Is there a limit to the number of RC90 Thermostats?

[asharperhome]

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

[anogee]

The web site says 127.

[wpiman]

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.

[JLehnert]

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.

[Rick Tinker]

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

[anogee]

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.

[asharperhome]

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

[Rick Tinker]

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