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Carrier Comfort Zone

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    Carrier Comfort Zone

    Has anybody ever gotten something to talk to one of these systems or written a plugin? They use an RS485 bus for control so it should be possible. I have read that there is a program available from Carrier that can talk to them, but I have never seen a copy. I also know that there is a module that will control them for Crestron as well.

    Any info would be appreciated.

    Is the protocol published? If you have a way to connect to the stat and the protocol then it's possible to control it.
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      The protocol is not published and is closely held by the manufacturer. I have 2 of these systems at my business and wanted to read and control them via the LAN, but to date have been unable to get anywhere.

      They do use RS485 for the physical layer between the 'stats and FAU. I spent some time looking at the data streams and found that it's pretty cryptic.

      Carrier has an additional interface (about $1000) which adds an RS232 port to the system that they call their "home automation port" and this is what Crestron uses. After several months of both myself and my installer begging, pleading and cajoling Bryant for the protocol for this port with no results, I gave up.

      Recently, I saw that Carrier (Bryant) was going to release an ethernet interface, but after reading the limited info about it I decided it was just a joke and gave up once again.
      Best regards,

      If you're not out on the edge, you're taking up too much room!
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        This has been a challenge to me as well, however, I've made significant progress. My intention is to program a GUI to control my CZII via iPhon, iPad, or pc. I have sniffed the RS485 data bus and parsed the stream into correct packets. Some fields (bytes) are evident as to their function but the last two bytes are a mystery and I think they might be CRC. As time permits I will continue this endeavor or until the protocol is released.

        I have posted some information at

        Hope to hear from others who might want to do this.



          Comfort Zone II protocol

          Hello all!<O</O

          After recently building a 4000 sq/ft home, I am working on a project to communicate with my Carrier Comfort Zone II system. I have successfully acquired data from the RS-485 communication bus and wrote a Graphical User Interface to capture and parse all the zone room temperatures and set points.<O</O


          You can follow my progress at HVAC-Talk here;<O</O

          I would greatly appreciate any assistance in interpreting the Comfort Zone II protocol.<O</O

          Warm regards,<O</O



            Carrier Comfort Zone protocol

            I had this protocol in my hand at one point a couple of years ago before I knew the value of it. I was searching for PDFs of the manuals for my zone controller and found it deep in a list of documents on the carrier web site.

            I'm not a programmer, but remember at the time thinking "Wow, with the command set laid out like this it would be no trick for me to get this integrated into Homeseer if i was able to write something". Knowing that I couldn't write the app, though, I treated it as a curiosity and went back to my manuals.

            I will dig around...maybe I saved a copy when I saved the manuals. I'd love to get at the zone controller from Homeseer.


              The communication board that is available contains an ascii protocol for IP or RS-232. It retails at $900 and wholesales at $350. I have the ascii protocol, but it is of no real value for the RS-485 communication between the furnace and thermostat. At one level it does provide the information that is available, but that can be easily seen from the UI at the thermostat.


                Communications board

                What does the $900 communications board do? Is there some web or command line UI there, or is it just getting to RS485 bus from RS232 or ethernet?

                I'd be interested in a copy of the protocol if you'd care to PM me. I can get to RS485 easily enough, but I need to know what to say once I have the floor.


                  Model #

                  What's the model number for that communications board?


                    DaveG & Michael,

                    Any luck finding the PDF for the Carrier Comfort Zone II protocol?
                    I'm going to revisit my efforts in parsing the data stream. I've been successful at reading and interpreting most of the 14 to 22 bytes.

                    Keep Chillin'


                      Documenting protocol

                      Several of us interested in reverse engineering this protocol have started a wiki to document our progress. Please feel free to share any knowlege you may have aquired in your research:


                      There is also an example parser for the serial stream as well as a local implementation of Carrier's webservice for anyone with a more recent net-enabled thermostat.


                        Great work!
                        I'm not sure this will work for the Comfort Zone II series controller protocol.

                        Keep up the outstanding work!


                          I realize that this is an old topic but I was wondering if anyone else with a Carrier Comfort Zone II/Bryant Zone Perfect Plus 2 would be interested in working with me to get some control from HomeSeer going. It seems like there are 2 complete and very promising looking projects that will completely control the system now: