Myles EftosSo, it's been awhile since I've look at this project. I've been busy working on temperature controller for fridges to help make beer and salami. Why is this relevant?
- It's given me some time away to think, and reset my brain (three years is a legit amount of time)
- I've been deep diving on other serial protocols like HLDC, and now I know a little bit more.
So I decided to have a look at my spreadsheet again, and look for some different patterns.
I was pretty happy that I had identified the meaning of two bytes, but the rest didn't seem to make sense. As a thought experiment (maybe a silly one - I already knew the answer), I tried to fit the pattern into something that looked like UART.
The first couple of bytes kind of matched:
This looks a bit like a 7-O-1 (7-bits, Odd parity, 1 end bit), but it fails when I hit the interesting data.
Reverting back to looking at a a high pulse to indicate a start, followed by 8-bits, a parity bit and a single low to indicate the end, it actually works...
The byte sequence looks like this:
0x00 0xA0 0x00 Byte0 Byte1 0xA0 0x01 0xA0
Now THAT is interesting.
So, new hypothesis: 0xA0 acts like some sort of frame boundary - and if you look closely at the data bytes, bit 7 is always low in the first byte, and bit 5 is always low in the second byte, meaning it is impossible for 0x0A to appear in either of those bytes.
UPDATE: Fun fact: 0x0A is traditionally a line-feed character. Not sure what to do with that information yet...
What of the other numbers? I'm not sure yet.
So, some questions to answer:
- Who is the master here? Does the outdoor unit spit numbers at the controller, then yield the line waiting for a command? Or does the controller ask the outdoor unit for it settings?
- How does a slave fit in to this?
If the controller is not plugged in, it displays an error code, so it feels like it is listening for a boundary byte, but what happens after that? Is there a call/response?
Maybe I'll pull out the oscilloscope again over the weekend...
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Hi Nyles,
I am trying to understand the wiring in this Thermo panel. I have the exact one normally it is labelled with Y, G, RH.RC C.... This one is different (3, CN1 and T15). I am trying to install Nest thermo and I am having difficulties to understand the wiring so I can see will it be compatible. First,
what is the volt required to turn this panel ?
which one represent the G (cool wire)? is it the white ?
Kind regards,
Fawaz
Are you sure? yes | no
I've been looking into options for Fujitsu HP control as well.
I have looked at intesis products. They have Wifi, Modbus and KNX translators. In the manual they describe the remote as a master. If no remote is present their translator box must be set as master. This is older documentation. Their new models no longer have the ability to be change from master/slave and are set at the factory.
https://www.intesisbox.com/intesis/product/media/intesisbox_fj-rc-mbs-1_user_manual_en.pdf
Check page 5 of this PDF
This PDF also shows the variables that are accessible
I am happy to try and assist in your efforts here.
Are you sure? yes | no
hi, no need to control the outdoor unit as it must be driven by the indoor one to keep them working by design. the challenge is to drive the indoor unit, I decided to clean the filter today and realized the white cable sends "data" from the wall to the duct unit. I'm automating the rest of the house (shutters, lights, etc) and because this old air con has not remote is a pain to go to the living to turn it off/on set temp, so I decided to bring it to Home Assistant with the other stuff.
May be for me is not important to have full control, just turn on and off I'm fine so less signals to copy. the temp will leave it set in 27C, so if I got sleep it will work on/off OK.
My unit is a Fuji Electric RO-36T1A and eats 20.5 Amp at 220V hence the need to turn it on/off from the bed to sleep without electricity bill nightmares.
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