The transmitter will read whichever tank it is attached to. That is straightforward and there is no question about that. The question is about what the computer will display when I switch gases to a tank without a transmitter. It is a totally different question.
I am diving in rec mode and that was stated clearly. The Perdix was purchased with a view towards taking the Tec courses since I am now going on at least one dive trip a month. Let's just say that I'm doing my bucket list. The max depth I have been to is 40M on a number of instances since July which is what I am certified for. I have also been on a number of deco dives with instructors since July. I have two trips with over 40 dives scheduled between now and November when the wreck dive is to take place, if it takes place. I was certified 30 years ago and the wreck dive is with industry professionals (an instructor turned dive equipment wholesaler and the resort owner both of whom were certified before I was since I was certified by the shop that they were then associated with at that time).
The question really was posed to help me understand how the Perdix is programmed. I have looked at the videos and glanced at the manual but have not found the answer.
So I think you have your answer now, right? If you switch the active gas, then "everything" will reflect that new gas... pO2, NDL or required deco etc.
Note also that when these computers are calculating, they assume you have the gases available, that you have "defined" and turned on. So a simple example of this... You define 21% and 99% as your available gases. As you accumulate nitrogen and the Perdix begins to show you required deco, it is doing the calculations based on the assumption that you are carrying that 99%. I only mention this because I've been caught on repetitive dives. I did a deeper dive, and used O2 for deco. I then did a shallower dive which would also required a bit of deco, but I hadn't bothered to take my O2. Realizing this mid dive, I turned off the O2 in my Petral and watched my deco obligation pretty much double... thankfully, it was a light obligation. This is one of the real benefits of the Shearwaters,,, They let you fix your errors on the fly.
Regarding your comments about your experience and the depth of the dive, I hope I didn't come across as being judgmental. I do air dives to 170'/180' frequently.
Note however that there is a VERY significant difference between 40M and 55M. Regardless of when you were certified, if you aren't used to doing dives to that depth, you are likely to "feel" it... I'm surprised that a dive op would endorse a dive to that depth on air, but then again, that might be the norm in that part of the world. Presumably it's a bit of a bounce dive as it doesn't seem like you are going to be properly rigged for a "serious" deep/deco dive with the bulk of the dive being shallower. As I said earlier, using 32% as a deco gas is almost pointless.
