From owner-freebsd-questions Tue May 25 7:30:33 1999 Delivered-To: freebsd-questions@freebsd.org Received: from loviatar.webcom.com (loviatar.webcom.com [209.1.28.41]) by hub.freebsd.org (Postfix) with ESMTP id 8CA711574B for ; Tue, 25 May 1999 07:30:30 -0700 (PDT) (envelope-from graeme@echidna.com) Received: from kigal.webcom.com (kigal.webcom.com [209.1.28.57]) by loviatar.webcom.com (8.9.1/8.9.1) with SMTP id HAA30349; Tue, 25 May 1999 07:30:28 -0700 Received: from [204.143.69.29] by inanna.webcom.com (WebCom SMTP 1.2.1) with SMTP id 34413357; Tue May 25 07:26 PDT 1999 Message-Id: <374AB3DE.C07ABB41@echidna.com> Date: Tue, 25 May 1999 10:29:50 -0400 From: Graeme Tait Organization: Echidna X-Mailer: Mozilla 4.5 [en] (Win98; U) X-Accept-Language: en Mime-Version: 1.0 To: Terry Glanfield Cc: freebsd-questions@freebsd.org Subject: Re: console terminal server and power loss References: <9905251324.AA03380@program-products.co.uk> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Terry Glanfield wrote: > > Hi, > > Please forgive me if this is not strictly on topic. > > I have an old 386 that I'm trying to configure as a terminal server > for several Sun's serial consoles. Everything works fine except that > when the power is dropped on the server, a BREAK is sent to all the > serial ports resulting in the Suns dropping down to the boot prompt. > I'm trying to do this on the cheap so switched power supplies is out. > I'm using 3.2-STABLE if that makes any difference. Any other > suggestions gratefully received. For RS-232C communication, "break" is signalled by a prolonged absence of high ("mark") on the transmitted data line - so you can detect a literal line break, or shorted line, etc., that would result in loss of ability to transmit. The Suns may also monitor and react to other control signals that are part of the serial interface. With a bit of effort and some hardware expertise, you could probably cobble something together that would prevent loss of power in the 386 from creating a line break condition. E.g., if DTR (data terminal ready) from the 386 is not true, pull TD (transmitted data), and (any other lines used by the Suns) high. You'd have to be careful that this worked even in transient, ill-defined states that might arise during power-down of the 386. But it would seem much better and easier if the Suns could be configured to ignore line breaks. -- Graeme Tait - Echidna To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message