Its on the dive options screen... Same screen you set your safety stop depth and (unfortunately) only in X10 mode. I'm quoting from the manual as I do not have this option on my VR3. I downloaded the manual from the vr3.co.uk website...
The Dive Options Screen
In surface mode the Dive Options (DVo) screen is accessible from the Home Screen,
(toggle through the mini-screens).
Underwater, the Dive Options (DVo) screen is accessed by a short push of both
switches when you are in the second dive screen. You get to the second dive screen
from the main dive screen via a long push on the right switch.
The screen allows the diver to get quick access to a number of useful controllable
features.
In this screen, a short push of both switches will move the highlight from one feature
to the next, a short push of either the left - or right + switch will change the setting. If
you do not have a particular feature enabled, the highlight will not land on it.
XFunc
Change XFunc to correspond to the type of sensor connected to the I/O port:
i. OFF = no sensor connected. When no sensors are connected XFunc should
be set to OFF to avoid connector damage.
ii. ii. XO2 = External PO2 sensor (analyzer or rebreather) connected.
XDec
This feature is enabled when you purchase one of our rebreather linking cables and
the relevant software to allow you to track real time decompression via an external
oxygen cell. In closed circuit mode the XDec setting controls which PO2 figure is
used in the decompression and tissue updating calculations. (In semi closed mode the
PO2 is reported as an FO2).
To summarise, when XDec = ON the reading from the external sensor is used.
When XDec = OFF the selected gas and internal setpoint are used.
VR Technology Limited
VR3 Dive Computer Operations Manual 2008 rev 1
13
BG (Big Graphics)
(This is only available with the VR3 in X10 mode.)
When you buy the PIN to activate Gas Calculator mode in your VR (item UG 15) you
also get the PIN for Big Graphics Mode free of charge. This enables you to double the
size of the depth and time digits in the Dive Screen with the VR3 in X10 mode only.
Note that CNS% and Time to Surface (TTS) information will not appear on the Dive
Screen while Big Graphics Mode is ON. Your No Stop Time (NST) remains visible,
as do your decompression ceiling and time at stop if you are carrying out a
decompression dive.
Light
Switch between three screen backlight modes
Tm............... Light on for 10 seconds at the surface or underwater
On................ Light always on at the surface and underwater
DOn............. Light off at the surface, light on underwater
Stops
Switch between 3 optional final decompression stop depths, 3m, 4.5m and 6m.
