Length of Cables for ESDI Hard Disk Drives

From: Jerome Fine <jhfine_at_idirect.com>
Date: Fri Aug 3 18:40:31 2001

>Richard Erlacher wrote:

> You shouldn't be having a cable length problem with the ESDI drives. The fast
> signals on the data cables (1 per drive) are driven with differential drivers
> capable of considerable length at that bandwidth. In fact, the number 40 feet,
> sticks in my recollection. The signals on the 34-conductor cable aren't
> particularly fast, but aren't driven, typically, with drivers capable of what
> the diff drivers can do. I doubt you use that much cable, that you'd see the
> impact of cable length. If you really think it's the cable, I'd recommend
> switching to a twisted pair ribbon from the typical flat ribbon. It won't help
> much, and what you might try is simply using a different cable. They do fail
> sometimes.
> Dick

Jerome Fine replies:

I am trying again with the same overall configuration, but except for the same
DK515-78 hard drives, the hardware is different in a different BA123. I am
now up to 9 quad boards and it is still working. I expect to add 3 other quad
boards soon.

Except for the 20-pin data cables of which I have only four which are 4 feet long,
right now I am using only 18 inch cables, but the 34-pin cable is a duplicate which
is actually 8 feet long. After I have tested everything with 12 quad boards, I will
put everything from the other BA123 into this one and see if it still works. If it
fails on a specific board, that should identify the problem. Otherwise, it must be
the BA123 box itself.

The biggest part of the problem is that it is being done in the dining room where
there is room to move. (Let's not get back to that problem!) And I have a deadline
of the next time when my kids are coming for supper on Friday!!

Sincerely yours,

Jerome Fine
Received on Fri Aug 03 2001 - 18:40:31 BST