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Reverse Engineering the Trane XR524

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  • Reverse Engineering the Trane XR524

    While I like the Trane XR524 thermostat, I would like to have better control over it from HS3. Many z-wave products publish a list of supported z-wave parameters, but not Trane.

    I recently read on these forums that if you click on the root node of a device, go to the z-wave tab, select a parameter number and submit blank (not zero) for the parameter value, and click "Set", the current value of that parameter will be returned.

    So as an experiment (and with too much time on my hands) I attempted to retrieve the values of all 256 possible parameter values from my Trane XR524 saving these values in a spreadsheet. I then changed one setting on the thermostat - switching schedule mode from run to hold, and looked for values in the parameter set that had changed. I noted that parameter 76 had changed from a '1' to a '0'. Verified by switching the thermostat and checking the parameter again. Then the final step of setting parameter 76 to a '1' or a '0' and finding it sets the appropriate mode on the thermostat.

    So, parameter 76 = Schedule Run/Hold mode, Run = 1, Hold = 0.

    Maybe not all that useful since if you use HS3 for scheduling the thermostat you will probably not ever use the schedule run/hold function. But I bet there are other useful things hidden among the parameters.

    I'm going to keep playing with this to see if I can learn the function of other parameters. I was going to attach the spreadsheet I created to track the information, but apparently spreadsheets are not welcome on these forums (tried .xlsx, .xls, and .csv).

  • #2
    I found two more parameters...

    Parameter 71 is the Maximum Heat Setpoint
    Parameter 72 is the Minimum Cool Setpoint

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    • #3
      Neat.
      Is there ability to know if the thermostat is in 2nd stage Heat - or - 2nd stage Cool via HS with this stat?

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      • #4
        Originally posted by Monk View Post
        Neat.
        Is there ability to know if the thermostat is in 2nd stage Heat - or - 2nd stage Cool via HS with this stat?
        No idea so far...

        There are about 150 parameters that return values. I'm trying to determine what they mean by tweaking the settings from the touch screen of the tstat and seeing which, if any, of the parameters change.

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        • #5
          Wow that is some painstaking dedication, kudos to you.

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          • #6
            Originally posted by Fellhahn View Post
            Wow that is some painstaking dedication, kudos to you.
            As I said earlier, too much time on my hands. I've been busy on other things the last couple of days so haven't put any more time on it. I wish Trane would act in a responsible manner and publish their parameter list. They think this will force people to buy their Nexia hub. It makes me go in the opposite direction. I have two Trane heating and two AC units in my house now. When they need to be replaced in a few years I'll be looking other other brands.

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            • #7
              Originally posted by jayph View Post
              I recently read on these forums that if you click on the root node of a device, go to the z-wave tab, select a parameter number and submit blank (not zero) for the parameter value, and click "Set", the current value of that parameter will be returned.
              I did not know that! That tip and your example enabled me to reverse engineer my Trane TZEMT400 thermostats. After years of cursing the lack of a way to ensure that all 5 of my thermostats were in Run mode, I now have a solution. Thank you!

              Totally agree that this shouldn't be necessary, and that these parameters should be documented.

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              • #8
                Is it possible to post the parameters you've found so far as text? Now that Google has taken over Nest, I'm planning on moving over to a non-cloud base thermostat and this seems like a good choice.

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