Re: rescan scsi

Dave Cinege (
Sat, 21 Jun 97 20:53:06 -0500

On Sat, 21 Jun 1997 08:16:21 -0500 (EST), Tsung-Hsiang Hsueh wrote:

>On Sat, 21 Jun 1997, Dave Cinege wrote:
>> On Sat, 21 Jun 1997 11:10:04 +0200 (MET DST), Rogier Wolff wrote:
>> >You are running more than a WATT of power to the terminator.
>> >Disconnecting that might cause inductance to generate voltages that
>> >are much too high for computer components.
>> Uhhhhuuumm. How do pull down resistors build up are charge?
>When you remove the terminator with the SCSI bus still active there is a
>chance that the wave that is travelling on the wire will get reflected.
>It is similar to turning on a hose, and then suddenly obstruct the output!
>The terminator is there exactly to match the impedance so that no waves
>will be reflected back to the transmitters on the SCSI bus.

Of course you don't want to yank the termination while there is bus
activity, but I fail to see even if you did this how it could cause
psychical device damage. (even though your data may be screwed)

The signal bouncing back has not been amplified in anyway, and a signal
within tolerances simply can not hurt anything, not matter how stray it is.

Shooting a jolt of static down the line COULD kill something, but that just
goes back to safe handling pratices and is not indicative of any real
'danager' in swapping devices on the scsi bus.

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