Poseidon SE7EN User Manual
Appendix 3 Page 108
Oxygen sensor confidence
One of the most sophisticated features of the
Poseidon SE7EN is the automatic oxygen sensor
validation system, which monitors the reliability
of the oxygen sensors throughout the dive.
Through a series of algorithms, the system
assigns a confidence rating to current oxygen
sensor readings, based on several factors includ-
ing primary sensor validation, dynamic response
of sensors, and a comparison between primary
and secondary sensor values. If, for some
reason, the system loses confidence in the
oxygen sensors, then every few seconds an error
will be displayed momentarily on the Primary
Display where the PO
2
value is normally dis-
played – in a manner similar to how the PO
2
Setpoint is displayed. If there is no confidence in
the oxygen sensors, then “C0” is displayed.
Other levels of confidence based on various
factors include “C1”, “C2”, and “C3”. The last of
these (“C3”) is normal, and means the system
has high confidence in the sensors. The other
levels (“C0”, “C1” & “C2”) generate errors, and
will trigger appropriate alarms.
Figure 3-16.
Oxygen sensor confidence alerts: C0, C1, C2.
Mouthpiece position
The difference between “NC” (“no circuit”) and “UN” (“unknown”) depends on whether the
mouthpiece is reporting that neither closed-circuit nor open-circuit is currently established (“no
circuit”), or whether the mouthpiece is not reporting any position information at all (“unknown”).
In the former case, the problem is likely due to the mouthpiece switch being in the wrong
position, one or both of the magnets inside the mouthpiece being damaged or corrupted, or a
problem with the magnet sensors in the HUD. The latter case would arise if the HUD was
unable to communicate reliably with the SE7EN or report that the mouthpeice is in both open
and closed position at the same time. In any case, if the displayed value of the mouthpiece
position is not what it should be, first check the actual position of the mouthpiece, make sure
it is firmly and completely in one position or the other, and attempt to wiggle the HUD slightly.
Figure 3-17.
Closed Circuit mode.
Figure 3-18.
Open Circuit mode.
Directly to the right of the PO
2
value the mouthpeice position is communicated:
• “CC” (mouthpiece is in the Closed Circuit position)
• “OC” (mouthpiece is in the Open-Circuit position)
• “NC” (mouthpiece is not fully in either position), or “UN” (mouthpiece position is unknown).
Figure 3-19.
No Circuit mode.
Figure 3-20
. Mouthpiece position Unknown.
