I am in the process of wiring the RS 485 port of my older Dometic SMX II Air Conditioning controller to my Cerbo GX and looking for the protocol used by Dometic. Anyone either reverse engineer this or get it through Dometic?
Hi David, that sounds like a lot of work - are you just trying to turn the AC on/off, or something more involved? e.g. what’s your goal?
Remotely turning thr unit on and off. The vessel is 1996 vintage CruiseAir SMX II controllers.
I’m wildly guessing the SMX II controller is the long rectangular white or brown unit with the large four pin white plug in the back?
Two of the pins are +5volts and 0volts. the other two are comms.
One option is to e-mail Flight Components who re-made? these boards. By all accounts they are quite helpful.
Another option is to use one of the cerbo relays to switch the AC power relay off and on. (using applicably rated components) then using node red or similar to swipe left or right on a soft switch on the screen. Temperature parameters could be programmed into the cerbo using temp sensors on the cerbo inputs. Battery parameters or shore genset parameters could also be added. (similar to a hot water diverter system)
Sounds like a great idea.
I am a software guy so if I get the protocol, Node Red will allow it to show up as a device on the VRM portal with full control. Thanx for tips and I will let you know the results
Ok.
If I recall correctly, the company which used to refurbish and test the control boards was “Flight Systems” in the USA. They used to have the odd Dometic troubleshooting manual on the web. If you could get in touch with one of their tech’s I’m confident they would have the answers.
Nowdays Dometic and other suppliers just sell a replacement A288 “Unity Board” that you wire in.