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From: rick@pcrat.UUCP (rick)
Newsgroups: comp.dcom.modems,news.sysadmin
Subject: Re: Hardware Protocol
Message-ID: <376@pcrat.UUCP>
Date: Tue, 25-Aug-87 22:40:40 EDT
Article-I.D.: pcrat.376
Posted: Tue Aug 25 22:40:40 1987
Date-Received: Thu, 27-Aug-87 04:12:05 EDT
References: <192@caeco.UUCP> <26425@sun.uucp>
Organization: PC Research, Inc., Tinton Falls, NJ
Lines: 32
Keywords: Telebit, TrailBlazer, Modems, UUCP, 'g' Protocol, Mimicry
Xref: mnetor comp.dcom.modems:874 news.sysadmin:342

In article <26425@sun.uucp>, guy%gorodish@Sun.COM (Guy Harris) writes:
> 				RTS/CTS handshaking permits a DCE to control
>the flow of data from a DTE; how does the DTE control the flow of data from the
>DCE?

See my previous postings on this.  In a nutshell, RTS is renamed
"Receiver Ready".  

> Now maybe some boxes listend to RTS and stop sending data when it drops.  IF
> this is a commonly-adhered-to (if non-RS-232-compliant) protocol, it might get
> implemented in a future release; however, you'll definitely have to TURN IT ON
> because it's rather non-standard, to say the least.

Yeah, you got it.  It's non-standard, but its elegant.

> Oh yes, one more thing.  Both the Zilog 8530 SCC chip on the Sun CPU serial
> ports, and the Signetics 2661 on the Systech board, will, when doing RTS/CTS
>flow control, *also* shut the receiver *off* when DCD is dropped!  You can shut
> this off on the SCC, by turning off the bit that enables both RTS/CTS outgoing
>flow control and DCD/receiver-enable switching; however, you can't control them
> independently.  This is another reason not to forcibly turn RTS/CTS flow
> control on.

You'll either have to do RTS/CTS in software, or trade up to a newer model
UART.  May I suggest AT&T's 'ARTI', which has three modes of RTS/CTS
operation (including the non-standard full-duplex EIA flow control),
and autobaud (speed matching) as an extra bonus?

-- 
	Rick Richardson, President, PC Research, Inc.
(201) 542-3734 (voice, nights)   OR   (201) 834-1378 (voice, days)
		seismo!uunet!pcrat!rick