Hollis Prism 2 User manual

NO LIMIT
Ver. 2 Displays
And Electronics
User Manual
REV.2

ii |
!DANGERS: are indicators of important information that if ignored would
lead to severe injury or death.
!WARNINGS: are indicators of important information that if ignored could
lead to severe injury or death.
!CAUTIONS: are indicators of information that if ignored may lead to minor
to moderate injury.
!NOTES: indicate tips and advice that can inform of features, aid assembly,
or prevent damage to the product.
This is the operations manual for the
Hollis PRISM 2 Gen. 2 Displays and Electronics
This manual, specifications and features of the PRISM 2
are proprietary and copyright Hollis Inc., 2013.
DiveCAN® is registered to Shearwater Research.
This document cannot be copied or distributed without
the prior agreement and authorization from Hollis Inc.
All information contained is subject to change. Contact the
manufacturer for the latest information. www.hollisgear.com
The PRISM 2 is manufactured in the USA by Hollis Inc.,
2002 Davis Street, San Leandro, CA 94577. USA
Ph [phone]
EC Type approved by SGS UK Ltd. Weston-super-Mare.
BS22 6WA. Notified Body No. 0120.
Testing conducted by ANSTI Test Systems. Hants.
To ensure your user information is up to date. Please check
www.hollisgear.com for updates to this manual.
DANGERS, WARNINGS, CAUTIONS, AND NOTES
Pay attention to the following symbols when they appear throughout this docu-
ment. They denote important information and tips.
Document Control Number: 12-4106 Rev. 2
Publish Date: 12/12/13
Written by: Bruce Partridge
Contributor: Kevin Watts

| iii
!WARNING:
GENERAL SAFETY
No person should breathe from, or attempt to operate in any way, a Hollis PRISM 2 rebreather,
or any component part thereof, without first completing an appropriate Hollis Certified user-
training course.
Further, no PRISM 2 diver should use a Hollis PRISM 2 without direct Hollis instructor supervision until
they have mastered the proper set-up and operation of the Hollis PRISM 2 rebreather. This includes
new PRISM 2 divers as well as PRISM 2 certified divers who have been away from diving for an ex-
tended period of time and would benefit from an instructor-led refresher course to regain skills mas-
tery of the Hollis PRISM 2. Failure to do so can lead to serious injury or death.
The PRISM 2 rebreather can, as with any closed circuit breathing loop, circulate breathing gas that
may not contain a sufficient quantity of oxygen to support human life. The breathing gas within the
Hollis PRISM 2 loop must be closely monitored and manually maintained with a safe oxygen content
by you (a properly trained and alert user) at all times.
The PRISM 2 computer-controlled addition of oxygen to the breathing loop is intended as a fail-safe
back-up system to you, the primary controller. If you (either knowingly or by inattention) allow the
PRISM 2 computer to control oxygen addition to the breathing loop at any time, you are diving outside
the principals of your PRISM 2 training - assuming any and all possible risk.
!WARNING:
DECOMPRESSION
Diving with rebreathers and/or diving mixed gases and/or performing staged decompression
dives and/or diving in overhead environments greatly increases the risks associated with scuba
diving.
This computer is capable of calculating deco stop requirements. These calculations are predictions of
physiological decompression requirements. Dives requiring staged decompression are substantially
more risky than dives that stay well within no-stop limits. They require specific training in CCR decom-
pression procedures.
GENERAL SAFETY
STATEMENTS + WARNINGS

iv |
!WARNING:
COMPUTER SOFTWARE
Never risk your life on only one source of information. Use a second computer or tables. If you choose
to make riskier dives, obtain the proper training and work up to them slowly to gain experience. Always
have a plan on how to handle failures. Automatic systems are no substitute for knowledge and training.
No technology will keep you alive. Knowledge, skill, and practiced procedures are your best defense.
!WARNING:
PROPER BATTERIES
Only name-brand batteries (such as Duracell, Eveready; Saft) may be used to power the PRISM 2. Off-
brand / Discount batteries have been found to vary greatly in quality of materials from batch to batch
(and even piece to piece!) Therefore they may not perform as expected, or be capable of consistently
delivering the power required to drive the components, despite battery voltage levels reported by a bat-
tery voltage meter.
While off-brand / discount batteries are perfectly acceptable for use in toys and flashlights, they
have no place in life support gear and must never be used to power any component of your
PRISM 2.
Because of the potential rapid drop-off of charge from rechargeable batteries, rechargeable
batteries are not recommended for use with your PRISM 2 rebreather and must not be used.
!WARNING:
It is extremely important that you read this manual and understand completely before attempting to use
your new Hollis dive computer.
Diagram showing rapid discharge of non-branded batteries,
which in life support gear can result in unnecessary hazards.
The full article, “Are Expensive Batteries Worth The Extra
Cost?” is available at Wired.com
Image courtesy of Rhett Allain, Wired

| v
!WARNING:
Each numeric and graphic display represents a unique piece of information. It is imperative that you
understand the formats, ranges, and values of the information represented to avoid any possible misun-
derstanding that could result in error.
!WARNING:
As with all underwater life support equipment, improper use or misuse of Hollis computers can result in
serious injury or death.
!WARNING:
Helium features are intended for use by divers who have successfully completed a recognized course in
CCR diving with Trimix mixtures, and have knowledge of the potential risks and hazards of diving CCR
with Trimix.
!WARNING:
Diving at high altitude requires special knowledge of the variations imposed upon divers, their activities,
and their equipment by the decrease in atmospheric pressures. Hollis recommends completion of a
specialized Altitude training course by a recognized training agency prior to diving in high altitude lakes
or rivers.

vi |
General Safety Statements & Warnings
PART 1
WELCOME
PART 2
DIVECAN®
SECTION 1
WHAT IS DIVECAN®?
SECTION 2
DIVECAN®ADVANTAGES
PART 3
HUD (HEADS UP DISPLAY)
SECTION 1
INTRODUCTION
SECTION 2
PHYSICAL DESCRIPTION
SECTION 3
READING THE PPO2
SECTION 4
DETECTING ABNORMAL PPO2
SECTION 5
ERROR DISPLAYS
SECTION 6
ADVANCED OPTIONS
PART 4
WRIST DISPLAY
SECTION 1
BUTTONS AND ACTIVATION
SECTION 2
THE MAIN SCREEN
SECTION 3
INFO SCREENS
SECTION 4
MENUS
SECTION 5
MENU STRUCTURE
SECTION 6
BASIC SETUP
SECTION 7
SIMPLE DIVE EXAMPLE
iii-v SECTION 8
COMPLEX DIVE EXAMPLE
SECTION 9
DECOMPRESSION &
GRADIENT FACTORS
SECTION 10
GRADIENT FACTORS EXPLAINED
SECTION 11
VPM-B / GFS EXPLAINED
SECTION 12
MENU REFERENCE
SECTION 13
FIRMWARE UPLOAD &
DIVE LOG DOWNLOAD
SECTION 14
CHANGING THE BATTERY
SECTION 15
TISSUES CLEARED
SECTION 16
ERROR DISPLAYS
SECTION 17
COMPLEX DIVE EXAMPLE
PART 5
POST-DIVE CARE
SECTION 1
STORAGE, MAINTENANCE, & SERVICING
PART 6
SPECIFICATIONS
SECTION 1
DIVECAN®HUD
SECTION 2
WRIST DISPLAY
PART 7
TERMS & FCC
SECTION 1
GLOSSARY
SECTION 2
FCC WARNING
TABLE OF CONTENTS

| vii| vii
Your PRISM 2 utilizes the best CCR electronics package available today to
monitor and control operation. You will find the electronics are reliable and
simple to use.
This manual will walk you through all the basics as well as the subtleties of
the displays and electronics. For complete understanding of the PRISM 2,
use this manual in conjunction with the main PRISM 2 User Manual doc. #
12-4072.
Remember that it is far easier and safer to learn what all the different
alarms, warnings, and indications mean before you jump in the water. If
after reading this manual you are not clear on any topics, ask your PRISM
2 instructor for further information.
Welcome!
PART 1 . SECTION 1

2 |
DiveCAN®is a digital communications standard developed specifically for
rebreathers.
Divecan®
What is divecan®?
DiveCAN
®
DiveCAN
®
Monitor BusControl Bus
LED HUD
Monitor Port
Wrist Display
Future Device
(Optional) Auxiliary Port
Handset Port
Rebreather
CONTROLLER
SOLO
( SOL &
O xygen
electronics)
OBOE
( O xygen
BO ard
E lectronics)
DiveCAN® connections allow rebreather components to communicate.
A minimum configuration has a Control Bus with a handset connected to
rebreather electronics (“bus” is a term used to describe the connections
between communicating electronic modules).
Depending on your rebreather, a secondary Monitor Bus may be used.
This independent bus provides backup PPO2monitoring in the event of
a failure of the primary control bus.
Spare auxiliary ports may be included for additional devices or future ex-
pansion. Even if your rebreather does not have a spare port, additional
devices can be added with the use of Y-cables.
DiveCAN® devices connect together using specially designed underwa-
ter connectors. This allows easy disconnection of devices for upgrades,
repair, and travel.
PART 2 . SECTION 1

| 3
The DiveCAN® standard was designed to improve rebreather electronics.
It offers the following advantages over the previous generation of analog
wiring:
Robust error-checked communications. A message is either received
correctly or it isn’t. Compare this with analog wiring where corrosion or
poor connections can result in incorrect data being used. Upgradable and
expandable. As new technologies are introduced, they can be plugged
into existing rebreathers. Components (handset, HUD, etc) can be easily
removed for travel, repair, backup, and upgrades.
Modular design compartmentalizes critical functions for redundancy. For
example, the Solenoid and Oxygen electronics (SOLO) can measure and
inject oxygen independently of the handset. If the handset is unplugged
or damaged during a dive, the SOLO will continue to control loop PPO2.
Independent SOLO operation is not designed to function at the surface to
avoid continuous solenoid firing, gas loss, or battery drain if disconnected
at the surface.
!WARNING: SOLO operation independent of the wrist display ONLY
functions while the rebreather is submerged in a dive. Accidental
disconnection of the wrist display at the surface will result in loss
of solenoid control. This could lead to an unsafe oxygen level.
Always inspect the unit and perform required checklists before
breathing on the rebreather.
The DiveCAN® connectors are miniature versions of the underwater con-
nectors used in the oil and gas industry (Fig. 2.1). They are robust and
rated to 2000 ft underwater. The index lines must be aligned to plug the
male connector into the female connector.
Additionally, The connectors utilize a locking sleeve to prevent accidental
separation during casual use. Each sleeve is held in place by two O-rings.
To prevent expensive damage, they are designed to break free under
extreme strain, i.e. hooking a cord on a boat ladder during water entry. To
remove the sleeves, slide the two retaining O-rings off of the locking sleeve
(Fig. 2.2). Then spread the sleeve at the seem while pulling it off of the
connectors (Fig. 2.3). Installation is the reverse.
!WARNING: DO NOT dive without the locking sleeves properly
installed and retained with O-rings as shown (Fig. 2.4).
divecan® Advantages
PART 2 . SECTION 2
Fig. 2.2
Fig. 2.3
Fig. 2.4
Male Connector
Female Connector
Fig. 2.1

4 |
The Heads-Up Display (HUD) is a rebreather partial pressure of oxygen
(PPO2) display device.
!WARNING: Read the manual. Your life depends on always knowing
the loop PPO2when diving a rebreather. DO NOT make assump-
tions about how this device works, even if you have used a pre-
vious generation HUD. Some of the blink patterns and warnings
have changed from previous PRISM 2 HUD versions.
FEATURES
• PPO2display from 3 oxygen sensors.
• Modified Smither’s code blink pattern.
• Bright light emitting diodes with vibrant colors.
• Color-blind blink pattern (optional setting).
• Wet contacts for automatic turn-on and user commands.
• Option to flip orientation - can be positioned on either side of the re-
breather mouthpiece.
• DiveCAN® communications interface for robust data transmission and
easy upgrades, disassembly and repairs.
• Bright red end-cap LED for buddy warnings.
• Automatic brightness control optimizes viewing in all conditions.
• Red color only used for unsafe PPO2warnings.
hud (heads up display)
Introduction
PART 3 . SECTION 1

| 5
LED array
An array of colored light emitting diodes (LEDs) blink to display PPO2.
For color-blind users, there is an optional blink pattern that uses position
only to display PPO2.
Buddy warning light
The buddy warning light pulses red when PPO2is outside a safe range.
Wet contacts
Putting the wet contacts in water or touching them with a wet finger will
turn on the HUD. The wet contacts are also used to enter commands.
DiveCAN® cable
The DiveCAN® cable provides a robust, disconnectable connection to the
rebreather.
Physical description
LED array
DiveCAN® cable
Buddy warning
light
Wet contacts
PART 3 . SECTION 2

6 |
LED ARRAY DESIGN
The default blink pattern is a modified Smither’s code, similar to the previ-
ous generation HUD. See PART 3 Section 7 for the optional colorblind
mode.
What does the HUD display?
PPO2is displayed in units of absolute atmospheres (ata) with a resolu-
tion of 0.1 ata. For the purposes of this HUD, this can be considered
the same as Bar. i.e. 1 ata ≈1 Bar.
Each column displays PPO2from one O2Sensor (Fig. 3.1).
There are four rows of LEDs.
Each row has an associated color:
Top: red
Upper Middle: green
Lower Middle: yellow
Bottom: red
!NOTE: For the purposes of this manual, a blinking LED is drawn
with lines emanating from it. An LED that is on-steady is drawn
solid. An off LED is not drawn (Fig. 3.2).
Reading the pp02
Column 1/ Sensor 1 Column 2/ Sensor 2 Column 3/ Sensor 3
Fig. 3.1
Red LED
is blinking
Green LED
is on solid
All other LEDs
are off in this
example
Fig. 3.2

| 7
MODIFIED SMITHER’S CODE
This is the default blink pattern. Blinks of color are used to display PPO2.
Every 5 seconds a blink cycle begins.
The blink pattern depends on the PPO2range:
PPO2Range HUD Display Blink Pattern
Above 1.6
Top-red blinks once
for each 0.1 above 1.0
e.g. 1.7 = 7 top-red
blinks
1.1 to 1.6
Green blinks once
for each 0.1 above 1.0
e.g. 1.3 = 3 green
blinks
1.0
1.0 = Green and yel-
low blink once to-
gether.
0.4 to 0.9
Yellow blinks once
for each 0.1 below 1.0
e.g. 0.7 = 3 yellow
blinks
Below 0.4
Bottom-red blinks
once
for each 0.1 below 1.0
e.g. 0.2 = 8 bottom-
red blinks
The above can be summarized as follows:
Top-red blinks when above 1.6
Green blinks once for each 0.1 above 1.0
Green and yellow blink together once for 1.0
Yellow blinks once for each 0.1 below 1.0
Bottom-red blinks below 0.4
PART 3 . SECTION 3

8 |
The modified Smither’s code has some nice attributes that grab attention
in abnormal or unsafe situations.
PPO2DEVIATIONS FROM SETPOINT
A typical rebreather PPO2setpoint will be about 0.7 to 0.8 for the low set-
point, and 1.2 to 1.3 for the high setpoint.
Therefore, when the loop is at setpoint, you will expect to see 2 to 3 blinks
per 5 second cycle.
If the “light density” changes (i.e. you are seeing more or less blinks), then
the setpoint is off target.
This change in light density can grab your attention even if you have tuned
out the blinking of the LEDs. Of course, we recommend paying attention at
all times.
UNSAFE PPO2
If the PPO2falls below 0.4 or rises above 1.6, you will be seeing a lot of red
blinking.
Since red is not used at all in the normal safe PPO2range, the presence of
red is a clear signal that something is wrong.
BUDDY RED WARNING LIGHT
The sole function of the buddy red warning light is to alert that the PPO2is
outside the range of 0.4 to 1.6. If any O2cell is outside this range then the
warning light turns on.
If the buddy warning light comes on, check your PPO2, consult your hand-
set, and deal with the problem.
!NOTE: THE BUDDY WARNING LIGHT COMES ON IF ANY OF THE
THREE O2SENSORS IS READING UNSAFE ON THE LED ARRAY
(FIG. 3.3).
Detecting abnormal PPO2
Fig. 3.3
PART 3 . SECTION 4

| 9
Commands are entered using the wet contacts. Activate the wet contacts
by connecting them with a conductive material (Fig. 3.4).
This can be:
• A wet finger
• Water
• A coin
• A piece of metal, etc.
TURNING ON
Turn the HUD on by holding the wet contacts. It may take up to 5 seconds
to turn on. Keep holding until the LEDs turn on.
After turning on, each LED will light up briefly. Use this time to verify that
each LED, including the buddy warning light, works properly.
!WARNING: DO NOT use the HUD if any of the LED’s are not work-
ing.
After each LED has been turned on, an “UP” arrow will briefly display. This
indicates which orientation the HUD has been set to use. Orient the HUD
so the arrow points up as shown (Fig. 3.5).
Basic commands
Wet contacts
Wet finger
Fig. 3.4

Fig. 3.5
PART 3 . SECTION 5

10 |
DOUBLE TAPPING
Enter commands by double-tapping the wet contacts (3.6). It should take
about 1 second to complete the double-tap.
!NOTE: Taps that are too fast or too slow will be ignored. Saying
“tap-tap” aloud at a normal pace will help get the timing right.
After the first double-tap, the bottom two LEDs of column 1 will blink. This
is “command column 1”. Each double-tap advances the command column
by one position (Fig. 3.7).
Execute the command by holding the wet contacts for 3 seconds while the
command column is blinking.
A command column will time-out, returning to the regular PPO2display
after a few seconds of inactivity. Also, double-tapping when on the last
command column will return to the regular PPO2display.
MENU
The menu command will be explained further in the PART 3 Section 7
“Advanced Options”.
The Advanced Options menu is entered by holding for 3 seconds while on
command column 1. This must be done three times to enter the advanced
options menu.
!NOTE: The Advanced Options Menu must be selected three times.
This was designed intentionally to prevent accidental changing of
options. Further instruction can be found in the Advanced Options
section.
“Tap”
“Tap”
Wet finger
Fig. 3.6
MENU TURN-OFF
CALIBRATE
Fig. 3.7

| 11
TURNING OFF
Turn off by holding the wet contacts for 3 seconds while on command
column 2, as shown (Fig. 3.8).
The complete turn off sequence is:
1. Double-tap to enter 1st command column (MENU).
2. Double-tap again to advance to 2nd command column (TURN OFF).
3. Hold for 3 seconds.
4. While holding, the 2nd column LEDs count up. They blink twice to
indicate the command has executed.
5. HUD shuts off.
!NOTE: Turn off the HUD when not in use to save battery power.
The HUD will turn off by itself after 30 minutes of inactivity.
However, the HUD will not turn-off if the wet contacts detect the presence
of water. Ensure the wet contacts are dry before putting the HUD into stor-
age.
!NOTE: The HUD contacts must be dry to prevent accidental activa-
tion and battery use.
CALIBRATE (PPO2)
Perform the PPO2calibration by holding the wet contacts for 3 seconds
while on command column 3 (Fig. 3.9).
The complete calibration sequence is:
1. Flood the loop with pure oxygen as per training and PRISM 2 manual.
2. Double-tap to enter 1st command column (MENU).
3. Double-tap again to advance to 2nd command column (TURN OFF).
4. Double-tap again to advance to 3rd command column (CALIBRATE).
5. Hold for 3 seconds.
6. While holding, the 3rd column LEDs count up. They blink twice to indi-
cate the command has executed.
7. The green and yellow LED rows then count up to indicate the calibration
is in progress.
8. Once the calibration completes, the HUD will return to the regular PPO2
display.
MENU TURN-OFF
CALIBRATE
Fig. 3.8
MENU TURN-OFF
CALIBRATE
Fig. 3.9
!WARNING: The HUD ONLY calibrates at a PPO2of 1.0 ata. This
means it assumes pure oxygen is used for the calibration, and it is
performed at sea-level. Errors will be introduced if this is not the
case. To adjust for altitude see the following section.
PART 3 . SECTION 5

12 |
ADJUSTING FOR ALTITUDE
Oxygen sensor calibration results are not stored in the HUD itself. Instead
it is stored in the rebreather electronics contained in the PRISM 2 scrubber
head. Using the advantages of the DiveCAN® system, you can access and
adjust for altitude in a clever way.
To calibrate at altitude, unplug the HUD DiveCAN® cable, and temporarily
replace the HUD with a device that can calibrate at altitude (for example
the wrist display handset). Perform the calibration with the alternate device.
Then switch the devices back to their proper connections.
!NOTE: To follow the proper altitude calibration procedure us-
ing the wrist display, see the Display Settings → Altitude section
(PART 4 Section 12) in this manual.
!WARNING: Remember the HUD and wrist Display sides of the
PRISM 2’s internal electronics are separate. Each side will still
need to be calibrated separately because the wrist display, like
the HUD, does not store the calibration in the wrist display.

| 13
The following error conditions may occur:
FAILED PPO2CALIBRATION
HUD Display Description Troubleshooting
Top and bottom red
LEDs on solid
All O2sensors have
failed calibration
A good O2sensor is expected to
output between 30 mV to 70 mV
in pure oxygen at sea-level.
A sensor that does not meet
these specs fails calibration. Fix
the problem (e.g. replace the
sensors) and recalibrate.
Top and bottom red
LEDs on solid (1 column)
Other columns normal
One O2sensor has
failed calibration.
In this case sensor
#3 has failed.
It is possible for some sensors to
pass calibration, while others fail.
This indicates which sensor is
faulty.
See above for troubleshooting.
DO NOT dive unless all sensors
are functional.
NO COMMUNICATIONS
HUD Display Description Troubleshooting
Four corners blinking
No DiveCAN®
Communications
Ensure the DiveCAN® cable
connector is securely fastened.
Contact Hollis for service.
Error displays
PART 3 . SECTION 6

14 |
LOW BATTERY
HUD Display Description Troubleshooting
After turn on, the yellow
row stays on for 30 seconds
Battery is low and
should be replaced
Replace the battery (or batteries)
for the monitoring/HUD
electronics.
See the instructions for your
rebreather for battery type and
location.
The HUD does not have its own battery. It receives power from electronics
located inside the rebreather.
A typical rebreather will have two independent battery systems. One bat-
tery system for the primary oxygen controller side, and one battery system
for the backup monitoring side. On the PRISM 2 This HUD is part of the
backup monitoring side.
The HUD does not set a specific voltage at which the battery should be
changed. The HUD just receives a message from the rebreather electron-
ics that says the battery is low and should be changed.
Please read and follow the instructions on how to change the batteries
found in the PRISM 2 User Manual (Doc. # 12-4072).