POSEIDON M28 User manual

POSEIDON M28
USER MANUAL 2.1

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POSEIDON M28 USER MANUAL
Table of Contents
Table of Contents..................................................................................................1
Conventions Used in this Guide.............................................................................4
Preface .................................................................................................................6
Conformance with CE Requirements .....................................................................7
Chapter 1 – Overview
Box content................................................................................................................ 8
An overview of the M28.........................................................................................9
Button function ...................................................................................................10
First start-up .......................................................................................................11
Monitoring the Display.........................................................................................12
Top bar ...............................................................................................................13
Center area.........................................................................................................14
Chapter 2 – The menu system
General apps............................................................................................................ 19
Dive app .............................................................................................................20
Text message box ...............................................................................................22
Open Circuit (OC) Mode Menu.............................................................................25
Open Circuit (OC) Mode after Dive Start...............................................................26
Setpoint and CPOD Closed Circuit (CC) Mode Menu ...........................................28
Setpoint and CPOD Closed Circuit (CC) Mode Menu after Dive Start....................29
SE7EN Closed Circuit (CC) Mode Menu...............................................................31
SE7EN Closed Circuit (CC) Mode after Dive Start.................................................32
Gauge Mode.......................................................................................................33
Dive log app........................................................................................................34
Planner app ........................................................................................................35

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POSEIDON M28 USER MANUAL
Picture app .........................................................................................................37
System app ........................................................................................................38
System app - menu tree......................................................................................39
Force fw update..................................................................................................40
Land app ............................................................................................................42
Settings ..............................................................................................................43
Update SE7EN rmware through the M28............................................................49
Chapter 3 – M28 Alarms
Alarm signals............................................................................................................ 51
Abort and open circuit alerts, DO NOT DIVE alert ..................................................... 52
General alert, Stop alert............................................................................................ 53
Electronics alert, Alarm message.............................................................................. 54
Decompression ceiling alert...................................................................................... 55
Descend arrow......................................................................................................... 56
Mouthpiece position ................................................................................................. 57
Dive alarms............................................................................................................... 58
Connection status alarms ......................................................................................... 60
Technical alarms....................................................................................................... 62
Chapter 4 – Wi-Fi Access Point
Home ....................................................................................................................... 63
Dive Log................................................................................................................... 64
Redbox log............................................................................................................... 65
Picture...................................................................................................................... 66
Screen Dump ........................................................................................................... 67
Firmware Update...................................................................................................... 68
System..................................................................................................................... 69

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POSEIDON M28 USER MANUAL
Chapter 5 - Recharge the M28 battery
Changer cable ....................................................................................................70
Chapter 6 - Bungee cord, Care and maintenance
Bungee cord preparation.....................................................................................71
Care and maintenance ........................................................................................72
Chapter 7 - Protective Cover & Screen Protection
Protective Cover and Screen Protection...............................................................73
Chapter 8 - Technical specications
Dimensions and weight .......................................................................................75
Operating conditions, Depth gauge .....................................................................76
Appendix 1 Symbols
Alarm and Warning symbols ................................................................................77
Display states and views, Connecting symbols ....................................................78
Appendix 2
Rebreather connectivity examples .......................................................................79
Support and Feedback page...............................................................................80

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POSEIDON M28 USER MANUAL
Conventions Used in this Guide
This User Guide is NOT intended for use as a training manual, or in any way as
a substitute for proper training through a legitimate training agency approved
by Poseidon AB. It is only intended to provide basic information concerning the
Poseidon M28.Throughout this Guide, special alert boxes have been inserted to
draw attention to critical information. Three levels of alerts are used in conjunction
with color-coded symbols, as follows:
DANGER:
Alert boxes that are RED contain extremely critical
information related to the safety and well-being of the diver.
Failure to comply with information contained in these boxes
could lead to serious injury or death.
WARNING:
Alert boxes that are YELLOW contain vital information
that may impact a diver’s safety and/or proper function of
the Poseidon M28. Though generally not life-threatening,
information contained in these boxes should not be ignored.
IMPORTANT:
Alert boxes that are BLUE contain important information
about the proper care and maintenance of the Poseidon M28,
and that may increase diver comfort or enhance enjoyment
during dives.

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POSEIDON M28 USER MANUAL
No part of this book may be reproduced or transmitted in any form or by
any means, electronic or mechanical, including photocopying, recording or
by any information storage retrieval system, without permission in writing
from an authorized representative of Poseidon Diving Systems AB.
Text, photographs and gures copyright © 2022 by Poseidon Diving Systems AB
ALL RIGHTS RESERVED Manual Version 2.1 - February 2022
DANGER:
The Poseidon M28 is an advanced dive computer, which
functions in a manner distinctly different from traditional dive
computers. Do not attempt to use the Poseidon M28 without
a thorough and complete working knowledge of the material
contained in this manual. Careless use of the Poseidon M28 can
lead to decompression sickness or death in any environment
without any prior warning symptoms.
Careless use of the Poseidon M28 at depths underwater greater
than 200 msw (meters of seawater) [656 fsw (feet of seawater)]
can lead to failure of the computer without any prior warning.
This conditions can cause serious injury or death. The Poseidon
M28 is equipped with sophisticated electronic control systems,
which will allow a properly trained user to avoid these situations.
It is the user’s responsibility to attentively monitor these systems
when using the Poseidon M28 and to have a working knowledge
of the abort procedures should a problem arise. The computer
calculates decompression stops. These calculations are based
on available knowledge and is provided as a guidance and are
not exact physiological data. Remember that this device can fail,
due to mechanical failure, rmware issues or other technology.
Do not depend upon this device solely, use also redundant tools
to manage your dive in case of a total failure of this computer.
Use at your own risk.

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POSEIDON M28 USER MANUAL
Preface
A WARM THANK YOU!
We are grateful and proud that you choose us as the supplier of your dive gear.
We hope that it will give many good memories along the way and you can look back
on this day as a day to remember when you unwrapped your new dive computer.
Features:
• High performance OC and CCR dive computer
• Feature-rich graphics thanks to a the 2.8” TFT LCD Color Display
• Highly intuitive user interface with dual button control
• Enhanced SE7EN with the M28’s Rebreather Management System
• Dive-by-Wire™ integration with Poseidon Pod Systems, HUD, HP and other
sensors
• Dual decompression algorithm (DCAP and Bühlmann ZHL16C with gradient
factors)
• Dynamic interface; Wi-Fi access point.
• Depth rated to maximum 200m / 656ft
• Upgradable rmware

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POSEIDON M28 USER MANUAL
Conformance with CE requirements
European diving depth gauge standard, i.e. EN 13319.
EN61000 (emission & immunity).
FCC 47 CFR. This device complies with Part 15 of the FCC Rules. Operation is
subject to the following two conditions: This device may not cause harmful
interference, and this device must accept any interference received, including
interference that may cause undesired operation.
This product has been tested to comply with FCC standards.
Poseidon Diving Systems AB is
certied according to ISO 9001

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POSEIDON M28 USER MANUAL
Chapter 1 Overview
This chapter describes the steps to assemble and prepare the Poseidon M28
for diving. The M28 is a modular device with subsystems.
Box content:
• M28 computer • Travel pouch
• Storage case • Charger cabel
• Bungee cord • Quick reference guide

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POSEIDON M28 USER MANUAL
The gure illustrates these locations and the main features of the Poseidon M28.
The “back” of the M28 is the side opposite to the display side.
Following is a brief description of each of the major components.
An overview of the M28
Serial number
CAN cable connector
(with blind Plug BUS) Dual button interface
Color display
Light sensor
Indicator light (LED)
Attachment for
bungee cord or band
Attachment for
bungee cord or band
Depth sensor &
temperature sensor
Blind Plug BUS

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POSEIDON M28 USER MANUAL
Button function
UP
DOWN
ENTER
Once the M28 is fully powered up, it is ready to use. To operate and access functions,
use the two buttons. The interface is very intuitive to use and is described in the gure
below. Press both buttons simultaneously to enter the menu system, then scroll up or
down and press both buttons simultaneously again to select the highlighted option.
After 30 seconds of inactivity, the M28 dismisses the menu and returns to the previous
screen.

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POSEIDON M28 USER MANUAL
First start-up
To start the M28 press both buttons simultaneously
Once the M28 has been started, the indicator light will ash green to indicate that the
M28 computer is turning on. This will be followed by a start-up screen with a visible
Poseidon logo. Please note that the time to visible start-up screen can vary in length.
After a few seconds this screen will be replaced by the Dive app.
DANGER:
Do not attempt to conduct a dive until the system has
successfully completed its start up procedure. Diving in spite
of a failed start up is extremely dangerous, and could lead to
serious injury or death.

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POSEIDON M28 USER MANUAL
Monitoring the Display
ENTER
Most of the information concerning the status of the dive and various parameters
is communicated to the diver via the Display. It consists of a 2,8” TFT color QVGA
screen, and provides the diver with important information concerning sensor readings,
system messages, decompression status, and other data during the course of the
dive. It is extremely important that all Poseidon M28 divers understand how to read
the information contained in the Display, particularly concerning various alarm condi-
tions. Before even turning the Poseidon M28 on, it is useful to understand the general
layout of the Display, and the logic behind how the information is organized.
DANGER:
If the Display screen is ever blank or freezes during a dive,
immediately commence an abort to the surface.
Failure to do so could lead to serious injury or death.
On the following pages the various application modes will be discussed, as well as the
menu structure. The “Dive” app is the initial app after start up.
This app is automatically visible after an initial safety message that can be conrmed
by pressing any of the two buttons.

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POSEIDON M28 USER MANUAL
Top bar
The top bar is visible in all apps and indicates the selected app, connecting status,
clock and status of the battery.
Connection status
Clock or current dive mode

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POSEIDON M28 USER MANUAL
Center area
The M28 gives the diver the option to select what information that shall be
displayed in the center area. You can cycle through the available center area
content using the up or down key. The available content options varies with the
selected App and Dive mode.
Clock ppO2 gauge Ascent/Descent
rate
Compass
and Gyro
DCAP
tissue graf
Bühlmann
tissue graf Cylinder pressure
and gas
Battery status Temperature
Setpoint
Compass Onboard gas supply

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POSEIDON M28 USER MANUAL
Clock. Displays the same time and time zone as the Top Bar. Adjustments of the
clock´s time are made in settings.
ppO2gauge. Shows one or more ppO2NEEDLES depending on the number of
oxygen sensors connected. Long white needle for the main sensor, gray tip for
secondary sensor, blue tip for the third sensor. The setpoint scale rotates such that
the current setpoint value is always below the red arrow marker at the top and always
pointing up towards the red arrow marker on the top. This means that when the
setpoint is changed the setpoint scale will rotate to reect the change. This will help
the diver to quickly understand if the ppO2of the gas in the breathing loop is too high
or too low at the current depth. The BLUE DOT indicates the oxygen content of the
diluent gas tank, while the RED DOT indicates the content of the oxygen gas tank.
This information is useful to a technical diver when performing a loop ush.
Ascent/Descent rate. Shows Ascent and Descent rate per minute. Unit (m/min or ft/min)
is congured in Settings / Depth unit. Ascent rate alarm will start when Ascent speed
is higher than 9 meters/minute. There is no descent rate alarm, but remember that
ppO2in the gas will change when depth is changing.

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POSEIDON M28 USER MANUAL
Compass and Gyro. Displays compass heading and Gyro attitude. The compass is
tilt independant.
This symbol appears when the compass is not calibrated.
Calibrate by rotating the computer slowly in all directions illustrated by the
gures below until the symbol disappears.
This symbol indicates that the compass is exposed
to ambient stress eld and can be misleading.

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POSEIDON M28 USER MANUAL
Setpoint which are used by SE7EN and the M28 to determine the sliding setpoint at
the current depth. Setpoint low and Setpoint high can be recongured from the Dive
app menu in SE7EN, CPOD and Setpoint dive mode.
DCAP or Bühlmann tissue value graph.
Indicates the gas load of the tissues used in the decompression model.
Bars representing gas load in fast tissues on the left side and slow on the right.
Nitrogen (N2) is the upper part of the graph growing upwards, while helium (He) is
the lower part of the graph, growing downwards. The intent of this graph is to give an
overview of the current gas load for the tissues in the decompression model.
Cylinder pressure and gas. Displays the conguration of the currently selected gas
tank in terms of tank volume, tank pressure rating, oxygen fraction and helium fraction.
Units used for pressure and volume can be congured in Settings.

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POSEIDON M28 USER MANUAL
Battery status. Displays the battery status (% of capacity when the
battery is fully charged). If a SE7EN is connected, the M28 also displays the SE7EN
battery status. The battery icon in the Top Bar always shows the battery status for the M28.
Temperature. Displays the current water temperature when you dive.
If SE7EN is connected also displays the temperature in your breathing loop.
The unit (°C or °F) can be congured in Settings / Temperature unit.
Onboard gas supply. Displays the current cylinder pressure together with the corres-
ponding gas volume that would be available at one bar environmental pressure for the
SE7EN onboard oxygen cylinder and the SE7EN onboard diluent cylinder.

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POSEIDON M28 USER MANUAL
Chapter 2 The menu system
Most of the features and functionality of the M28 are accessed through the menu
system. To activate the menu system, simply press both buttons simultaneously.
The menu now becomes visible, the top three menu items are always the same,
starting with “Exit menu” that takes you back to the current application screen
“Settings” that makes it quick and easy to access key settings and “Apps” that
takes you into the various functions of the M28 shown in gure below.
The content below the “Apps” menu item is always related to the App that you
currently use. In this example having the Land app activated the menu will only
show the Stopwatch function. In the following Apps sections we will discuss the
application specic content.
Static Menu items
APP mode
dependent content
Press enter to activate the menu,
scroll up or down and press enter to select.
If no menu item has been selected within 30 seconds,
the menu is closed automatically.