O2 Cell Replacement Time....

[tbone1004]

@michael-fisch why bother with analog output? It allows legacy devices to read it, but what's the point? You have an digital-analog-digital conversion which allows all sorts of issues, especially with any electrical interference. Send the digital signal straight to the device that wants to read it. Infinitely more reliable than dealing with fischer cables, analog voltage outputs, etc etc. That would be a complete waste.

 

[michael-fisch]

@michael-fisch why bother with analog output? It allows legacy devices to read it, but what's the point? You have an digital-analog-digital conversion which allows all sorts of issues, especially with any electrical interference. Send the digital signal straight to the device that wants to read it. Infinitely more reliable than dealing with fischer cables, analog voltage outputs, etc etc. That would be a complete waste.

Since I already own 4 Shearwaters that are spread out among my analog XCCR, Flex and SF2 rebreathers, I'm not excited about switching everything out - especially not all at once. The potential customer base is using analog cells with DA converters in their computers and would probably not welcome a radical replacement of everything they are used to using.
Converting the solid state sensors output to analog signals through an interface with multiple DA circuits and more than one battery is an easy fix and would appeal to a larger quantity of RB owners.
Michael

 

[tbone1004]

@michael-fisch I understand wanting to use legacy products. That said one of my issues with the XCCR and Megalodon *though the Tiburon fixes this* is that they were using proprietary connectors. You can take the monitor from your SF2 and go put it on any divecan optima, revo, JJ, now ISC Tiburon, etc. and it will work on all of those rebreathers. Hell you can plug it in underwater and since the cal data is stored on the rebreather not the handset, you could have a dive planned that includes use of a deco breather or a bailout CCR and just plug the computer from your SF2 #1 over to SF2 #2 and continue on your merry way. THAT is some seriously cool stuff that @Bruce_Partridge and his team did there. That is 100% brilliant.

To do what you are wanting to do is frankly going to cost at least as much as a new canbus based computer because it definitely won't fit in the head of any of those rebreathers, especially with multiple batteries. By the time the cost of machining a pod to hold all that stuff inside of it is sorted out, you should have just bought a new handset that worked with it and called it a day instead of engineering a much less reliable and more complex design just to appeal to people who are afraid of change. The CPOD is almost $600 to do what you're asking it to do for a single cell. A new computer is $1500. By the time you put the rest of the stuff in you're going to be close to a grand, and that's PER rebreather. Spend $1500 for a new computer and cable that will handle it all and be done with it.

 

[Jeremy Williams]

** I don't know any more about the Shearwater DiveCAN products than anybody else. I just read what they put on the Internet. Beware of my wild speculation. **

When you say "Computer" I think of the handset. I wouldn't think it would need any hardware changes at all... The existing DiveCAN Petrels should be capable with a software upgrade. Support for the CO2 sensor in the XCCR was delivered in the v53 software release for the Petrel. That's the beauty of the DiveCAN system. You would need a new powered device on the DiveCAN bus to drive the SSO2 sensor and new software for the existing SOLO/OBOE boards to know how to talk to the new device and to use the ppO2 messages it will be sending back.

The problem is... where do you put it!

The reason the DiveCAN rebreathers can store all the calibration in the head is that all of that processing is done in the head too. The SOLO board reads the data from the sensors and fires the solenoid without the direct participation of the handset. The more I think about it, I bet it's going to be hard to retrofit. The wiring to the existing sensors almost certainly terminates on an ADC somewhere buried in the head. That's surely why the Se7ens need to go back to the factory to put the SSO2 sensor in the head. Does any rebreather have a DiveCAN interface inside the loop? Would you put a battery of some sort inside the loop to power the SSO2 sensor?

I bet that's why you're only going to see support for this in some future iteration of the SOLO/OBOE boards in some next generation heads. But hey... the Petrel is probably the least of your worries.

 

[rjack321]

You guys are going to be talking about these hypothetical "retrofits" until these sensors die from old age or lack of use. lol

 

[tbone1004]

@Jeremy Williams they'd all have to go back to the factory in one way or another. Something like the Liberty may not have to since it's all modular. The Tiburon, XCCR, and Revo may not have to, but everything else would.

@rjack321 blissful optimism?

 

[cathal]

I thought divers had thicker skin. Grow up. It's just a word and this isn't the beginners forum.

I have to wonder if you actually read what I wrote. Try it again.

If you pump your loop full of pure oxygen and immediately descend beyond 20', what do you call it? We can use your term I guess, whatever that is. But to me, it's stupid. Kinda like looking down the barrel of a gun to determine if it's loaded.

I guess I could have said, "you don't possess the common sense and intelligence necessary to dive a CCR" but "stupid" was less typing.

To paraphrase from another thread on another forum, Shaming in this manner by calling someone stupid WILL NOT improve diving safety, it just leads to the dive community being unable to provide and receive feedback which allows better learning and improved safety. It also leads to increased friction and hides much bigger systemic issues.

If someone flushes their loop at 6M with pure O2 and continues to descend the relevant discussion to have would be:
1. Who was their Instructor and training agency?
2. Was this taught as part of the course syllabus?
3. If the answer is yes then that agency needs to be contacted asap, if the answer is no then the diver needs to review their course syllabus with an instructor

These actions remedy the situation and educate both the diver and the dive community. Unfortunately shaming and labeling divers as being stupid does neither.

 

[jgttrey]

Jeebus. How about a reality check here?

I agree that it would not be productive to make fun of or insult an ACTUAL PERSON who came forward to ask a question or report a mistake. However, @Superlyte27 just made an observation about a hypothetical diver who can't be trusted to remember not to crash dive after having flushed his loop, noting that such a person probably shouldn't be diving CCR to begin with and we shouldn't build procedures around that type of diver.

If somebody posting in the basic forum got called a dummy for having made mistake, I'd agree. But, here the only threat to the "dive community being able to provide and receive feedback" is misplaced sensitivity that might cause our resident experts to roll their eyes and move on.

 

[Superlyte27]

"Stupid is as stupid does, that's what momma always said." -Forrest Gump

 

[GLOC]

I thought divers had thicker skin. Grow up. It's just a word and this isn't the beginners forum.

I have to wonder if you actually read what I wrote. Try it again.

If you pump your loop full of pure oxygen and immediately descend beyond 20', what do you call it? We can use your term I guess, whatever that is. But to me, it's stupid. Kinda like looking down the barrel of a gun to determine if it's loaded.

I guess I could have said, "you don't possess the common sense and intelligence necessary to dive a CCR" but "stupid" was less typing.

The human brain works very hard at being an effective but efficient prediction machine. However, we can only predict against what we have perceived (different to seeing, hearing, feeling) and then matching it against previous patterns which we have encountered. If this involves a level of uncertainty, we subconsciously trade-off benefits against losses/gains and execute the action. We then monitor that change to see if it matches our patterns and we carry on. However, we are subject to confirmation bias (if we think something is going to happen, we look for evidence to confirm that and once we find it, we are happy, even if that evidence is extremely tenuous).

Calling someone stupid does nothing to help the learning because it stops the conversation which starts with 'how did it make sense for you to do that?'. If we have experiences (mental models) which are different to the subject, then, of course, we have different predictions. Outcome bias changes those models too. If nothing bad happened when we did something 'stupid', then we have created a model that says it won't always go wrong. The more we validate that model by doing the same activity and nothing bad happening, the more we believe we are right. Hindsight bias also influences analysis. If we know the outcome, we can spot the salient cues in the activity as it leads to disaster. This is what sets apart an expert from a novice, but even experts make mistakes...

Aviation is as safe as it is because aircrew, engineers and ATC personnel know that they can talk about their failures, mistakes AND violations safe in the knowledge that learning will take place and blame will not be attributed (with the exception of willful negligence and sabotage). Diving has a very long way to go to remove the judgemental attitudes which reduce learning across the community. If you've never made a mistake and done something 'stupid' (in hindsight), you are lying. Everyone makes mistakes and breaks the rules because there are always competing goals in our life.

You might find this clip useful to watch.
More than happy to take this into another thread if you (Mods) want.

Regards

Gareth