hi Mudley,.mudley wrote: ↑Sun Sep 22, 2019 6:20 pmHi Jean,
I have a new hottub and want to add it to my home automation system.
I've got a similar spa (also Balboa, https://www.tubs.fr/balboa-gs510dz-cont ... -2306.html).
The control system has 2 free rj45 ports (probably for extra touch panels).
So I want to do the same as you did, but still investigating about the what and how.
I do have enough it knowledge, but a huge lack of electrotechnical background.
Do you know how I can find out if my control system also needs to have the 500 ohm resistors (or more, or less ohm resistors).
I want to hook it up to a RPi, but for that to work, I have to add an 5v relay to it right?
First thing to do is to find out on the rj45 port(s) what does what. Some of the lines are used for buttons, and some are used for the display, but you'll have to find out which is which. Also there should be a +VCC and a ground line on these ports which you might be able to trace on the controller side. One way to do that is to measure the resistance between the rj45 lines and a known + or grnd point on the control board (with the board disconnected from power of course), I typically use the big capacitors that are used to filter the power supply, they're easy to identify and their polarity is well marked. Typically the - side of the capacitor is connected to the ground (which should be connected to one of the lines in the rj45 connector) and the + is typically connected to the +VCC which should also be connected to another line.
Once you have these two, you can start investigate some more.
One question though: your control panel seems to have lots of buttons. In the simplest setup, each button is connected to one of the lines, but it seems to me you have more buttons than you have lines, so this may not be the case. In your setup it's possible that there are two buttons associated to a given RJ45 line, one that pulls the line up to +VCC then other that pulls it to GRND, and the line is floating otherwise (some controllers do that).