Maximum lenght of UDMA calbe

  • Thread starter Thread starter Sarenka
  • Start date Start date
18" or 46cm In practice, longer cables can be used when necessary.
Click to expand...

I use 60cm rounded with a single drive (cut down 90cm actually).
I had problems with 90cm and two HDDs. The cable caused enough
CRC errors that the kernel (Linux) decided after some minuted
that the HDD on the end of the cable was defective and disabled it.

It was a cheap rounded 90cm cable though. I may try again
in the future with a 90cm CoolerMaster cable.

Arno
 
Arno said:
I use 60cm rounded with a single drive (cut down 90cm actually).
I had problems with 90cm and two HDDs. The cable caused enough
CRC errors that the kernel (Linux) decided after some minuted
that the HDD on the end of the cable was defective and disabled it.

It was a cheap rounded 90cm cable though. I may try again
in the future with a 90cm CoolerMaster cable.
Click to expand...

It seems to me the newer CoolerMaster cables are of very good quality with
the addition of outer shielding and pull tabs to relieve strain on the
connectors. They make 24" (60cm) lengths.
 
Sarenka said:
What is max length of udma 133 cable? Or where can I find that value?
Click to expand...

Officially it's 18", but 24" almost always works, unless the cable is
made wrongly, as many round ones are, with some signal wires adjacent
to one another rather than isolated by ground wires. Some round
cables even include metal shielding or sheathing, which usually just
adds capacitance, and sometimes that metal isn't even grounded, making
it worse than an unshielded cable (ungrounded metal can act as an
antenna and pick up interference). One maker of round IDE cables
admitted to me that their products were primarily for cosmetic
purposes. The only properly made round cables have each signal wire
paired with a ground wire _and_ twisted together (twisted pair, or
TPO), much like network cable. I believe these will be reliable even
if 36" long because I tried a homemade one 60" long (flat, not round),
and it worked reliably at ATA100 speed (I didn't have an ATA133 drive
to try).
 
Officially it's 18", but 24" almost always works, unless the cable is
made wrongly, as many round ones are, with some signal wires adjacent
to one another rather than isolated by ground wires. Some round
cables even include metal shielding or sheathing, which usually just
adds capacitance, and sometimes that metal isn't even grounded, making
it worse than an unshielded cable (ungrounded metal can act as an
antenna and pick up interference). One maker of round IDE cables
admitted to me that their products were primarily for cosmetic
purposes. The only properly made round cables have each signal wire
paired with a ground wire _and_ twisted together (twisted pair, or
TPO), much like network cable. I believe these will be reliable even
if 36" long because I tried a homemade one 60" long (flat, not round),
and it worked reliably at ATA100 speed (I didn't have an ATA133 drive
to try).
Click to expand...

Now I can play with my BigTower case :)
Great THX to everyone.
 
do_not_spam_me said:
Officially it's 18", but 24" almost always works, unless the cable is
made wrongly, as many round ones are, with some signal wires adjacent
to one another rather than isolated by ground wires. Some round
cables even include metal shielding or sheathing, which usually just
adds capacitance, and sometimes that metal isn't even grounded, making
it worse than an unshielded cable (ungrounded metal can act as an
antenna and pick up interference). One maker of round IDE cables
admitted to me that their products were primarily for cosmetic
purposes. The only properly made round cables have each signal wire
paired with a ground wire _and_ twisted together
Click to expand...
(twisted pair, or TPO),
Click to expand...

TPO stands for thermo plastic insulation, not twisted pair.
 
Folkert Rienstra said:
TPO stands for thermo plastic insulation, not twisted pair.
Click to expand...

My mistake. Plycom told me that it stood for twisted pair after I
questioned the quality of their round cables.
 
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