I need to buy another U160 68-pin internal cable. I may have up to 5
drives, but doubt I will normally do that. Normal now is 3. Some cables
come with the terminator built into them, and others just have
connectors so you have to buy a terminator and plug it into the last
position.
Is one way considered better than the other? Maybe the separate
terminators are better quality or they can be placed closer to the last
drive? Or is it just better to stay with a name brand cable maker?
Jack Bauer wrote:
>
> I need to buy another U160 68-pin internal cable. I may have up to 5
> drives, but doubt I will normally do that. Normal now is 3. Some cables
> come with the terminator built into them, and others just have
> connectors so you have to buy a terminator and plug it into the last
> position.
>
> Is one way considered better than the other? Maybe the separate
> terminators are better quality or they can be placed closer to the last
> drive?
The terminator must be always at the end of the cable, not close to the
"last" drive. Therefore the position is no argument for a separate
terminator in your case. The capacitance may be lower without the
additional connector (this is better).
> Or is it just better to stay with a name brand cable maker?
Yes. The cheap noname cables sometimes don't have the impedance that is
required by the SCSI standard. If this is the case, the best terminators
won't work correctly.
In article <g3g0c2$d8g$1@news.parasun.com>, Jack Bauer <jb@nowhere.com> wrote:
>I need to buy another U160 68-pin internal cable. I may have up to 5
>drives, but doubt I will normally do that. Normal now is 3.
>Some cables come with the terminator built into them,
>and others just have connectors so you have to buy a terminator
>and plug it into the last position.
>Is one way considered better than the other?
It's been a while since I last cabled SCSI drives
but I'm revisiting that since I'm backing them all up.
I found it simpler (for me!) to use a cable
with the permanent terminator at the end.
That way there's NEVER a reason to fuss with termination
(such as enabling termination on the drive at the cable end,
then having to remember to enable termination
when that device is swapped out).
It's very consistent: NOTHING else provides termination.
Using a 5 connector cable with built-in termination is
neat and easy: just roll up the unused end and connectors!
Jack Bauer wrote:
> I need to buy another U160 68-pin internal cable. I may have up to 5
> drives, but doubt I will normally do that. Normal now is 3. Some cables
> come with the terminator built into them, and others just have
> connectors so you have to buy a terminator and plug it into the last
> position.
>
> Is one way considered better than the other? Maybe the separate
> terminators are better quality or they can be placed closer to the last
> drive? Or is it just better to stay with a name brand cable maker?
>
> Thanks
OK guys, now WHERE would you suggest I buy a quality cable from?
The online choices I have found so far are:
SCSI Source (AKA PC-Pitstop)
SCSI4me
MC Price Breakers
2 of the 3 have feedback at resellerratings.com; SCSI for me is bit
questionable. PC-Pitstop has a lot of feedback and seems highly rated,
yet their SCSI cables appear to be no-name.
On 20 Jun 2008 11:21:50 -0400, jeffj@panix.com (Jeff Jonas) wrote:
|>
|>Using a 5 connector cable with built-in termination is
|>neat and easy: just roll up the unused end and connectors!
I thought the (modular) scsi terminator would have to be within
3"-->4" past the last drive and that would do it....
Now I'm getting the thought that the (modular) scsi terminator's
capacitors are not really working if they don't stop/reflect the signals at
termination point.
I would think then that cutting (with a very sharp instrument) the
cable very close to the connector is a good solution in some cable length
situations?
"R. LaCasse" wrote:
> On 20 Jun 2008 11:21:50 -0400, jeffj@panix.com (Jeff Jonas) wrote:
> >
> > Using a 5 connector cable with built-in termination is
> > neat and easy: just roll up the unused end and connectors!
>
> I thought the (modular) scsi terminator would have to be within
> 3"-->4" past the last drive and that would do it....
No, it must always be placed at the end of the cable. Otherwise the
signal is not absorbed correctly.
> Now I'm getting the thought that the (modular) scsi terminator's
> capacitors are not really working if they don't stop/reflect the
> signals at termination point.
The terminator is mainly resistive, its capacitance is parasitic and
ideally zero.
> I would think then that cutting (with a very sharp instrument) the
> cable very close to the connector is a good solution in some cable
> length situations?
It is possible to cut the cable after the terminators connector. But
this is not necessary, it is no drawback to simply put it at the end of
the cable (if the terminator works correctly it doesn't matter what
distance the signals had to run towards the terminator before they are
absorbed).
On Mon, 14 Jul 2008 09:34:21 +0200, Michael Baeuerle
<michael.baeuerle@stz-e.de> wrote:
|>"R. LaCasse" wrote:
|>> On 20 Jun 2008 11:21:50 -0400, jeffj@panix.com (Jeff Jonas) wrote:
|>> >
|>> > Using a 5 connector cable with built-in termination is
|>> > neat and easy: just roll up the unused end and connectors!
|>>
|>> I thought the (modular) scsi terminator would have to be within
|>> 3"-->4" past the last drive and that would do it....
|>
|>No, it must always be placed at the end of the cable. Otherwise the
|>signal is not absorbed correctly.
|>
I usually term the HDD but the externals are obviously termed at the
end.....
|>> Now I'm getting the thought that the (modular) scsi terminator's
|>> capacitors are not really working if they don't stop/reflect the
|>> signals at termination point.
|>
|>The terminator is mainly resistive, its capacitance is parasitic and
|>ideally zero.
|>
|>> I would think then that cutting (with a very sharp instrument) the
|>> cable very close to the connector is a good solution in some cable
|>> length situations?
|>
|>It is possible to cut the cable after the terminators connector. But
|>this is not necessary, it is no drawback to simply put it at the end of
|>the cable (if the terminator works correctly it doesn't matter what
|>distance the signals had to run towards the terminator before they are
|>absorbed).
|>
That's just it, ........ sometimes,...I figure the shorter the bus
distance the better, .........just to be safer
|>
|>Micha
Merci Beaucoup avec sa, .............sometimes when you get to
involved, the simplest things are overlooked, and get all jumbled up....
R. LaCasse wrote in news:dskk74pvvvuovj3eq4o8agn2tdshvmpi29@4ax.com
> On 20 Jun 2008 11:21:50 -0400, jeffj@panix.com (Jeff Jonas) wrote:
>
> > >
> > > Using a 5 connector cable with built-in termination is
> > > neat and easy: just roll up the unused end and connectors!
> I thought
That appears to be a problem. Are you any good at thinking?
> the (modular) scsi terminator
What about the integrated one?
> would have to be within 3"-->4"
Anything particular about that 3"-->4" ?
> past the last drive and that would do it....
What exactly made you think that, do what?
> Now I'm getting the thought
You should have that looked after. Something is not quite right.
> that the (modular) scsi terminator's
> capacitors
Capacitors?
> are not really working
> if
if?
> they don't stop/reflect the signals at termination point.
Are the capacitors working if the signals at termination point are stopped? What exactly switches them on and off to make them work
or not.
>
> I would think then that cutting (with a very sharp instrument)
Some people call that a scalpel.
> the cable very close to the connector is a good solution in some cable
> length situations?
What 'cable length situations' would that be, particularly?
Michael Baeuerle wrote in news:tcjsi5-vg3.ln1@micha.freeshell.org
> Jack Bauer wrote:
> >
> > I need to buy another U160 68-pin internal cable. I may have up to 5
> > drives, but doubt I will normally do that. Normal now is 3. Some cables
> > come with the terminator built into them, and others just have connectors
> > so you have to buy a terminator and plug it into the last position.
> >
> > Is one way considered better than the other? Maybe the separate
> > terminators are better quality or they can be placed closer to the last
> > drive?
>
> The terminator must be always at the end of the cable, not close to the
> "last" drive. Therefore the position is no argument for a separate termi-
> nator in your case.
> The capacitance may be lower without the additional connector
> (this is better).
Nope.
>
> > Or is it just better to stay with a name brand cable maker?
> Yes. The cheap noname cables sometimes don't have the impedance that is
> required by the SCSI standard.
And you would know this how?
> If this is the case, the best terminators won't work correctly.
>
>
> Micha
Michael Baeuerle wrote in news:u4crk5-kvm.ln1@micha.freeshell.org
> "R. LaCasse" wrote:
> > On 20 Jun 2008 11:21:50 -0400, jeffj@panix.com (Jeff Jonas) wrote:
> > >
> > > Using a 5 connector cable with built-in termination is
> > > neat and easy: just roll up the unused end and connectors!
> >
> > I thought the (modular) scsi terminator would have to be within
> > 3"-->4" past the last drive and that would do it....
>
> No, it must always be placed at the end of the cable.
> Otherwise the signal is not absorbed correctly.
Terminators do not absorb signal reflection.
They prevent signal reflection by mimicking that the cable is endless.
>
> > Now I'm getting the thought that the (modular) scsi terminator's
> > capacitors are not really working if they don't stop/reflect the
> > signals at termination point.
>
> The terminator is mainly resistive, its capacitance is parasitic and
> ideally zero.
>
> > I would think then that cutting (with a very sharp instrument) the
> > cable very close to the connector is a good solution in some cable
> > length situations?
>
> It is possible to cut the cable after the terminators connector. But
> this is not necessary, it is no drawback to simply put it at the end of
> the cable (if the terminator works correctly it doesn't matter what
> distance the signals had to run towards the terminator before they are
> absorbed).
Internal cable purchase issue 
Linear Mode
