure transducers
The barometric pressure circuitry monitors pressure via transducers in order to compensate for the
effect of pressure variation on CO
measurements. The transducers include:
2
§ an absolute pressure transducer which monitors the ambient pressure for pressure broadening
effects on the CO
signal.
2
§ a second absolute pressure transducer that monitors internal bench pressures.
§ a differential pressure transducer that is used for pump flow regulation.
Mainstream Components
The functional components necessary for mainstream operation include
§ mainstream daughter board
§ flex circuit with Nicolay receptacle
§ mainstream sensor
§ airway adapter
Mainstream Daughter Board
The mainstream daughter board, or mainstream stick, provides controls to start and maintain the
chopper motor speed; controls to regulate heater output and monitor sensor temperature; and logic for
mainstream fault sensing.
The functional components of the mainstream daughter board include the motor control hybrid, the
heater control circuitry and the flex circuit connector.
The motor control hybrid operates via drive coils in the chopper motor to provide feedback to the
microprocessor to drive the motor. The microprocessor uses this signal to synchronize the waveform
signal with the chopper motor and to start and maintain the motor speed.
The heater control circuitry controls the heater output and monitors internal bench temperature. A
signal from the microprocessor is applied to the heater element in the sensor head. A thermistor
located in the sensor housing provides temperature feedback to the heater control. This feedback is
used to control the sensor housing temperature.
The heater power supply uses a pulse width modulated, or PWM, signal to step down the raw input
voltage to a level appropriate for maintaining the mainstream sensor at 42
o
C.
The flex circuit connector on the mainstream daughter board provides electrical connection of the flex
circuit to the mainstream daughter board.
Flex Circuit with Nicolay Receptacle
The flex circuit with Nicolay receptacle interfaces the mainstream sensor to the mainstream daughter
board.
The functional components of the flex circuit with Nicolay receptacle include the Welch Allyn OEM
Technologies flex circuit, or flex circuit, and the Nicolay receptacle.
Welch Allyn OEM Technologies Confidential Page 15
Duet CO2Module OEM Implementation Manual
NOTE Flex circuit and Nicolay receptacle are not included with the MS/SS and MS Duet CO
2
Modules and may be ordered separately from Welch Allyn OEM Technologies or supplied
directly by the OEM.
NOTE Flex circuit layout and dielectric strength may be customized as per OEM requirements. The
OEM must supply routing and layout drawings to Welch Allyn OEM Technologies for a
custom flex design. Consult with Welch Allyn OEM Technologies for additional information
on ordering a custom flex circuit.
The Welch Allyn OEM Technologies flex circuit is double-insulated to provide single fault protection
and provides up to 10kV dielectric strength.
The Nicolay receptacle is fastened to the housing of the host system and provides the interface for the
mainstream sensor.
Mainstream Sensor
The mainstream sensor houses the hardware necessary to determine the CO2molecule count in the
sample chamber. The IR beam passes from the IR source on one side of the sensor housing through
the windows of the airway adapter to the other side of the housing. This output is communicated to the
Duet CO
The functional components of the mainstream sensor include the mainstream sensor connector, cable
and mainstream sensor head.
NOTE Mainstream sensor is not included with the MS/SS and MS Duet CO
Module for measurement calculation.
2
ordered separately from Welch Allyn OEM Technologies.
Modules and must be
2
The mainstream sensor connector interfaces the mainstream sensor to the Nicolay receptacle.
Within the mainstream sensor connector is an EEPROM that retains calibration information for the
sensor and OEM specific information that allows the sensor to be used only with the electronics
identified for a specific OEM.
NOTE Mainstream sensor EEPROM is pre-configured by Welch Allyn OEM Technologies after
obtaining OEM specific information.
The cable connects the mainstream sensor connector to the mainstream sensor head.
The mainstream sensor head houses the IR optical components, chopper drive motor and
mainstream sensor circuit board. The inverted U-shaped housing of the mainstream sensor head
snaps onto the airway adapter.
Airway Adapter
The airway adapter is used as the sample chamber for the sensor and is connected between the
endotrachial tube and the ventilator’s wye piece. A variety of airway adapters are available. Selection is
typically based on adult/pediatric/neonate status, multiple use versus disposable and low dead space
performance.
NOTE Airway adapter is not included with the MS/SS and MS Duet CO
ordered separately from Welch Allyn OEM Technologies.
Modules and may be
2
Page 16 Confidential Welch Allyn OEM Technologies
Duet CO2Module OEM Implementation Manual
Sidestream Components
The functional components necessary for sidestream operation include
§ sidestream daughter board
§ pump
§ Water trap assembly and receiver
§ inlet and exhaust tubing
§ CO
sample line/cannula
2
Sidestream Daughter Board
The sidestream daughter board provides the interface to the sidestream CO2sensor; pump and Water
trap receiver switch; controls to start and maintain the chopper motor speed; and provides feedback to
regulate the pump flow.
The functional components of the sidestream daughter board include the sidestream bench, the motor
control hybrid (refer to Mainstream Components section), the flow control circuitry and the pump and
Water trap assembly connectors.
Apart from the absence of a heater, the sidestream bench operates in the same manner as the
mainstream sensor. Additionally, the microprocessor monitors the internal sensor temperature through
thermistor feedback to compensate for temperature variation.
The flow control circuitry regulates flow using a fixed orifice flow sensor that provides feedback to a
circuit controlling power to the pump. A differential pressure transducer measures the pressure drop
across a restrictor. It is used as feedback to adjust the pump speed. The pump power supply steps
down the raw voltage applied to the board to a level appropriate for maintaining the desired pump flow
rate.
The pump connector provides electrical connection of the pump to the sidestream daughter board.
The Water trap assembly connector provides electrical connection of the Water trap switch to the
sidestream daughter board.
Pump
The electrically driven miniature oil-free diaphragm pump draws the sample through the sample line to
the sample chamber by creating a vacuum. Fault states such as exhaust and Water trap occlusions are
recognized by the flow control circuitry.
Water trap Assembly
The Water trap assembly provides the principal filter medium for the airway gas sample before the gas
is delivered to the sample chamber.
The functional components of the Water trap assembly include the Water trap, the W ater trap receiver
and the Water trap receiver switch.
NOTE Water trap, Water trap receiver and Water trap receiver switch are not included with the
MS/SS and SS Duet CO
Technologies or supplied by the OEM.
Welch Allyn OEM Technologies Confidential Page 17
Modules and may be ordered separately from Welch Allyn OEM
2
Duet CO2Module OEM Implementation Manual
The Water trap is a user-supplied cartridge that removes excess moisture in the sample line before the
sample is delivered to the sample chamber. The Water trap is designed to fully occlude once the filter is
saturated.
The Water trap receiver is the receptacle for the Water trap and can be molded by the OEM into the
main housing of the host monitor. The external end of the Water trap is connected to the sample line.
The Water trap receiver switch assembly ensures that the W ater trap is properly inserted into the
Water trap receiver before the pump begins operation. This eliminates the possibility of the user
bypassing the Water trap.
Inlet and Exhaust Tubing
The internal inlet tubing provides the means to transport the airway gas sample from the Water trap
receiver to the sidestream bench. The inlet tubing includes the tubing, connectors and a secondary
shutoff pellet. Attachment of the inlet tubing to the Water trap receiver is via a Luerâ connector. A
secondary shutoff pellet is attached in line with the inlet tubing to provide additional insurance for
saturation detection.
The exhaust tubing provide the means to expel the exhaust gas. A filter, or 5um screen, is in line with
the exhaust tubing to muffle, or reduce the pump noise.
CO2 Sample Line and Cannula
ACO2sample line, or sample line, is used to transport the airway gas sample from patient to the Water
trap assembly. Connection of the sample line on the patient side is via a female oriented Luerâ
connector attached to the sample line.
Note: Sample lines are not included with the Duet CO
Module and may be ordered separately from
2
Welch Allyn OEM Technologies or other suppliers.
For non-intubated patients, the sample line connects to a cannula that is positioned on the patient. A
variety of cannulas are available to accommodate patient requirements. Nasal, oral/nasal and divided
cannulas that deliver oxygen and sample CO
Note Cannulas are not included with the Duet CO
simultaneously may be used.
2
Module and may be ordered separately from
2
Welch Allyn OEM Technologies or other suppliers.
For an intubated patient, the sidestream sample line connects to the patient’s breathing circuit.
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Duet CO2Module OEM Implementation Manual
Duet Configuration Drawings
Sidestream
Stick
Host System
Serial Port
Interface
Power
Secondary
Shut Off
Watertrap
Receptacle
Watertrap
Mainstream
Stick
Nicolay
Receptacle
Mainstream
Sensor
Main PWB
Airway Adapter
(Adult, Neonatal or Reusable)
Nasal
Cannula
Sidestream and Mainstream
Measurement System
Welch Allyn OEM Technologies Confidential Page 19
Host System
Serial Port
Interface
Power
Sidestream
Stick
Duet CO2Module OEM Implementation Manual
Secondary
Shut Off
Watertrap
Receptacle
Watertrap
Host System
Mainstream
Stick
Main PWB
Sidestream
Measurement System
Serial Port
Interface
Powe r
Nasal
Cannula
Main PWB
Nicolay
Receptacle
Mainstream
Measurement System
Mainstream
Sensor
Airway Adapter
(Adult, Neonatal or Reusable)
Page 20 Confidential Welch Allyn OEM Technologies
Duet CO2Module OEM Implementation Manual
(
)
Duet CO2 Module Interface
Power Requirements
Description Typical
Input voltagerange +8.00 to +12.00 VDC, 150 mV peak to peak ripple
Non-measurement power 570 mW at +8.00 VDC
Mainstream warm up power 5 W at +8.00 VDC
Mainstream operating power 2.8 W at 25° C, average
Sidestream operating power 1.3 W at +8.00 VDC
Sidestream occluded power 1.8 W at +8.00 VDC
Sidestream pump stalled power 3.0 W at +8.0 VDC
a. Optimal input voltage is +8.00 VDC. Typical power consumption increases slightly with higher input
voltages.
a
The host must supply fused input voltage to the Duet CO
the power input side of the Duet CO
voltage) and 1.50 A (8.00 V input voltage).
Module are 1.00 A (12.00 V input voltage), 1.25 A (10.00 V input
2
CO2 Main Processor Board
Description Specification
Dimensions
(MS & SS included)
Clearance 1.00 in (25.40 mm) above board
Orientation No limitations
Weight < 1 lb (454 gm)
3.15 in L × 3.90 in W × 1.22 in H
80 mm L×100 mm W×31 mm H
0.20 in (5.00 mm) below board
Module. The actual slo blo fuse values for
2
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Duet CO2Module OEM Implementation Manual
Duet Module Interface Connector
The module interface connector is a 4 pin connector (Molex p/n 22-11-2042). The host may usea4pin
polarized housing (Molex p/n 22-01-3047 with Molex 2759 series terminals) or equivalent.
Pin Signal Signal Description
1V
2 GND ground
3 TxD data from CO2main processor board to host system
4 RxD data from host system to CO2main processor board
a. The “square” plated through-hole designates pin 1 on the CO2main processor board.
input power
Water Trap Receiver Assembly
The internal space available in the host monitor should be considered when incorporating the Water
trap receiver into the host system design. To accommodate various OEM dimensions, two water trap
receivers are offered: long and short. The long Water trap receiver requires more intrusion into the host
monitor but the Water trap does not protrude as far externally from the host chassis than with the short
Water trap receiver. The Water trap receiver assembly includes a mounted micro-switch to detect the
insertion of a Water trap.
Water Trap Switch Connection
The Water trap receiver switch is wired in the “normally open” configuration.
The Water trap switch connection is available via the connector on the sidestream daughter board. The
switch assembly is equipped with a 2-pin connector (Molex P/N 22-01-3027) which electrically
connects directly to the sidestream daughter board at P502.
Pump
The pump is mounted on the Main Processor Board. The pump wiring harness is connected to the
sidestream daughter board via a 2-pin connector (Molex P/N 22-01-3027).
Page 22 Confidential Welch Allyn OEM Technologies
Duet CO2Module OEM Implementation Manual
Mainstream Interface
Nicolay Receptacle
Pin Signal
1 sense ground
2 - bias
3 ground return
4 thermistor
5drivecoil
6 + bias
7 ground return
8 IR detector output
9+5V
10 IR source
11 ground return
12 heater
13 signal ground
14 -5 V
15 EEPROM clock
16 sense coil
17 EEPROM data
18 EEPROM CS
19 N/C
20 ground return
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Duet CO2Module OEM Implementation Manual
g
a
Mainstream Sensor
Description Specification
Dimensions
Weight < 1.25 oz (18.5 gm) without cable
Cable Length 10 ft / +1.0 in / -4.0 in
Volume approximately 1.0 in3(16.59 cm3)
The mainstream sensor warm up has three phases: preliminary warm up, sensor start up and final
warm up. The preliminary warm up phase is the primary warming period. Once the sensor reaches the
near final temperature of 42
conditions are met, the mainstream sensor returns to complete the warm up phase.
Phase/Task Elapsed Time (typical) Response Suggested Message
Preliminary/
Warm sensor
0.75 in L × 1.35 in W × 1.00 in H
(19.5 mm L × 34.29 mm W × 25.4 mm H)
(3.5 m / +2.5 cm / -10.2 cm)
o
C, the sensor progresses to the sensor start up phase. Once start-up
45 - 90 seconds <S0310> Sensor Warming
Sensor start up/
5 - 10 seconds <S0311> Sensor Warming
Start sensor motor
Final warm up/
10 seconds <S0311> Sensor Warming
Turn on IR source and
wait for si
nal
The warm up time of the mainstream sensor is dependent on the ambient temperature and the power
available to the heater circuit.
Note: If less power is supplied, the Duet CO
Module may be configured for a longer warm up time.
2
The following table lists typical approximate warm up times based on these variables in minutes.
Temperature 2.5 W
3.5 W 4.5 W 5.5 W
5oC 9:50 5:00 3:00 2:20
25oC 3:00 1:40 1:00 0:40
40oC 0:50 0:20 0:15 0:15
a. Power delivered to the sensor. For example, to supply 2.5 W to the sensor, the CO2main processor
board needs 3.5 W.
After operating temperature is reached, the bench motor is started and the signal acquisition begins to
servo the bench signal into the operating range. This may add 20 to 30 seconds to the warm up time.
Page 24 Confidential Welch Allyn OEM Technologies
Duet CO2Module OEM Implementation Manual
Sidestream Interface
Pump
The pump is mounted on the CO2main processor board and is electrically connected directly to the
sidestream daughter board. The pump wiring harness length is typically 4 inches and is connected to
the sidestream daughter board viaa2pinconnector (Molex p/n 22-01-3027).
Note: The pump wiring harness length may be modified to accommodate OEM design
requirements if, for example, the pump requires mounting off of the main processor board.
The pump wiring meets typical insulation standards but does not meet patient isolation
requirements. If the pump must be moved to a different location, such as a non-isolated section,
patient isolation requirements must not be compromised. Refer to Regulatory Section for
additional safety information.
Water trap Receiver
The internal space available in the host monitor must be considered when incorporating the Water trap
receiver into a design. To accommodate this requirement, two Water trap receivers are offered: the
long and short receiver. The short Water trap receiver offers less intrusion into the host monitor but
causes the Water trap to extend further externally.
Water Trap Receiver Switch
The Water trap receiver switch is wired in the “normally open” configuration.
The Water trap receiver switch connects directly to the sidestream daughter board via a wiring harness
and connector. The Water trap receiver switch assembly is equipped witha2pinconnector (Molex p/n
22-01-3027) which electrically connects directly to the sidestream daughter board. A wiring harness is
provided and may be altered to accommodate OEM design requirements.
Note: The Water trap receiver switch wiring meets typical insulation standards but does not meet
patient isolation requirements. W hen applicable, harness routing must not violate patient isolation
requirements. Refer to Regulatory Section for additional safety information.
Exhaust Tubing
In the event of an exhaust tubing malfunction, gas buildup can occur within the host system.
WARNING To protect against this occurring, exhaust tubing must be single fault protected.
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Duet CO2Module OEM Implementation Manual
Page 26 Confidential Welch Allyn OEM Technologies
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Host/Module Communications
Introduction
The Duet CO2Module is a command driven slave device capable of communicating with a host system
over an asynchronous serial communication line. After start up, the Duet CO
periodic CO
by the host system to the Duet CO
waveform and breath data packets to the host system. All other communication is initiated
2
Module.
2
Module communicates
2
The Duet CO
Module and the host system are referred to as the “module” and host” in this chapter.
2
Communication Interface
§ 9600 baud rate (user-selectable)
§ full duplex
§ Asynchronous using standard non return to zero (NRZ) format.
{1 start bit 7 or 8 data bits even parity 1 stop bit}
§ Receive data input (RxD) is the buffered input of a 74HC14. A pull-up is provided on the
module so it can be driven by an open collector source.
§ Transmit data output (TxD) is the collector of a 2N4401 transistor driven with a 10 K base
resistor from the output of a 74HC14. A weak pull-up is provided to source a CMOS load.
§ Non-isolated module power and communications are provided at P104.
System EEPROM
System EEPROM contains system configuration and operational constants that are encoded by Welch
Allyn OEM Technologies. While the majority of parameters pertain to Welch Allyn OEM Technologies
manufacturing and operational defaults, specific parameters may be customized to accommodate
OEM requirements.
System parameters that the OEM may specify a default value include
§ baud rate § module start up mode
§ data format § initial pump flow rate
The baud rate may be set to a maximum of 9600. (Defaults to 9600.)
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Duet CO2Module OEM Implementation Manual
The data format options are 7 or 8 bits. (Defaults to 7 bit.)
The module start up mode options are auto run, measurement, warm standby, standby and fault.
(Defaults to sidestream fault mode.)
The initial pump flow rate option allows the host to specify desired default flow rate. (Defaults to
175ml/min.)
Refer to the System EEPROM Map Table in Appendix A Software Procedures for further information.
Packet Communication
Transmission of host commands and module responses is via packets. The following byte structure
represents a packet.
Packet format:
< start of text (STX) 02h
X identifier 1*(ASCII)
n
xx
yy CCITT/CRC code 2*(ASCII)
> end of text (ETX) 03h
data n(hex char)
ASCII characters have values in the range of 00h to 7Fh. The identifier is case sensitive. Characters
between 00h and 20h are reserved as control characters.
Transmission of all packets starts with a “<” STX control character and ends with a CCITT/CRC code
and “>” ETX control character. Between STX and ETX is an identifier and n bytes of ASCII data. The
length of the packet is defined by the identifier character. Packet length cannot exceed 25 bytes with a
maximum of 20 bytes of data allowed. Packets without the STX control character are ignored. The
CRC code is computed on values between STX and CRC code.
02h X xxnyy 03h
Host Commands
The host communicates to the module via commands. These include
§ mode commands, to request a change in the operating mode.
§ simple commands, to request data or a status change. Data is not sent with these commands.
§ configuration commands, to specify custom system settings. Data is sent with these
commands.
Page 28 Confidential Welch Allyn OEM Technologies
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Mode Commands
Mode commands allow the host to put the module into one of the four operating modes.
Host Command Description
<M04> for MS
<M24> for SS
Enter auto run mode
To start automatic sampling and data packet transmission at default
intervals of real time CO
waveform and breath data. A mainstream
2
sensor disconnect or a sidestream water trap removal causes the
module to wait for a sensor reconnect or sidestream Water trap
insertion. This is the preferred operating mode since temporary
sensor removal and replacement is typical in normal operation.
<M03> for MS
Enter measurement mode
<M23> for SS
Same as auto run mode except for mainstream sensor disconnects
and sidestream Water trap removals. Instead of waiting for a sensor
reconnect or Water trap insertion, the sensor’s activity is halted and
the module reverts to the standby mode and requires a new <M03>
or <M23> host command to restart measurement.
<M02>
Enter warm standby mode
Provides a low power standby state for the module during sensor
warm up in mainstream operation since warm up time may be as long
as several minutes. Standby mode keeps the sensor warmed and
ready. Standby mode also reduces battery drain.
<M01> for MS
Enter standby mode
<M21> for SS
Used when a low power standby state for the module is desirable.
This prolongs the life expectancy of the IR source, chopper motor and
heater since these components are disabled in this mode.
The module automatically reverts to a fault mode if a module or sensor fault occurs. A message is sent
via the status response by the module to the host.
Simple Commands
Simple commands instruct the module to send module data or sensor EEPROM data and to reset the
module software or a sensor error.
Host Command Description
<C00>
Request module status
To confirm operating mode, fault status and module and sensor
operation.
<C20> Request software version
<C21> Request hardware version
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Duet CO2Module OEM Implementation Manual
Host Command Description
<C22> Request ambient barometric pressure
To calculate %CO
.
2
<C23> Request sensor temperature
<C24> Request chopper motor speed
<C26> Request single CO2measurement
<C24> Request single breath data packet
<C2E> Request current pump flow rate
<C31> Request sensor EEPROM revision #
<C32> Request sensor OEM specific code
<C33> Request sensor serial #
<C3A> Request last calibration date
<C80> Software reset
<C82> Clear sensor error
To retry or verify fault condition.
Page 30 Confidential Welch Allyn OEM Technologies
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