Re: Urgent help required: Star vs Daisy chain wiring for aircon control am I screwed

["Frank Mc Alinden" <frankmc@xxxxxxxxxxxxxxxx>]

Hi Chris
Can you confirm  that the communication is rs 485 ???....If so
then it  should be ok to star or daisy chain ,although rs485 specs state
daisy chaining......

Frank
----- Original Message -----
From: "christopher purves" <CHRIS_PURVES@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Wednesday, September 28, 2005 10:07 PM
Subject: [ukha_d] Urgent help required: Star vs Daisy chain wiring for
aircon control am I screwed


> OK the story so far:
>
> We have had a whole house Daikin air conditioning system installed(hot
and
> cold). 8 indoor units connected to 2 external units (4 internals to
each
> external). We opted for a touchscreen to control this setup as it
could
> provide timing to turn units on and off along with themostats and so
forth
> so it behaved much like a convetional heating system.
>
> Each unit in the chain (including external units and the touchscreen)
has
> an
> f1 and f2 signal connection.
>
> Originally Daikin told our installer to wire as a 'star' back to the
> touchscreen location which required a single 2 core cable to each
indoor
> and
> outdoor unit back to the touchscreen which of course they did. In
effect
> join all f1's together and all f2's together and attach to f1 and f2
on
> the
> trouchscreen.
>
> However when speaking to Daikin today, Daikin are claiming the
internal
> units must be wired in a daisy chain (one to the next). 4 units daisy
> chained into 1 external unit (so 2 setups like that) and then both
> external
> units back to the touchscreen (again f1's to f1's, f2's to f2's).
Clearly
> the existing wiring does not support this method as there are not
enough
> cores but, I cannot for the life of me understand why a star and a
daisy
> chain should be any differrent ? Electrically it seems the connections
are
> the same.
>
> I would also point out that each unit has an address settable by a
four
> input dip switch.
>
> Can we just ignore their comments and wire it a as a star ?
>
> Certainly CBUS can be wired as either.
>
> Anyone ?
>
> Help greatly appreciated. The installer and I are tempted just to try
it
> but
> given the cost of the equipment we are a little nervous. On the
otherhand
> given that all the decoration is now finished it will cost us
thousands to
> rewire.
>
> Ta
> Chris
>
>
>
>
>
>
> Yahoo! Groups Links
>
>
>
>
>
>