Split sensors or not (rEvo, 5 cells)?

[beldridg]

I'm not sure the best way to start a new thread, but....

During an interesting discussion cell rotation strategies and failures, I posted about an experience about a cell failure that was connected to a "monitor" on my system and then there was a reply about cell splitting:

Interesting post, thank you. I also dive a rEvo with petrel controller and recently changed from a nerd1 to a nerd2. The only difference is I use a splitter on cell 3 so both computers display 3 cells. I assume with 3 cells on the nerd2 it would behave like my petrel if I had a cell failure?

This is interesting to consider.

Assume you have a rEvo with 5 cells.

Three are wired into the controller (doesn't matter if it is a NERD or a Petrel) and two are wired into the secondary display (I'll use the term monitor).

Do you split one of the cells and wire it into both the controller and the monitor or do you keep them entirely separate (i.e., no splitter)?

I can see pros & cons of each and I'll post those thoughts at some point in the discussion, but I'm curious what others think?

- brett

 

[broncobowsher]

Dive that same setup. No splitters.

 

[KentB]

My nerd is my controller and I only have 2 on the petrel. No splitter

 

[lermontov]

I have 3 on petrel and 2 on nerd but I have a third molex (empty) on the nerd so if my comptroller does dies i can then take a cell and hook it up and i get my 3 cells on the nerd and drive it manually if i want to

 

[beldridg]

I have 3 on petrel and 2 on nerd but I have a third molex (empty) on the nerd so if my comptroller does dies i can then take a cell and hook it up and i get my 3 cells on the nerd and drive it manually if i want to

Yes, that it how it comes "standard" since the cable from the NERD is hardwired and has three molex connectors.

Some people split one of their cells and run it to that third cable on the NERD.

The real question is whether or not that is a good idea?

- brett

 

[broncobowsher]

I don't see a need for it. For me, I like the 3rd display for the AI. The mini display for T1 and T2.
Don't need the same information repeated again, no need for a splitter.

 

[Wibble]

I'd thought about splitting one cell between the controller and Nerd backup, to show three PPO2 readings on the Nerd. Talking to people about this a couple of points came up:

• The Revo has two completely separate electronics systems: controller and backup. A failure on one cannot affect the other as they're completely separate (forget flooding, etc.)
• By connecting a splitter, you're effectively connecting these two systems together. This could mean that a failure in that cell, or on the splitter cable, could render both systems useless.
• Having two cells on the backup (Nerd) encourages good monitoring practice; occasionally validating the PPO2 of the three cells on the controller.

Am happy I changed my mind. That third point I believe is very important.

Also the third position in the middle row on the Nerd is nicely replaced with the AI mini-pressure readings from the O2 and Dil.

 

[cathal]

• The Revo has two completely separate electronics systems: controller and backup. A failure on one cannot affect the other as they're completely separate (forget flooding, etc.)
• By connecting a splitter, you're effectively connecting these two systems together. This could mean that a failure in that cell, or on the splitter cable, could render both systems useless.

These points go to the nub of what you are proposing. By sharing cell 3 you are connecting the two electronic monitoring systems together. As it’s such an important factor, why not email rEvo to get the manufacturers view on what you are proposing, from a systems failure perspective? Peace of mind at least.

 

[broncobowsher]

I know people who slip a 6th cell into the center of the tray.

Another reason for not running a splitter, you have to mentally acknowledge that you are seeing one piece of data twice. If that data is bad you have to mentally process that you are looking at a single bit of bad data displayed across multiple displays. But that only applies for a single sensor which makes it even more confusing because you have to remember which on cell on each display is the shared data.

 

[Big-swede]

If only there was a way to run a better system with only 2 sensors...

Just kidding, I agree that it has some negative points to connect the two systems but I don't think it gives a lot of redundancy two only use 2 cells, not much more then 1 any way.