A&D 2 Plus - Manual (Page 2)

INTRODUCTION
Congratulations on the purchase of your Monitor 2 Plus (M2+) dive
computer. Our designers have condensed important dive planning
information into a user-friendly dive instrument. By combining
graphics with bold alphanumerics, we have created an easy-to-use
computer that provides dive data at a glance.
As with all diving equipment, it is important to understand the
features and functions of the M2+. Before using the M2+, it is
essential to read this manual in its entirety. Contained within this
easy to read manual are illustrations to aid you in the complete
understanding of the computer.
Section 1 instructs you on diving with the M2+, including pre-dive
activation, descriptions of underwater displays, functions after the
dive, and diving at altitude. Section 2 shows you how to recall the
dive memory. Instructions on planning a future dive are given in
Section 3. Care & Maintenance tips are covered in Section 4. Lastly,
the reference section contains the technical specifications and a
description of the algorithm.
WHAT IS A “DIVE COMPUTER”
DEFINITION OF COMPARTMENTS
A dive computer is an instrument that mathematically simulates the
absorption and release of nitrogen by hypothetical tissue types in the
human body. These hypothetical tissues are commonly referred to as
“compartments.” Each compartment absorbs and releases nitrogen at
different rates. The M2+ tracks these compartments constantly,
providing you with up-to-the-minute decompression information.
MULTI-LEVEL DIVING
If you use, or have used, dive tables you know the total amount of
time you can stay under water is based on the maximum depth
reached during the dive. Dive tables, such as the U.S. Navy dive
tables, assume that you immediately descend to a single depth, stay
at that depth for the duration of the dive, then immediately surface
from that depth. This type of dive profile is referred to as a rectangu-
lar dive profile (figure 1). In reality, however, most recreational
divers go to the deepest depth first and make a gradual ascent to the
surface. This type of dive profile is referred to as a multilevel dive
profile (figure 2).
Multilevel diving is where the M2+ excels. By continuously calculat-
ing the nitrogen absorption/release of all the compartments, the
computer updates the amount of no-decompression time (NDT) you
have left. As you ascend to shallower depths, the computer credits
you with more allowable NDT; if you go deeper, it reduces the NDT
available.
DIVING RESPONSIBLY
Figure 1
Rectangular Profile
Figure 2
Multi-Level Profile
FEATURES OF THE M2+
THE COMPUTER SCREEN
The M2+ has a large liquid crystal display (LCD) and features large
numbers and graphics. The screen is luminous for easy reading
during low light dives, including night dives and cave dives.
The illustration on the opposite page calls out each display number
or icon and provides a brief description for each one.
THE ELECTRICAL CONTACTS
All surface operations and mode changes are made by the use of four
electrical contacts placed around the M2+'s screen. These contacts
are identified as A, B, C and D (see figure below). As a rule, contact
A is always touched in conjunction with one of the other three
contacts. After entering different modes, such as Memory Mode or
Pre-Dive Planning Mode, contact B always decreases a value, and
contact C always increases a value (always in combination with A).
To make contact, simply moisten your fingertips and touch the
appropriate pair of contacts at the same time. Release the contact as
soon as the operation has been activated, usually no more than one
second.
AUTOMATIC ACTIVATION
The M2+ automatically activates and starts working as soon as it is
submerged in water. This means you can enter the water and start
diving without turning on the computer first.
Occasionally, when diving in fresh water, there is not enough
electrical conductivty in the water to complete the circuit between
contacts. If this is the case, the M2+ will activate using a secondary
pressure switch. Therefore, there may be slight delay between
entering the water and the computer going into Dive Mode.
M2+ DISPLAY AND CONTACT LETTER
DESIGNATIONS