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Is there a limit to the number of RC90 Thermostats?

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    Is there a limit to the number of RC90 Thermostats?

    Hey everyone - I'm trying to figure out if there is a limit to the number of HAI RC90 thermostats that can be controlled through the serial port. After a bit of playing around and reviewing the great information on this site I figured out how to get one to work; however I need to set up thirteen. Anyone done this before? Anything to look out for?

    Thanks!
    Jeff

    #2
    The web site says 127.

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      #3
      directly to a PC with a comm port?

      I have to install my second one.. it would be nice to not have to eat up another serial port. I am using 6 already.
      HS3 Pro Edition 3.0.0.435 (Windows Server 8.1 on ESXi box)

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        #4
        I can't say specifically, as all my stats are hooked up to a OmniPro panel instead of by PC/serial. However, each stat can be assigned an ID and I'm pretty sure I remember something in a previous thread about the serial protocol being able to handle the addressing.

        My system is described in my profile.
        My system is described in my profile.

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          #5
          Yes, HAI uses a special protocol over the serial interface that is more like an RS-422 implementation. Thus, you can run several thermostats over one serial port. You cannot do all 127, and I think the practical limit was around single digits, but a quick call to HAI's tech support will get you the definite answer. If you bought it from Worthington then their tech guys would know the answer too I think - better yet, Tom Morgan of Worthington's University since he used to work for HAI.

          The address for those thermostats I think works off of the device address. In other words, if you address the thermostat to address 2, then your device in HomeSeer has to have a unit code of 2 - e.g. A2, C2, E2, x2, w2, t2.


          Regards,

          Rick Tinker
          HomeSeer Technologies

          Regards,

          Rick Tinker (a.k.a. "Tink")

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            #6
            The HAI site for the thermostats does say this:

            <BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> Can communicate directly with the RS-232 port of a personal computer – no adapter required. Serial mode protocol: addressable up to 127 units, bi-directional, 1 start bit, 8 data bits, 1 stop bit NRZ. 300 baud data rate. Can communicate continuously without loss of function. Protocol is available from HAI web site. (Serial Mode 2)
            <HR></BLOCKQUOTE>

            The documention also states that on OmniPro II supports 64.

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              #7
              Well I got it up to three and it works like a champ. I'm a little concerned Rick, because you mentioned that Homeseer tracks against the number in the address, which means that I'm limited to nine stats - and I really do need to go to 13. Any suggestions?

              BTW - I'm using a small terminal isolater and pigtailing the comm wires from each stat in parallel with the serial cable. I'd prefer to use something a little less jury rigged with the final implementation. Anything you can recommend? Would a phone termination block work?

              Thanks! Jeff

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                #8
                Actually, unit codes in HomeSeer go up to 99, so T1 through T99 would be 99 thermostats as the unit code is what corresponds to the thermostat address with the RC80/RC100 scripts.

                Not sure I follow how you have things wired. I am guessing that a star configuration of the wiring, even with good cross-connections, is not desireable as opposed to a device-to-device-to-device bus arrangement or a full loop with thermostats being along the loop. The physical wiring of the stats is definitely something HAI can better advise upon.


                Regards,

                Rick Tinker
                HomeSeer Technologies

                Regards,

                Rick Tinker (a.k.a. "Tink")

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