">I will be building a small network of 4 clients to send one of the=20 >house's 4 heating/cooling zones temperature and humidity to a central=20 >processor." Will the clients be sending asynchronously or will you poll the clients? If you allow the clients to send won't there be a lot of extra code for CSM= A/CD? thanks chuckc -----Original Message----- >From: Carl Denk >Sent: Jul 6, 2013 3:42 PM >To: PICLIST >Subject: [PIC] RS-485 star network ?? > >I will be building a small network of 4 clients to send one of the=20 >house's 4 heating/cooling zones temperature and humidity to a central=20 >processor. The client likely will be 18F1320, and the processor 18F4320=20 >since I have a few laying around, but could consider something=20 >different. The client will also have a LCD display. The processor will=20 >based on temperature and humidity sent the house HVAC zone controller=20 >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=20 >planning to use cat-5 cable. 2 pair for power to the client, and one=20 >pair for RS-485 signal. The network speed can be very slow, even down to=20 >300 baud, since 1 message from each client in 1second and a message=20 >length of maybe 20 characters at most would be a lot. > >The question is: Will a star arrangement work, and what should the=20 >terminating resistors be? > >As an alternative, to each client, I could use 1 pair of the cat-5=20 >outbound and 1 pair inbound, and make it one long (less than 200')=20 >network with jumpers at each client to select the continuity to the next=20 >client, and the usual terminating resistors at the end. > > >Trying to keep this very simple and any advice appreciated. >--=20 >http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >View/change your membership options at >http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .