Stand alone secondary computer use

[rddvet]

@rddvet my switch points are the same. Much easier to have the standalone "low" be your "dive" setpoint and "high" as my deco setpoint

It seems to make the most sense to me, but when I talked to Shearwater they felt that was far from the norm. He was saying that the way the auto setpoint switch is set up is for the Lo to be your surface p02 (so like a 0.7) and the high to be bottom portion of the dive. I don't understand how it would calculate your deco once at your stops since it would be using the wrong setpoint.

I think it's something that may come up in their next firmware discussions.

 

[doctormike]

And there is no way to switch it to "Standalone mode" where it ignores all sensor input and lets you tell it your SP. So, the deco calculations are going to be wrong. But, if I had a standalone computer, it would be correct because I would flying the unit manually, maintaining a SP that matches what the SA computer thinks..

Well, I don't think that you can bypass voting logic and specify one sensor to automatically drive your deco, but you can just fly it in CCR mode with Internal Setpoints. That tells it to ignore input from the CCR and you just enter whatever PO2 you are maintaining manually. No difference between doing that with a NERD, the Controller or the SA, AFIK....

 

[stuartv]

Well, I don't think that you can bypass voting logic and specify one sensor to automatically drive your deco, but you can just fly it in CCR mode with Internal Setpoints. That tells it to ignore input from the CCR and you just enter whatever PO2 you are maintaining manually. No difference between doing that with a NERD, the Controller or the SA, AFIK....

I did not know that. I'll have to look for that in the menus.

Are you saying you can switch a controller from external sensors to Internal Setpoints DURING a dive? That would be the requirement in the particular scenario I brought up. And if you do that, can you still have it display the actual pO2 readings from the external sensors? You'd need that in order to fly it manually.

 

[stuartv]

@stuartv and @doctormike on the NERD thing, if you have a BOV, why would you ditch the loop? If I had a pair of Shearwaters on the rig though, I wouldn't have a standalone computer. No point.

@rddvet my switch points are the same. Much easier to have the standalone "low" be your "dive" setpoint and "high" as my deco setpoint

I don't have a BOV. But, you raise a good point. If you do have a BOV, then you would have much less concern with using a NERD.

 

[doctormike]

I did not know that. I'll have to look for that in the menus.

Are you saying you can switch a controller from external sensors to Internal Setpoints DURING a dive? That would be the requirement in the particular scenario I brought up. And if you do that, can you still have it display the actual pO2 readings from the external sensors? You'd need that in order to fly it manually.

Pretty sure you can, but would have to confirm that. In your scenario, you would put one of your computers (controller or NERD) into internal setpoint and use that for deco. You would leave the other on external, and then fly manually using the reading on that computer for the one sensor you knew was working. Again, no real difference between a SA and a NERD.

Fairly aggressive! Fun scenario to think through (I love those exercises). In reality, I would probably just bail out and do the extra deco.

 

[rjack321]

I did not know that. I'll have to look for that in the menus.
Are you saying you can switch a controller from external sensors to Internal Setpoints DURING a dive? That would be the requirement in the particular scenario I brought up. And if you do that, can you still have it display the actual pO2 readings from the external sensors? You'd need that in order to fly it manually.

Pretty sure you can, but would have to confirm that. In your scenario, you would put one of your computers (controller or NERD) into internal setpoint and use that for deco. You would leave the other on external, and then fly manually using the reading on that computer for the one sensor you knew was working. Again, no real difference between a SA and a NERD.

Fairly aggressive! Fun scenario to think through (I love those exercises). In reality, I would probably just bail out and do the extra deco.

You cannot change the shearwater from ext to int. during a dive. That menu is locked out once you're underwater - for very good reason you dont want to be changing those settings by accident in duress.
Having a standalone fixed sp computer running sideby side with live deco on the same settings I never have more than a 2-3 min discrepancy even when my ppO2 hasn't really matched the standalone very well.​