Datex-Ohmeda S-5 Service Manual M-PP

S/5

Datex-Ohmeda

TM

Dual Pressure Module, M-PP (Rev. 01)

Technical Reference Manual

Datex-Ohmeda Inc.
3030 Ohmeda Drive
53707-7550 MADISON, WIS
USA
Tel. [phone], Fax. [phone]

www.us.datex-ohmeda.com

All specifications are subject to change without notice.

Document No. 8001014-1

June 2001

Datex-Ohmeda Division,

Instrumentarium Corp.

P.O. Box 900, FIN-00031

DATEX-OHMEDA, FINLAND

Tel. [phone] Fax [phone]

www.datex-ohmeda.com

 Instrumentarium Corp. All rights reserved.

Table of contents

TABLE OF CONTENTS

Dual Pressure Module, M-PP

TABLE OF CONTENTS i

TABLE OF FIGURES ii

Introduction 1

1 Specifications 2

1.1 General specifications ..............................................................................................................................2

1.2 Typical performance .................................................................................................................................2

1.3 Technical specifications............................................................................................................................2

2 Functional Description 3

2.1 Measurement principle .............................................................................................................................3

2.2 Main components.....................................................................................................................................3

2.2.1 PP board..........................................................................................................................................4

2.3 Connectors and signals.............................................................................................................................7

2.3.1 Module bus connector......................................................................................................................7

2.3.2 Front panel connectors.....................................................................................................................8

2.3.3 Other connectors..............................................................................................................................8

3 Service Procedures 9

3.1 General service information.......................................................................................................................9

3.2 Service check .........................................................................................................................................10

3.2.1 Recommended tools ......................................................................................................................10

3.3 Disassembly and reassembly..................................................................................................................13

3.4 Adjustments and calibrations..................................................................................................................14

3.4.1 Invasive pressure calibration...........................................................................................................14

4 Troubleshooting 15

4.1 Troubleshooting chart .............................................................................................................................15

4.2 Troubleshooting flowchart .......................................................................................................................16

5Service Menu 17

5.1 PP menu................................................................................................................................................18

5.2 PP calibrations menu..............................................................................................................................19

6 Spare Parts 20

6.1 Spare parts list .......................................................................................................................................20

6.1.1 Dual Pressure Module, M-PP, Rev. 00 .............................................................................................20

6.1.2 Dual Pressure Module, M-PP, Rev. 01 .............................................................................................21

6.1.3 Front panel stickers for AS/3 modules (square buttons) ...................................................................21

6.1.4 Front panel stickers for S/5 modules (round buttons).......................................................................21

7 Earlier Revisions 23

APPENDIX A 25

Service check form A-1

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Datex-Ohmeda S/5 monitors

TABLE OF FIGURES

Figure 1 Dual Pressure Module, M-PP.................................................................................................................1

Figure 2 Dual Pressure Module, M-PP, front panel...............................................................................................3

Figure 3 PP board block diagram........................................................................................................................4

Figure 4 Pressure transducer principle of operation.............................................................................................5

Figure 5 Serial communication and opto isolation sections .................................................................................6

Figure 6 Module bus connector (X1) ...................................................................................................................7

Figure 7 M-PP troubleshooting flowchart ..........................................................................................................16

ii

Document No 8001014-1

INTRODUCTION

This section provides information for the maintenance and service of the Dual Pressure Module, M­PP. The M-PP module is a single width plug-in module designed for use with the S/5 monitors. The
Dual Pressure module provides invasive blood pressure (InvBP) measurement.

Dual Pressure Module, M-PP

Figure 1 Dual Pressure Module, M-PP

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Datex-Ohmeda S/5 monitors

1 SPECIFICATIONS

1.1 General specifications

Module size, W × D × H 37 × 180 × 112 mm / 1.5 × 7.1 × 4.4 in
Module weight 0.35 kg / 0.8 lbs
Power consumption approximately 3.5 W

1.2 Typical performance

Measurement range -40...+320 mmHg
Accuracy ±5 % or ±2 mmHg, whichever is greater
Zero adjustment range ±150 mmHg
Calibration range ±20 %
Scales Upper limit is adjustable between 10 and 300 mmHg in steps of

Sweep speed 12.5, 25, 50 mm/s

10. Lower limit is 10 % of selected upper limit below zero.

DIGITAL DISPLAY
Range -40...+320 mmHg
Resolution ±1 mmHg

WAVEFORM DISPLAY
Range -30...+300 mmHg

HEART RATE FROM ARTERIAL PRESSURE
Measurement range 30...250 bpm
Resolution 1 bpm
Accuracy ±5 bpm or ±5 %, whichever is greater

1.3 Technical specifications

Accuracy ±5 % or ±2 mmHg, whichever is greater
Transducer and input sensitivity 5 µV/V/mmHg, 5 VDC, 20 mA max current
Nonlinearity < 1 %, 0...200 mmHg

Filter 0...4 - 22 Hz adjustable
Zero set accuracy ±1 mmHg
Calibration resolution ±1 mmHg
Zero time < 15 sec

Protection against electrical shock Type CF defibrillation proof

< 2 %, -40...0 and 200...320 mmHg

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DIGITAL DISPLAY AVERAGING
Art and P1 digital displays are averaged over 5 seconds and updated at 5 second intervals. All
other pressures have respiration artifact rejection.

NOTE: The accuracy of the measurement may be different from that specified, depending on the
transducer/probe being used. Please check the transducer/probe specification.

2 FUNCTIONAL DESCRIPTION

2.1 Measurement principle

To measure invasive blood pressure, a catheter is inserted into an artery or vein. The invasive
pressure setup, consisting of connecting tubing, pressure transducer, an intravenous bag of normal
saline all connected together by stopcocks, is attached to the catheter. The transducer is placed at
the same level with the heart, and is electrically zeroed.

The transducer is a piezo-resistive device that converts the pressure signal to a voltage. The monitor
interprets the voltage signal so that pressure data and pressure waveforms can be displayed.

2.2 Main components

The main components of the Dual Pressure Module, M-PP, are a PP circuit board, a front panel and
a box. The front panel includes two Nicolay-type connectors, P5 and P6, and two direct function
keys, Zero P5 and Zero P6 for pressure zeroing.

Dual Pressure Module, M-PP

Communication between the Dual Pressure Module and the Central Unit is an RS485 serial
interface.

The power supply voltages to the Dual Pressure Module are generated in the power supply section
of the Central Unit. All electrical connections between the Dual Pressure Module and the Central
Unit are via a 25-pin D-connector at the back of the module.

Zero

P5

P5

Zero

P6

P6

Figure 2 Dual Pressure Module, M-PP, front panel

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Datex-Ohmeda S/5 monitors

2.2.1 PP board

RS485 Driver
for data

Module bus connector

Module data

Module reset

RS485 Driver
for module
reset

Power for
Communication

Power
reset

Power for
module

Power
non­isolation
section

Opto
isolation

Non volatile
memory

Reset

Module
bus
data

Patient isolation

µprocessor

RAM internal 2K

EPROM 48K

RS communication

AD-converter

-8 chn

-12bit

Press AD

INV
PRESS
measuring
unit

external 16K

Isolation
transformer

Power
isolation
section

Front panel
keys

Figure 3 PP board block diagram

Microprocessor unit

The microprocessor uses the Intel 80C196KC-16 CPU which includes three A/D converters and a
UART. The microprocessor uses external memories, an 8-bit data bus, a 16 MHz oscillator, an open
collector reset, and a watchdog timer. The three A/D-converters within the CPU convert the analog
input signals to digital. The internal UART communicates and transfers data between the module
and the CPU board in the monitor.High speed I/O is used to obtain the pulse control sequence
necessary for pulse oximetry measurement. It receives its timing clock signal from the 16 MHz
oscillator.

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Patient connectors

Invasive blood pressure measurement unit

An isolated +5 V supply is connected to the input of the pressure transducer bridge circuit. From
the bridge circuit output a differential voltage, which depends on blood pressure and input supply
voltage, is calculated using the following formula:

Uout = Uin × Pressure × 5 V

where Uin = 5 V

Uout = 25 V × Pressure [mmHg]

Pressure amplification is performed by the instrumentation amplifier. The gain of the amplifier is
set so that the level of the signal transferred to the A/D converter stays within the measurement
range even when there are circumstantial offsets or offsets caused by the pressure transducer. The
input filter before the amplifier attenuates high frequency disturbances.

Dual Pressure Module, M-PP

Figure 4 Pressure transducer principle of operation

Serial communication

Serial communication between the Dual Pressure Module and the Central Unit is via an RS485
type bus. The communication bus drivers are powered from the Central Unit Module Bus. The
module isolation section (+5 V) is powered from the isolated power supply.

The buffers of the serial communication drivers are controlled by a reset signal such that when the
reset is active the drivers do not transfer data.

Vin

Pressure
transducer

Vout

Input
Filter

Instrumentation
amplifier

G

to AD converter

In addition to the RS485 reset there is a logic power-up reset, which holds for approximately 500
ms regardless of the state of the RS485 reset. A time constant determines the power-up reset time.
The power-up reset also prevents the module from sending data to the Module Bus. The data
transmission rate is 500 kbps.

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Datex-Ohmeda S/5 monitors

Isolated section

r
o

Receive data

sess
o

Send

r

send

p
e

dat

/receive

Reset

a

Opto isolation

Receive data

Send data

Reset

RS485
Driver

send/r

RS485
Driver

Data

NDa

eceive

Reset in

NReset in

)

nit

s

t

a

u
l

ra

bu
e

nt
ce

to

(modul

to modul

Patient

Isolation

Figure 5 Serial communication and opto isolation sections

There are two opto isolators, one for data and one for the reset signal. Signals are processed on
logical high-low levels even though the output of the opto isolators in the isolation section are
analog signals.

The reset line is an open collector type with a pull-up resistor so that the microprocessor is able to
use its internal watch-dog function.

Power supply section

The module isolated supply voltage is developed from the +15 Vdirty (non-isolated) supply from
the Central Unit power supply.

The isolated power supply is a switched-mode circuit, where an FET switch is controlled by an
oscillator using a bipolar timer. The frequency of the oscillator is approximately 30 kHz with a pulse
ratio 50 %; switching of the FET switch is slow to suppress spurious interference.

A special isolation pulse transformer is used in the circuit. The transformer secondary circuit uses
normal linear regulators except for +5 V which uses a low drop type linear regulator.

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