CAN is relative easy to implement and reliable. If you use PIC18F serials,
you still need to use transceivers per CAN2.0B.

Luke

-----Original Message-----
From: Nelson Hochberg [mailto:nelson@NOSUFFERING.COM]
Sent: Friday, August 16, 2002 3:57 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: [PIC]: CAN or RS-485 ?


I am planning a system with a network of PICs.  The PICs will be daisy
chained together (power and communications) in a standard office environment
(fluorescent lights, networked PCs, telephones, HVAC, etc.)  The PICs will
need to communicate about two bytes (status change of nine LEDs and which
PIC sent the event) every 5-10 minutes.  Two of the events are pretty
important and would need to be acknowledged by the other PICs.  Initially,
the network will be 300' end to end with 18 PICs.  The network could expand
to 2000' end to end and about 100-200 PICs.

I've got it whittled down to either a CAN or RS-485 (unless someone can
convince me another protocol would be better.)  Which one do you think is
better and why.

If I use 18F248/448 do I need to use a transceiver interface such as
PCA82C250 or can the PICs connect to the wires directly?  Any
recommendations for an interface?

I was thinking of using the MAXX485 if I went with RS-485.  Any other
suggestions?

TIA

Nelson
nelson@nosuffering.com
www.nosuffering.com

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