ELK M1 A/C rules for poor communications

[jcrack_corn]

I have HAI thermostats hooked to my elk M1 via serial expander. Has been working very well for approx 1 year (i really dont touch the thermostats anymore)...however the house is big and the thermostat for bedrooms side sometimes misses the communication (definitely pushing the limits of rs 232, approx 100ft run, cat 5e).

SO anyway, here is my solution, does anyone see a problem with this or see a better solution? What this does is send the command to set temp to 67 every 3 seconds between 10:30 and 10:35 (just arbitrarily picked those times)....until the thermostat is actually set to 67, then it stops. The ONLY reason i put in 10:30-10:35 is to make sure in the event of some other error it doesnt sit there trying to communicate all day every 3 seconds. That is enough time to send the command 100 times. My true failure rate is probably 1 out of 10 commands, so that should be more than adequate and so far has done the trick. Just want to make sure my Rules are efficient as possible.....any suggestions greatly appriciated.

(the other thermostat is only about 40-50 ft away from serial expander....i can change this in the futher and make them both about 75 feet)...may also switch to apprilaire in the future only for this reliability issue (because it obviously causes problems in Mainlobby that rules cant solve....)

 

[Black Magic]

I’ve had several communication failures from my Elk serial expander to my RCS thermostats. The cable lengths are only about 8 feet long. There is some suspicion that sending multiple commands to the TStat in one rule could cause a transmission failure. I need to test injecting a delay between TStat commands (for example, toggle an unused phantom output).

To workaround my problem, I keep sending TStat set point updates every 5 minutes. Since I’ve programmed my Elk to operate as an HVAC zone controller, much of the logic to temperature control is performed on the Elk. My TStats are just used to control my HVAC (heat/cool/fan). I couldn’t use time based rules because set points could change based off of unpredictable events such as leaving the house (and arming it) or opening a window.

Here is my old code. It has been working reliably for over a year. I think I’ve just tweaked it a bit since I posted it: http://www.cocoontech.com/index.php?showtopic=7149

 

[jcrack_corn]

Crap!

FOrgot to include my rules....here they are!

 

[AO-Brandon]

it is true that the RS232 link is weak, but you forget a few very important things,

1. RS485 is very strong. Using the right cable, the total length of the 485 bus can be up to 3000 ft!
2. The ELK's serial expanders do not necessarily NEED to be located in the same enclosure as the ELK.
3. If you need more length out of the 485 link, you can use the ELK-M1DBHR. It basically acts as a 485 hub / switch ...

B)