SCSI chains, quick question...

[Ed Fletcher]

Ed Fletcher wrote:
> Vincent Trouilliez wrote:
> 
>> Problem: I have got a SCSI scanner, and an internal SCSI CD writer. I 
>> got the scanner first, 9 months ago, it was working fine. Then I 
>> removed it. Then later I was a given a SCSI CD writer, which
>> worked fine.
>> But today, for the first time, I tried plugging both the CD writer and
>> scanner at the same time.  But at boot, the SCSI card (common Adaptec
>> 2940 affair) times out when trying to detect the devices. CD writer
>> alone no problem, scanner alone no problem, but both at the same time,
>> times out, nothing detected ! :-/
>>
>> I very vaguely (probably wrong), that when you have both internal AND
>> external devices, then the terminator must be placed on the external
>> peripheral ? Or did my brain invite this during some bad dream ?
>> So I tried that :
>>
>> internal CD writer : ID 2
>> scanner : ID 3
>> terminator : on the scanner.
>>
> 
> Just going from memory here, but isn't there a setting in the adapter 
> that allows you to disable an internal terminator?
> 
> I've got an old Adaptec AHA-2842VL that I no longer use.  IIRC, all the 
> settings (including onboard termination) were controlled via the cards 
> bios.
> 
> An onboard terminator would be in the middle of the scsi chain and give 
> you the symptoms you're describing.
> 
> HTH,
> Ed

Jeez, I hate having to reply to my own message.

But I should add that you need a terminator at each end of the chain. 
The onboard one is for when the chain goes in only one direction. 
Disable it when two scsi cables are attached.

Ed
-- 
Ed Fletcher
ed at fletcher.ca

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