From owner-freebsd-questions Mon May 27 20:27: 4 2002 Delivered-To: freebsd-questions@freebsd.org Received: from raq02.vbcomm.net (raq02.vbcomm.net [208.178.120.34]) by hub.freebsd.org (Postfix) with ESMTP id 1F3ED37B414 for ; Mon, 27 May 2002 20:26:53 -0700 (PDT) Received: from mrincubator.org (vpn.ckhlaw.com [208.178.123.53]) by raq02.vbcomm.net (8.9.3/8.9.3) with ESMTP id XAA14742; Mon, 27 May 2002 23:26:36 -0400 Message-ID: <3CF2F8F7.336D6967@mrincubator.org> Date: Mon, 27 May 2002 23:26:47 -0400 From: Mark Filipak X-Mailer: Mozilla 4.77 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: "Karel J. Bosschaart" Cc: freebsd-questions@FreeBSD.ORG Subject: Re: scsi error while burning CD References: <20020525155417.A97878@wop21.wop.wtb.tue.nl> <3CEFDA56.DA462413@mrincubator.org> <20020527132713.A2754@wop21.wop.wtb.tue.nl> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG "Karel J. Bosschaart" wrote: > > On Sat, May 25, 2002 at 02:39:18PM -0400, Mark Filipak wrote: > > > 4 - Is terminator power enabled on the SCSI controller card? > > Yes. This was correct for the old situation without scanner, but with > the scanner attached it should be disabled. No. You are confusing the terminator with terminator power. They are two different things. A healthy SCSI bus generally needs both terminators and terminator power. Terminators =========== **Both ends** of the SCSI bus must be terminated. Since your other SCSI devices are internal and now you are adding an external scanner, your situation probably looks like this Without scanner --------------- ________ _____________ / \ / \ /__________\ _____________ \ / | | \| | \ | | | | | | __ __=====__ __=====__ __=====_______| | term. || | | terminator | | enabled || | | enabled || | || | | || | || | |_ ____| |_________||_________| |_______| | | SCSI drives SCSI card With scanner ------------ ________ _____________ / \ / \ /__________\ _____________ \ / | | \| | \ | | | | | | __ ______________ __=====__ __=====__ __=====_______| | | | term. || | | terminator | ________ | | | enabled || | | DISABLED || || terminator | | || | | ||________|| enabled | | || | |_ ____| | | |_________||_________| |_______| | |______________| | SCSI drives SCSI card scanner Whenever the scanner is *not* plugged into the SCSI bus (top picture), you must re-enable the terminator on the SCSI card. (If the SCSI to the scanner is 'narrower' than the SCSI supplied by the SCSI card, then the situation gets a little more complex... see "Width of External SCSI Bus", below.) The terminator needs to be powered by terminator power in order to work. Terminator Power ================ Terminator Power is voltage that is supplied by the SCSI card to power the terminators. Most internal SCSI drives don't need terminator power since the drives are always powered up and will supply terminator power if the SCSI card doesn't, but an external SCSI device always needs terminator power. Some SCSI cards supply terminator power automatically but some require you to set a jumper. See your SCSI card documentation. If terminator power is *not* supplied by the SCSI card, then when you turn the power off on the scanner its end of the SCSI bus will no longer be terminated even though it is still connected to the external SCSI bus. This is true regardless of whether the scanner termination is active or passive (i.e, electonic terminator or purely resistive terminator). So be sure that your SCSI card is configured to supply terminator power. If your external SCSI connector is a SCSI-2, 50 pin connector (8 data bits plus parity bit), then terminator power should be present on pin 26. If your external SCSI connector is a SCSI-3, 68 pin connector (16 data bits plus 2 parity bits), then terminator power should be present on pins 17, 18, 51, and 52. I think terminator power is always enabled for the Adaptec 2940. Width of External SCSI Bus ========================== You mentioned that your SCSI card is an Adaptec 2940. You failed to mention whether it is a 2940UW, which is SCSI-3 (aka: SCSI wide, i.e., 68 pin), which has 16 data bits. Assuming that it is, and assuming that your scanner is SCSI-2 (i.e., 50 pin), which has 8 data bits, you will need to enable the high byte terminator on the 2940 and disable the low byte terminator on the 2940. Hit Ctrl-A during SCSI signon to enter the SCSI BIOS and then configure the 2940's terminators appropriately. Good luck -- Mark To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message