[RndTbl] SCSI cable length

Adam Thompson athompso at athompso.net
Fri Jul 3 17:02:55 CDT 2015

This https://en.wikipedia.org/wiki/Parallel_SCSI#Comparison_table might 
help you narrow it down.

And, quoting Wikipedia:
>         Interoperability[edit
>         <https://en.wikipedia.org/w/index.php?title=SCSI_connector&action=edit&section=10>]
> There are adapters between most types of parallel SCSI connector, and 
> some companies will manufacture custom cables to guarantee having the 
> correct connectors. An adapter from narrow to wide must include 
> termination to work properly.
> Different SCSI standards use the same SCSI connectors as in HVD and 
> LVD SCSI (High Voltage Differential and Low Voltage Differential) . 
> HVD uses 15V while LVD uses 3.3V, so connecting an HVD device to an 
> LVD host bus adaptor can blow the line drivers on the HBA, likewise an 
> HVD HBA connected to an LVD device.
> Similarly, connecting a (slow) SE single-ended device onto a (fast) 
> LVD SCSI chain will cause the HBA to sync down to the lowest speed.
> While interconnectivity of a number of devices may look 
> straightforward, there are many pitfalls, and with older SE devices 
> the cabling length becomes an issue as signal degrades.


On 07/03/2015 04:17 PM, Adam Thompson wrote:
> Not 100% sure either, but IIRC LVDS (and just plain differential) 
> never had its own connector.
> With the advent of ... Ultra160??? everything was lvds anyway.
> I recall a small handful of devices that could do differential or 
> regular based on a jumper or dip switch, over the same connector.
> What's the device?
> -Adam
> On July 3, 2015 4:06:19 PM CDT, Trevor Cordes <trevor at tecnopolis.ca> 
> wrote:
>     I have an external SCSI device that I'd like to plug in on a 10-15' cable.
>     The device has a standard dense 50-pin 2-row connector.  I thought at
>     first that meant for sure LVD, but now I'm thinking it just means ultra.
>     I need LVD to get over 1.5M cable length, according to spec.  LVD lets me
>     go to 12M it appears.  If it's just ultra then I'm SOL, I guess.
>     Is there a way to know what signalling this device uses based just on the
>     connector?  I checked all available interent specs, incl the original
>     manual, for the device and *nothing* specifies anything other than "SCSI".
>     I'm a big SCSI guy, but my memory on the subject is starting to get
>     hazy due to disuse...
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