Yes, RS-485 only defines the pin functions and the electrical
parameters. Data formatting and communication protocols are left to
the user to define.  National Semiconductor has RS-485 and RS-422
specific interface ICs.  More info at:
http://www.national.com/design/index.html

Maxim also has some at:
http://www.maxim-ic.com/scripts/cSelector.exe/RS-485/





On Sat, 24 Jan 1998 22:24:27 -0600, you wrote:

->I've seen lots about '485 stuff around her lately.  One recent
posting
->almost made it sound as though there are driver / interface chips
for this
->interface.  The same post made it sound that '485 is strictly a
physical
->spec, and leaves software protocol undefined.
->
->Is this correct?  Does anyone have any WWW links that I might do
more
->research?
->
->Thanks,
->Mitch
->
->
->------------------------------
->Mitch Miller
->mdmiller@nque.com
->------------------------------