Cheapest computer with liberal algorithm

[OctopusLover]

2 different Oceanic Pro Plus 3 unwarranted violations within 12 hours

5 divers, 2 Shearwater Perdix computers, A Pro Plus X, and 2 Pro Plus 3's. All diving identical profiles and Nitrox blends. All well within reg profiles, absolutely nothing froggy. My wife's Pro Plus 3 began flashing UP about 20 minutes into the third dive of the second day, max dept of 50...

scubaboard.com

Something (altitude sensor?) fails and the computer goes into its max conservative mode which assumes the dive is at altitude, you are using air for depth (even if you specify nitrox) and you are using 40% O2 for CNS toxicity.

altitude sensor and depth sensor are the same thing, a pressure sensor. If his depth readings were correct, I don't see how this could happen.

-- https://catb.org/jargon/html/B/bit-rot.html

I'm a software dev myself, I understand this as it applies to source code, but to a dive computer? Perhaps I lack imagination

 

[lowwall]

altitude sensor and depth sensor are the same thing, a pressure sensor. If his depth readings were correct, I don't see how this could happen.


I'm a software dev myself, I understand this as it applies to source code, but to a dive computer? Perhaps I lack imagination

Something failed. I was guessing that something triggered its max conservative mode. Without a circuit schematic and a copy of the code, I can't do anything other than guess.

 

[MarkA]

altitude sensor and depth sensor are the same thing, a pressure sensor. If his depth readings were correct, I don't see how this could happen.

As you say. It is a pressure sensor.

Say you are at sea level and air pressure is about 1,000mbar. Instead of measuring 1,000mbar the sensor thinks it is 700mbar (aprox 3000m) and an altitude dive. The dive computer will then assume the surface (0m) is 700mbar. Once The computer senses 1,700mbar it would display 10m. So if it is the zero of the sensor that is incorrect, it would still display the correct depth.

Not saying this is what happened, but it is a possibility.

My dive computer displays what it thinks ambient pressure is (ostc). My previous ones did not.

 

[lowwall]

As you say. It is a pressure sensor.

Say you are at sea level and air pressure is about 1,000mbar. Instead of measuring 1,000mbar the sensor thinks it is 700mbar (aprox 3000m) and an altitude dive. The dive computer will then assume the surface (0m) is 700mbar. Once The computer senses 1,700mbar it would display 10m. So if it is the zero of the sensor that is incorrect, it would still display the correct depth.

Not saying this is what happened, but it is a possibilit.

My dive computer displays what it thinks ambient pressure is. My previous ones did not.

Good point. It did not display ambient pressure. Neither did it have any way to indicate that it thought it was an altitude dive.

If the pressure sensor was reading slightly low (say 10%), it would trigger the altitude compensation but I wouldn't have noticed the depth discrepancy. 50' and 55' look the same to me.