I will poll the clients, so data collision shouldn't be a problem. On 7/7/13 9:11 AM, Charles Craft 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." > 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 C= SMA/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 >> 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 condition= s. >> >> 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? >> >> As an alternative, to each client, I could use 1 pair of the cat-5 >> outbound and 1 pair inbound, and make it one long (less than 200') >> network with jumpers at each client to select the continuity to the next >> 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 .