I have 1wire on control however I have included a couple of external failsafe relays....and in my case it also takes two outputs to be energised for control action. I control water changes to an aquarium and if something goes wrong I could end up pumping 200 litres of water into the floor!
For your furnace control I'd be placing an external delay off relay on an additional DS2405 output and get the program to provide a pulse train say every 10 seconds to keep the relay energised. (i.e. watchdog timer) Use the DOFF relay contact in series with another DS2405 output to control the furnace. That way if your program stops the external relay will time out thus cutting out the furnace. Or you could have an external relay-timer that limits the time the DS2405 output can be turned on for. i.e. your program cannot hold the DS2405 output on longer than xx minutes without at least pulsing it for a short duration, thus resetting the external timer. just some thought rob ----- Original Message ----- From: "Chris Maresca" <[EMAIL PROTECTED]> To: <owfs-developers@lists.sourceforge.net> Sent: Tuesday, February 19, 2008 8:30 PM Subject: Re: [Owfs-developers] OW.pm (Problems with AAG TAI8558/DS2408 and DS9097U) > Why don't you use something other than 1wire? You can directly wire a > thermocouple to the ADC of an AVR chip, then run RS485 back to a > controller. > > If you really want to make your life easy, don't bother with any of > that, just get a PLC and program that. They are around US$130 and are > programmed using ladder logic on a PC, then run stand alone. Most of > them have ADC inputs and it'll be way easier than using an AVR.... > http://web5.automationdirect.com/adc/Shopping/Catalog/PLC_Hardware/DirectLogic_05/PLC_Units > > > That way, all the control logic is on the PLC and you can send it > commands via a serial connection. Some PLCs even have network > connections as addons... > > Yes, I realize this is a 1wire list, but sometimes you just have to use > the appropriate tool for the job.... > > Chris. > > Matthias Urlichs wrote: >> Hi, >> >> Chris Maresca: >> >>>> (NB: Does anybody know of code for the slave side? >>>> >>> Do you mean on the micro or the PC? I'm assuming the PC. >>> >> >> AVR. >> >> The problem: I'd like to remote-control my heating system with 1wire; >> the issue I'm worried about is safety fall-back if the server crashes. >> Thus, the controller needs to be *somewhat* more high-level than a >> DS2405+relay for the furnace, and a DS2760 for the thermocouple. :-/ >> >> Besides: when the thing turns on, it creates an EM storm that tends to >> disrupt the 1wire communication. Thus, my 1wire master system has to >> suspend bus activity at that time. >> >> > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2008. > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ > _______________________________________________ > Owfs-developers mailing list > Owfs-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/owfs-developers ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
