scsi termination question

[Need4Speed]

I've always assumed that an active term was required on a u2 bus...but is this neccesarily true?

Specifically, on a AHA-2940U2 card and a pair of u160 10k drives. Can the drives be terminated internally by running in SE mode?
To make a long story short, I'm looking into get some rounded cables for my SCSI setup. They have two kinds that I am looking at.
one with a connection for a term, and one without a connection for a term. The one without is more readily available and half the cost, since it doesnt include an active term. I'd like to use that one thats easily available, but abviously if this doesnt work, then I'll have to go the other route.

 

[bozo1]

There should be a terminator at the end of the cable. If you don't have any external devices, the host adapter needs to be terminated as well within its BIOS. (or just set to auto)

You have to terminate the cable. If you do not have an LVD cable with termination, you'll drop down to SE mode.

 

[Need4Speed]

that's what i have always thought as well, but how can they claim that the cable without the term connection (ie has 3 physical connectors .. card +2 devices) is LVD/u160, if it doesnt have term at the end of the cable?

 

[Need4Speed]

the only diff between LVD and SE is the max length of the cable right?

 

[bozo1]

Dunno. Maybe it's the same cable without the terminator for people who already have one? Or they are just clueless.
I've tried running on a standard cable as well as an LVD cable without a terminator and I dropped down to SE mode.



<< the only diff between LVD and SE is the max length of the cable right? >>


Nope, different voltages, different signaling. Something about the cable is physically different as well. (dont' know what) I tried a non-LVD cable WITH terminator once, and it didn't fly either.

 

[Need4Speed]

PM me your email addy please....thnx

 

[mastertech01]

SOme people have thier own terminators that are removable so they wouldnt need to buy one that is already terminated. The cable rating doesnt change because it is deleted. You will need a terminator. The terminator delete cable could also be used for UW devices that have their own termination. Cable length rules also have restrictions according to the number of devices run on it.

 

[Need4Speed]

<< SOme people have thier own terminators that are removable so they wouldnt need to buy one that is already terminated. The cable rating doesnt change because it is deleted. >>



As is the case for me. My concern lies with the fact that in the term connection is 6" beyond the last device on the particluar cable I was looking at. I would have assumed that the cables would be identical with the exception of the installed term. But that wasn't the case, the entire cable connection scheme was different making it seem as if the term was not required.

In any event, my original assumption was true in that a term is required. It's just a matter of me being picky and wanting a true 3+1 cable rather than a 3 cable. Just keeps things neater.

thanks for the feedback.

 

[SCSIfreek]

get da cable with terminator nuff said. You'll thank me latta.


--Scsi