I concur - you can do everything the wrong way with rs485 and all is
fine at low bitrates.  If you have a CRC check on your messages, and a
retry mechanism of some sort (maybe an acknowledgement response and if=20
this ack is not seen within a timeout period, a retry), you'll be in=20
fine shape.
J

Mike Harrison wrote:
> On Sat, 06 Jul 2013 16:42:58 -0400, you wrote:
>
>> I will be building a small network of 4 clients to send one of the
>> house's 4 heating/cooling zones temperature and humidity to a
>> central processor. The client likely will be 18F1320, and the
>> processor 18F4320 since I have a few laying around, but could
>> consider something different. The client will also have a LCD
>> display. The processor will based on temperature and humidity sent
>> the house HVAC zone controller and humidifier signals (24VAC) via
>> relays based on current set conditions.
>>
>> The 4 zone lengths from the processor range from 10 to 50 feet and
>> planning to use cat-5 cable. 2 pair for power to the client, and
>> one pair for RS-485 signal. The network speed can be very slow,
>> even down to 300 baud, since 1 message from each client in 1second
>> and a message length of maybe 20 characters at most would be a
>> lot.
>>
>> The question is: Will a star arrangement work, and what should the
>> terminating resistors be?
>
> That will work fine up to a good few kbaud, no need for terminators
> at that distance
>
>
--=20
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