A closer look at Vision

Tino de Rijk · 29th December 2006, 13:20

A closer Look at Vision

Tino de Rijk, The Netherlands, December 2006

Introduction

In November 2006 an experienced Inspiration diver reported a strange incident: during a dive in the Red Sea, his CO2 sensor TempStik readings suddenly flatlined, and his PO2 readings were frozen (as in: not changing anymore, stuck to the same value) on the wrist display.

It triggered a lot of E-mails with people wondering if the Inspiration would still be life-supporting in this stage. It occurred to me that a lot of reasoning about this was by Vision and non-Vision divers that still reason with the “old” Inspiration Classic (the one with the dual handsets) in mind.
In a Classic, a frozen display typically indicates that that controller isn’t properly functioning anymore. However, the total hardware setup of the Vision is so radically different from the Classic that these comparisons have little value anymore.

Having translated the Vision manuals into Dutch, I know that not all text about the inner workings of the Vision, and especially of the workings in case of component failure(s), is nicely put together in one place. So I compiled a set of questions, fired them off to the as usual friendly and helpfull people at Ambient Pressure Diving, and as usual I got a very extensive reply back pronto. So consider this text verified by the factory.

The rest of this memo is split in two parts:

a closer look at Vision: which component of Vision controls which function?
A “what if component x fails?” section, digging into what you might see during a failure, and what it could mean to you in terms of appropriate reactions.

Here we go!

A closer look at Vision: which component controls which function?

Vision component sum-up

The vision Electronics consist of three controllers, three displays, two batteries, an intelligent bus, a buzzer and an optional TempStik scrubber monitor:

1 computer in the wrist display unit, further referred to by me as the WDC (Wrist Display Controller);
2 redundant, but independent controllers in the lid of the scrubber with as main function oxygen level (PO2) control, referred to by me further on as SPC (SetPoint Controllers);
A serial databus that connects the WDC with the SPC’s and also houses a real-time clock (RTC) to supply the logbook functions of the Vision with the correct date & time.
It also contains a “hub” to provide electrical and functional isolation in the event of a failure of any one component hooked up to the databus;
Physically, the databus bus is represented by the electric cables running through the rubber medium-pressure hose between scrubberlid and WDC;
1 LCD wrist display, built into the WDC that shows the detailed status of the system;
2 redundant, but independent HUD displays, comprising a green and red light each, placed on top of the mouthpiece. It is important to note that the actual LED’s themselves are located in the scrubber lid, near the SPC’s, and the light is transported to the end of the HUD through a fiber-optic cable. This was done to avoid having to use a thin, vulnerable electric cable all the way to the mouthpiece and having to use relatively big LED’s there, as in most other HUD designs.
2 batteries (non-rechargeable CRP2 type Lithium), placed next to the SPC’s in the scrubber lid, in a water-resistant housing.
A “buzzer on a stalk”, located to the left ear, and driven by the SPC’s.
An optional TempStik, that measure the progressing warmth front that travels through the scrubber bed as the Sofnolime progressively gets spent, causing an exothermic reaction in the process. The measurement is done by a number of serially placed temperature sensors in the central pole of the scrubber container.

Functions per component

So, after this sum-up, let’s look at which component does what. This is VERY important in order to determine later on which functionality you may loose if a given component fails on you!

- Contrary to popular believe, and probably also driven by wrong comparisons between the Classic and the Vision, the WDC is in my view NOT the most important component of Vision. Yes, it gives you a detailed view of it’s status, and it lets you control all settings of the system, but it also does NOT do some important things:

it does NOT control the PO2 (setpoint maintenance),
it does NOT control the solenoid,
it does NOT control the two HUD’s (that is done by the SPC’s: each SPC runs its own HUD),
it does NOT control the buzzer, and
it does NOT control power management (switching between batteries, and combining them, in case of an empty battery)

- The WDC does some other important things though:

It contains the pressure transducer (digital pressure gauge) for depth measurement. It is located in the bottom of the WDC, shielded by the bottom plate that holds the straps;
It executes all CCR and OC decompression calculation functions;
It does control the value of the two setpoints, and (auto-)switching between them;
It contains the round-robin (FIFO) log memory for alter readout of dive profile and warnings.

- So, loosing the WDC does NOT mean losing a reliable setpoint maintenance, or even the ability to verify that, as the HUD’s are driven directly by the SPC’s (each SPC has its own HUD). However, you would loose your decompression information, but more on that later.
Realize also that for proper CCR deco calculations, you only need three external inputs:

depth (coming from the built-in pressure transducer in the WDC),
time (coming from its internal oscillator in the WDC; see below) and
PO2 (supplied to the WDC by the SPC’s, its datastream transported to the WDC over the databus).

For OC calculations you even only need depth and time and the gas mix, not more; the rest is algorithm, executed by the program code in the WDC.

The RTC is located near the SPC’s on the databus; it is only used for time-stamping logbook entries (dive profile, warnings and errors). However, each controller (WDC and the 2 SPC’s) maintains its own internal tick count, based on its own built-in oscillators.

The solenoid is controlled by both SPC’s, also different from the Classic. The Master SPC controls the setpoint and thus the solenoid if everything is normal and o.k., but the solenoid is linked through a so-called “wired-or” configuration to both SPC’s. The secondary SPC (slave is actually not a good word anymore in Vision terms) also independently monitors the PO2 (through its own cell readings), and starts acting intervening when the PO2 falls below 80% of the current target setpoint. This happens without the need to switch from master to slave, as on the Classic, and acts as a “catch all” safety-net function.

A similar thing happens for power management. Normally the primary (“master”) SPC will perform battery management (switching to the secondary battery in case of battery-low, and later combining the two parallel when both are low). But also here, the secondary SPC can intervene if the active “master” SPC is not able to perform this function.

The SPC’s also contain the calibration correction factors, established during calibration of the unit. As in the Classic, each SPC contains and retains its own set of correction factors: 3, one for each cell.

Now, let’s look closer at the WDC:
As mentioned before, it contains the log memory, on non-volatile, round-robin, FIFO memory. This means a “dead” battery will not cause a loss of logbook info, as unfortunately many diving computers do.

The WDC receives the following data from the SPC’s over the databus:

Real-time PO2 info, supplied by the SPC’s;
Battery status info, also supplied by the SPC’s;
TempStik data, received directly from the TempStik (no SPC “interference” here);
PO2- and cell-related warnings and errors, as generated by the SPC’s.

The WDC on its turn can send commands to the SPC’s:

Power up/down;
Do calibration;
Change setpoint. The SPC however does a validation of the new setpoint request.
It will e.g. refuse a new setpoint of 2.0 if for some error reason the WDC would send that.
Switch setpoint. This is effectively a setpoint change, initiated by the WDC, either on instruction of the user (long press of center button), or by the auto-switch function, driven by passing a certain depth. Remember that only the WDC ‘knows” the current depth!
Warnings and errors that are not PO2-related, e.g. decompression errors and warnings. They are sent from the WDC to the SPC with the sole purpose of showing them on the HUD’s and the buzzer, as both of these are controlled by the SPC’s.

The WDC cannot trigger the buzzer by itself: it needs a SPC to do that. The same applies to displaying errors and warnings on the HUD’s.

“What if component x fails?”

In this paragraph I will not go into what bail-out or other actions are appropriate if a component fails. That is up to the instruction agencies or your smart self to decide. E.g.: do you stay on the loop or not in case of a WDC or databus failure? In my PERSONAL view it is totally justified to do that, flying it on the HUD’s, but at the same time for sake of “peace of mind” I could very well defend going OC, as you have less info to draw on.

So by now it should be clear that e.g. auto-switching, or in fact any change in setpoint, will not occur anymore if the WDC malfunctions, or the databus link is lost. The latter was the most likely reason of the failure reported by the diver in the introduction, by the way.

If the databus link is lost (e.g. broken cable in the wiring loom between WDC and SPC’s, the following will occur:

The WDC will not show the proper PO2 numbers anymore. In the current version of the Vision firmware (V02.01.02) This shows up as a seemingly frozen PO2 display. However, APD promised me that in a near future version of the software (likely already in the next V02.01.03 version), the WDC will show asterisks (*.**) instead of the last received value when it does not receive proper PO2 data anymore. This will make it much easier to spot, even though static numbers should be a clear tell-tale of trouble for a CCR diver.
I stress the wording “frozen PO2 display” instead of “frozen computer”, as the other display functions (e.g. decompression, time, depth) continue showing valid data if only the databus fails;
The TempStik data will not show anymore, its black and white temperature progression bar replaced by dashes. This was also reported by the same diver;
Depth and time continue running, and are logged correctly in memory, as can be clearly seen in the logbook download file supplied by the affected diver on Internet. This includes things like ascent alarms till the very end of the dive, but at the same time will not contain proper PO2 data and/or PO2 related warnings and errors anymore.
Switching off is not possible anymore: the WDC cannot instruct the SPC’s to do this anymore.
Setpoint changing (either auto or manual) cannot be performed anymore. The most recent setpoint is maintained;
Setpoint maintenance however can be verified: a quick squirt on the manual O2 button, followed by a diluent flush, will run the HUD’s and buzzer through all main functions: rapid blinking and red due to setpoint higher that 1.6, followed by green, followed by slow blinking and red due to setpoint low, followed by green again when the SPC instructs the solenoid to open till the setpoint is o.k. again. This is a quick set of actions that can easily be performed.
Your CCR deco-calculations are however not linked to the actual PO2 value in the loop anymore: they will feed on the last received frozen PO2 values or, in the next version of the firmware, the current static setpoint value.
You could elect to switch the computer to OC-mode, even if you decide to stay on the loop. As this is in most cases safe, because OC decostop-times are typically longer, this would be a justified action. However, in the before mentioned upcoming firmware update (V02.01.03), the unit will default to the current setpoint value and so will act as if it is an unlinked deco computer and as such can safely be used. Very much like a Buddy Nexus or a VR3 without 4th cell!
Similarly, in the current version of the firmware (V02.01.02), if the frozen PO2 values are close to the setpoint then the value used is again sufficiently close to act as an unlinked deco computer, and is again safe to use. Proper dive planning should however ensure you always have tables as backup.

Let’s run through some other, more simple error scenario’s, to be sure we’re all on the same page by now:

if a SPC fails, its HUD will go off (its lights will go off), and its values will not show anymore on the WDC. (currently shown as all zeros, newer version will show as asterisks)
If you suspect a SPC of being frozen, do the “squirt with O2 + dil flush” test as described above. It that case the WDC can instruct the secondary SPC to take over. This SPC already has the above described “catch all” function that kicks in if the PO2 drops to 80% of the current setpoint.
If the WDC or databus fails, deco- and ascent-related errors will not pop up on the HUD’s, or trigger the buzzer.
If the WDC or databus fails, and you do not feel comfortable flying it solely on the HUD’s (which give less info than the WDC screen), you can still elect to do the ascent on OC, taking extra care when using hypoxic mixes, but go back to CC at 6 meters, effectively running it as an oxygen rebreather. You can then use the HUD as indication you should inject O2 again, as you likely strive to maintain a PO2 of 1.5 or 1.6, which will cause the HUD the blink fast. If the PO2 drops to 1.3 (assuming the last selected setpoint was 1.3), the HUD’s will go steady green, indication you to inject O2 again. Nice feature!
If only the databus link fails, that will show up as frozen or asterisk PO2 data and dashes in the TempStik data (if fitted), but depth and time will still run. Check it, to isolate the error. It also means the WDC is still usable as an unlinked multi-gas constant PO2 and OC computer, as described above. Or at the very least as depthgauge + timer.
If the last selected setpoint was 1.3, and the WDC or databus fails, the unit will NOT switch back to low setpoint at 3 meters of depth. So: stay deeper than 3 meters to avoid wasting O2. Realize also that, contrary to the Classic, the Vision will keep the solenoid continuously open if the setpoint is too low; the classic does this in 17-second intervals, followed by 6 seconds “rest”.
Once you get to the surface, do NOT close the O2 valves: in the stress of the situation (after all, you experienced an annoying failure), you might keep the CC mouthpiece in and get hypoxic. Better to loose all of your O2 slowly than go hypoxic! Better still: go to OC once on the surface. Once on the boat, unit taken off, close the O2 supply. You have to, as you will also not be able to switch the system off, as this is done by the WDC instructing the SPC’s…. you’ll have to remove the batteries.

That’s all. I hope this contributes to a better understanding of the Vision electronics, and effects of possible failure modes.

Ciao,

Tino.

PCDiver · 29th December 2006, 14:03

Great post Tino

decoweenie · 29th December 2006, 14:40

Didn't have time to read thru it in detail, but good post, Tino.

Have some green!

DaveB · 29th December 2006, 14:41

Quote: (Originally Posted by PCDiver)

Great post Tino

Seconded - thanks very much.

**jepuskar** · 29th December 2006, 15:00

Hi Tino,

I have an email from APD that states the power for both LEDs comes from its own battery and not the battery of either controller.

I also asked for a block diagram of the electronics as I think that would help answer several questions. Was told it was something they should work on.

J

**nigelh** · 29th December 2006, 16:07

Quote: (Originally Posted by Tino de Rijk)

That’s all. I hope this contributes to a better understanding of the Vision electronics, and effects of possible failure modes.

Tino,
Thank you for doing all the spadework to get that description.
I was wondering what was actually happening about it.

***caveseeker7*** · 29th December 2006, 18:35

Excellent effort, Tino, and much appreciated.

A well deserved blob from me.

**Gill Envy** · 29th December 2006, 19:23

have a blob! wow, a bunch of info i've never seen in the manual...maybe i should read it again but either way, this is great stuff to add to the debates about weather the evo/inspo vision really has adequate redundancy. Curious to see what comes of this.

***Louby Lou*** · 29th December 2006, 20:12

Tino

Excellent article - I've added it into the library and featured it on the front page. Hope this is ok.

The library software is being upgraded at the moment so if there are any problems give me a shout.

Cheers

Lou
RBW Admin

**jepuskar** · 29th December 2006, 20:47

Features like what Tino found out should be readily available. APD has to have something internally that lists all the fault conditions and how the controllers should act or not act. I did ask about a block diagram of the electronics, as stated above, but a matrix listing conditions and actions would be most helpful.

Users could use this to compare to their actual experiences and then could be in a better position to contact SDS or APD with their issues or an explanation. If the majority of rebreather divers are geeks, techies, gadget *****s, engineers, and whatever else...this kind of detail will be helpful.

If not included in the manual, make it an optional download or something.

Yeah, I know....

29th December 2006, 13:20	#1 (permalink)
Tino de Rijk Old, maybe one day wise Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Evolution Join Date: Mar 2006 Location: Amsterdam Posts: 372	A closer look at Vision A closer Look at Vision Tino de Rijk, The Netherlands, December 2006 Introduction In November 2006 an experienced Inspiration diver reported a strange incident: during a dive in the Red Sea, his CO2 sensor TempStik readings suddenly flatlined, and his PO2 readings were frozen (as in: not changing anymore, stuck to the same value) on the wrist display. It triggered a lot of E-mails with people wondering if the Inspiration would still be life-supporting in this stage. It occurred to me that a lot of reasoning about this was by Vision and non-Vision divers that still reason with the “old” Inspiration Classic (the one with the dual handsets) in mind. In a Classic, a frozen display typically indicates that that controller isn’t properly functioning anymore. However, the total hardware setup of the Vision is so radically different from the Classic that these comparisons have little value anymore. Having translated the Vision manuals into Dutch, I know that not all text about the inner workings of the Vision, and especially of the workings in case of component failure(s), is nicely put together in one place. So I compiled a set of questions, fired them off to the as usual friendly and helpfull people at Ambient Pressure Diving, and as usual I got a very extensive reply back pronto. So consider this text verified by the factory. The rest of this memo is split in two parts: a closer look at Vision: which component of Vision controls which function? A “what if component x fails?” section, digging into what you might see during a failure, and what it could mean to you in terms of appropriate reactions. Here we go! A closer look at Vision: which component controls which function? Vision component sum-up The vision Electronics consist of three controllers, three displays, two batteries, an intelligent bus, a buzzer and an optional TempStik scrubber monitor: 1 computer in the wrist display unit, further referred to by me as the WDC (Wrist Display Controller); 2 redundant, but independent controllers in the lid of the scrubber with as main function oxygen level (PO2) control, referred to by me further on as SPC (SetPoint Controllers); A serial databus that connects the WDC with the SPC’s and also houses a real-time clock (RTC) to supply the logbook functions of the Vision with the correct date & time. It also contains a “hub” to provide electrical and functional isolation in the event of a failure of any one component hooked up to the databus; Physically, the databus bus is represented by the electric cables running through the rubber medium-pressure hose between scrubberlid and WDC; 1 LCD wrist display, built into the WDC that shows the detailed status of the system; 2 redundant, but independent HUD displays, comprising a green and red light each, placed on top of the mouthpiece. It is important to note that the actual LED’s themselves are located in the scrubber lid, near the SPC’s, and the light is transported to the end of the HUD through a fiber-optic cable. This was done to avoid having to use a thin, vulnerable electric cable all the way to the mouthpiece and having to use relatively big LED’s there, as in most other HUD designs. 2 batteries (non-rechargeable CRP2 type Lithium), placed next to the SPC’s in the scrubber lid, in a water-resistant housing. A “buzzer on a stalk”, located to the left ear, and driven by the SPC’s. An optional TempStik, that measure the progressing warmth front that travels through the scrubber bed as the Sofnolime progressively gets spent, causing an exothermic reaction in the process. The measurement is done by a number of serially placed temperature sensors in the central pole of the scrubber container. Functions per component So, after this sum-up, let’s look at which component does what. This is VERY important in order to determine later on which functionality you may loose if a given component fails on you! - Contrary to popular believe, and probably also driven by wrong comparisons between the Classic and the Vision, the WDC is in my view NOT the most important component of Vision. Yes, it gives you a detailed view of it’s status, and it lets you control all settings of the system, but it also does NOT do some important things: it does NOT control the PO2 (setpoint maintenance), it does NOT control the solenoid, it does NOT control the two HUD’s (that is done by the SPC’s: each SPC runs its own HUD), it does NOT control the buzzer, and it does NOT control power management (switching between batteries, and combining them, in case of an empty battery) - The WDC does some other important things though: It contains the pressure transducer (digital pressure gauge) for depth measurement. It is located in the bottom of the WDC, shielded by the bottom plate that holds the straps; It executes all CCR and OC decompression calculation functions; It does control the value of the two setpoints, and (auto-)switching between them; It contains the round-robin (FIFO) log memory for alter readout of dive profile and warnings. - So, loosing the WDC does NOT mean losing a reliable setpoint maintenance, or even the ability to verify that, as the HUD’s are driven directly by the SPC’s (each SPC has its own HUD). However, you would loose your decompression information, but more on that later. Realize also that for proper CCR deco calculations, you only need three external inputs: depth (coming from the built-in pressure transducer in the WDC), time (coming from its internal oscillator in the WDC; see below) and PO2 (supplied to the WDC by the SPC’s, its datastream transported to the WDC over the databus). For OC calculations you even only need depth and time and the gas mix, not more; the rest is algorithm, executed by the program code in the WDC. The RTC is located near the SPC’s on the databus; it is only used for time-stamping logbook entries (dive profile, warnings and errors). However, each controller (WDC and the 2 SPC’s) maintains its own internal tick count, based on its own built-in oscillators. The solenoid is controlled by both SPC’s, also different from the Classic. The Master SPC controls the setpoint and thus the solenoid if everything is normal and o.k., but the solenoid is linked through a so-called “wired-or” configuration to both SPC’s. The secondary SPC (slave is actually not a good word anymore in Vision terms) also independently monitors the PO2 (through its own cell readings), and starts acting intervening when the PO2 falls below 80% of the current target setpoint. This happens without the need to switch from master to slave, as on the Classic, and acts as a “catch all” safety-net function. A similar thing happens for power management. Normally the primary (“master”) SPC will perform battery management (switching to the secondary battery in case of battery-low, and later combining the two parallel when both are low). But also here, the secondary SPC can intervene if the active “master” SPC is not able to perform this function. The SPC’s also contain the calibration correction factors, established during calibration of the unit. As in the Classic, each SPC contains and retains its own set of correction factors: 3, one for each cell. Now, let’s look closer at the WDC: As mentioned before, it contains the log memory, on non-volatile, round-robin, FIFO memory. This means a “dead” battery will not cause a loss of logbook info, as unfortunately many diving computers do. The WDC receives the following data from the SPC’s over the databus: Real-time PO2 info, supplied by the SPC’s; Battery status info, also supplied by the SPC’s; TempStik data, received directly from the TempStik (no SPC “interference” here); PO2- and cell-related warnings and errors, as generated by the SPC’s. The WDC on its turn can send commands to the SPC’s: Power up/down; Do calibration; Change setpoint. The SPC however does a validation of the new setpoint request. It will e.g. refuse a new setpoint of 2.0 if for some error reason the WDC would send that. Switch setpoint. This is effectively a setpoint change, initiated by the WDC, either on instruction of the user (long press of center button), or by the auto-switch function, driven by passing a certain depth. Remember that only the WDC ‘knows” the current depth! Warnings and errors that are not PO2-related, e.g. decompression errors and warnings. They are sent from the WDC to the SPC with the sole purpose of showing them on the HUD’s and the buzzer, as both of these are controlled by the SPC’s. The WDC cannot trigger the buzzer by itself: it needs a SPC to do that. The same applies to displaying errors and warnings on the HUD’s. “What if component x fails?” In this paragraph I will not go into what bail-out or other actions are appropriate if a component fails. That is up to the instruction agencies or your smart self to decide. E.g.: do you stay on the loop or not in case of a WDC or databus failure? In my PERSONAL view it is totally justified to do that, flying it on the HUD’s, but at the same time for sake of “peace of mind” I could very well defend going OC, as you have less info to draw on. So by now it should be clear that e.g. auto-switching, or in fact any change in setpoint, will not occur anymore if the WDC malfunctions, or the databus link is lost. The latter was the most likely reason of the failure reported by the diver in the introduction, by the way. If the databus link is lost (e.g. broken cable in the wiring loom between WDC and SPC’s, the following will occur: The WDC will not show the proper PO2 numbers anymore. In the current version of the Vision firmware (V02.01.02) This shows up as a seemingly frozen PO2 display. However, APD promised me that in a near future version of the software (likely already in the next V02.01.03 version), the WDC will show asterisks (.) instead of the last received value when it does not receive proper PO2 data anymore. This will make it much easier to spot, even though static numbers should be a clear tell-tale of trouble for a CCR diver. I stress the wording “frozen PO2 display” instead of “frozen computer”, as the other display functions (e.g. decompression, time, depth) continue showing valid data if only the databus fails;* The TempStik data will not show anymore, its black and white temperature progression bar replaced by dashes. This was also reported by the same diver; Depth and time continue running, and are logged correctly in memory, as can be clearly seen in the logbook download file supplied by the affected diver on Internet. This includes things like ascent alarms till the very end of the dive, but at the same time will not contain proper PO2 data and/or PO2 related warnings and errors anymore. Switching off is not possible anymore: the WDC cannot instruct the SPC’s to do this anymore. Setpoint changing (either auto or manual) cannot be performed anymore. The most recent setpoint is maintained; Setpoint maintenance however can be verified: a quick squirt on the manual O2 button, followed by a diluent flush, will run the HUD’s and buzzer through all main functions: rapid blinking and red due to setpoint higher that 1.6, followed by green, followed by slow blinking and red due to setpoint low, followed by green again when the SPC instructs the solenoid to open till the setpoint is o.k. again. This is a quick set of actions that can easily be performed. Your CCR deco-calculations are however not linked to the actual PO2 value in the loop anymore: they will feed on the last received frozen PO2 values or, in the next version of the firmware, the current static setpoint value. You could elect to switch the computer to OC-mode, even if you decide to stay on the loop. As this is in most cases safe, because OC decostop-times are typically longer, this would be a justified action. However, in the before mentioned upcoming firmware update (V02.01.03), the unit will default to the current setpoint value and so will act as if it is an unlinked deco computer and as such can safely be used. Very much like a Buddy Nexus or a VR3 without 4th cell! Similarly, in the current version of the firmware (V02.01.02), if the frozen PO2 values are close to the setpoint then the value used is again sufficiently close to act as an unlinked deco computer, and is again safe to use. Proper dive planning should however ensure you always have tables as backup. Let’s run through some other, more simple error scenario’s, to be sure we’re all on the same page by now: if a SPC fails, its HUD will go off (its lights will go off), and its values will not show anymore on the WDC. (currently shown as all zeros, newer version will show as asterisks) If you suspect a SPC of being frozen, do the “squirt with O2 + dil flush” test as described above. It that case the WDC can instruct the secondary SPC to take over. This SPC already has the above described “catch all” function that kicks in if the PO2 drops to 80% of the current setpoint. If the WDC or databus fails, deco- and ascent-related errors will not pop up on the HUD’s, or trigger the buzzer. If the WDC or databus fails, and you do not feel comfortable flying it solely on the HUD’s (which give less info than the WDC screen), you can still elect to do the ascent on OC, taking extra care when using hypoxic mixes, but go back to CC at 6 meters, effectively running it as an oxygen rebreather. You can then use the HUD as indication you should inject O2 again, as you likely strive to maintain a PO2 of 1.5 or 1.6, which will cause the HUD the blink fast. If the PO2 drops to 1.3 (assuming the last selected setpoint was 1.3), the HUD’s will go steady green, indication you to inject O2 again. Nice feature! If only the databus link fails, that will show up as frozen or asterisk PO2 data and dashes in the TempStik data (if fitted), but depth and time will still run. Check it, to isolate the error. It also means the WDC is still usable as an unlinked multi-gas constant PO2 and OC computer, as described above. Or at the very least as depthgauge + timer. If the last selected setpoint was 1.3, and the WDC or databus fails, the unit will NOT switch back to low setpoint at 3 meters of depth. So: stay deeper than 3 meters to avoid wasting O2. Realize also that, contrary to the Classic, the Vision will keep the solenoid continuously open if the setpoint is too low; the classic does this in 17-second intervals, followed by 6 seconds “rest”. Once you get to the surface, do NOT close the O2 valves: in the stress of the situation (after all, you experienced an annoying failure), you might keep the CC mouthpiece in and get hypoxic. Better to loose all of your O2 slowly than go hypoxic! Better still: go to OC once on the surface. Once on the boat, unit taken off, close the O2 supply. You have to, as you will also not be able to switch the system off, as this is done by the WDC instructing the SPC’s…. you’ll have to remove the batteries. That’s all. I hope this contributes to a better understanding of the Vision electronics, and effects of possible failure modes. Ciao, Tino.
(Offline)

29th December 2006, 14:03	#2 (permalink)
PCDiver Submerge Productions Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: Belgium Posts: 999	Re: A closer look at Vision Great post Tino
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29th December 2006, 14:40	#3 (permalink)
decoweenie Crash Test Dummy Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Cairo Posts: 5,487	Re: A closer look at Vision Didn't have time to read thru it in detail, but good post, Tino. Have some green! __________________ "...after a while you get bored offering advice to a bull that like to keep butting the fence with its head rather than walking through the open gate..." - Rebreather World PM
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29th December 2006, 14:41	#4 (permalink)
DaveB RBW Writer Current Rebreather/s: Evolution Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: Belper, Derbyshire, UK Posts: 89	Re: A closer look at Vision Quote: (Originally Posted by PCDiver) Great post Tino Seconded - thanks very much. __________________ David
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29th December 2006, 15:00	#5 (permalink)
jepuskar NA Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Aug 2005 Location: Chicago, IL Posts: 397	Re: A closer look at Vision Hi Tino, I have an email from APD that states the power for both LEDs comes from its own battery and not the battery of either controller. I also asked for a block diagram of the electronics as I think that would help answer several questions. Was told it was something they should work on. J
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29th December 2006, 16:07	#6 (permalink)
nigelh New member Current Rebreather/s: Inspiration Vision Other CCR Other Rebreather/s: Inspiration Classic Other CCR Join Date: Mar 2005 Location: Brighton, Sussex, UK Posts: 874	Re: A closer look at Vision Quote: (Originally Posted by Tino de Rijk) That’s all. I hope this contributes to a better understanding of the Vision electronics, and effects of possible failure modes. Tino, Thank you for doing all the spadework to get that description. I was wondering what was actually happening about it. __________________ nigelh
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29th December 2006, 18:35	#7 (permalink)
*caveseeker7* Who loves ya, baby Current Rebreather/s: Sport Kiss Other Rebreather/s: Prism Topaz Join Date: Jan 2005 Location: Too far from Neverland Posts: 5,535	Re: A closer look at Vision Excellent effort, Tino, and much appreciated. A well deserved blob from me. __________________ Cheers Stefan "Political Correctness is a doctrine, fostered by a delusional, illogical minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.!"
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29th December 2006, 19:23	#8 (permalink)
Gill Envy Shearwater Copis Divers Current Rebreather/s: Other CCR Other Rebreather/s: Evolution Other CCR Join Date: Nov 2005 Location: seattle Posts: 1,341	Re: A closer look at Vision have a blob! wow, a bunch of info i've never seen in the manual...maybe i should read it again but either way, this is great stuff to add to the debates about weather the evo/inspo vision really has adequate redundancy. Curious to see what comes of this. __________________ Gill Envy ...Because I wasn't born with gills! ><(°>><(°>><(°>><(°>><(°>><(°>><(°>><(°>
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29th December 2006, 20:12	#9 (permalink)
*Louby Lou* XLVI WC! Current Rebreather/s: Inspiration Vision Other Rebreather/s: Inspiration Classic Join Date: Feb 2005 Location: Roman Corinium! Posts: 1,040	Re: A closer look at Vision Tino Excellent article - I've added it into the library and featured it on the front page. Hope this is ok. The library software is being upgraded at the moment so if there are any problems give me a shout. Cheers Lou RBW Admin __________________ Miss Lou x Use of RBW is subject to the Rebreatherworld Terms and Conditions - Please read! Outlaw Divers - Sssh we're diving! You heff vays uff dealink vis zem, oh Miss RBW Admin! - Rob Davie Feb 06
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29th December 2006, 20:47	#10 (permalink)
jepuskar NA Current Rebreather/s: Not Bought Yet Other Rebreather/s: Not Bought Yet Join Date: Aug 2005 Location: Chicago, IL Posts: 397	Re: A closer look at Vision Features like what Tino found out should be readily available. APD has to have something internally that lists all the fault conditions and how the controllers should act or not act. I did ask about a block diagram of the electronics, as stated above, but a matrix listing conditions and actions would be most helpful. Users could use this to compare to their actual experiences and then could be in a better position to contact SDS or APD with their issues or an explanation. If the majority of rebreather divers are geeks, techies, gadget *****s, engineers, and whatever else...this kind of detail will be helpful. If not included in the manual, make it an optional download or something. Yeah, I know....
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