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From: david@varian.UUCP (David Brown)
Newsgroups: net.dcom
Subject: Re: hardware flow-control on a VAXen
Message-ID: <579@varian.UUCP>
Date: Tue, 6-May-86 12:20:04 EDT
Article-I.D.: varian.579
Posted: Tue May  6 12:20:04 1986
Date-Received: Thu, 8-May-86 05:52:13 EDT
References: <1747@sdcsvax.UUCP>
Organization: Varian, Walnut Creek, CA
Lines: 20

> Recently, whilst installing our Ungerman-Bass NIUs on one of the VAXen
> here at UCSD, I discovered that certain models of comm line multiplexors
> can do hardware flow control.  In particular, the Emulex CS-11 (which
> does a pretty good job of looking like a DH11) has a switch for each
> line located in the multiplexor panel that when turned on causes the
> UART transmitter to pay attention to Clear-To-Send.  The manual for the
> CS-11 is very clear on this, but I'd never looked.  (Stupid, hah!)
> 

The Able DH/DM multiplexor also has some jumpers (located in the upper
right hand corner) to enable hardware flow control; unfortunately,
the manual is *not* very clear on this.  The mux will stop sending when
it senses pin 22 (RING) go low; we made up special cables at the computer
end tying together pins 22 and 8 (we chose to flow control on CARRIER
(crossed with pin 20 - DTR) on printer lines rather than CTS).

-- 
	David Brown	 (415) 945-2199
	Varian Instruments 2700 Mitchell Dr.  Walnut Creek, Ca. 94598
	{zehntel,dual,amd,fortune,rtech,lll-crg,rtgvax,ptsfa,csi}!varian!david