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Help with SCSI setup please

M

mallik

Senior member
Hi, I have a SCSI setup for my computer, and I'm trying to add a scanner, but it is giving me problems. When I get to the SCSI initialization screen where it recognizes all of the SCSI devices connected to the card, the system just hangs. The SCSI card is an adaptec 2940UW and the scanner is a Scanjet 5p. I have 3 UW SCSI drives to the 68 pin bus and it works fine. The external port on the back of the card is high density 68-pin, and the scanner cable is high density 50-pin, so I got an adapter for that. So this is how it is all set up.

A=adapter
D=drives
S=scanner
*=high density 50-pin to high density 68-pin adapter

A----->D----->D----->D
S----->*A

I hope that's clear. Now I'm not too sure about termination, as I've never really had to mess around with that. The drives have auto termination I believe and everything took care of itself. Now with this scanner and adapter, I'm not sure. I also heard that adaptec cards only like specific adaptec adapters for pin conversion. Not sure if this is true. Can anybody help me? I'm lost. Sorry for the long post.
 
Well, you should start worrying about termination. Adaptec cards seem to work just fine with no termination sometimes if you just have a couple of non-LVD drives, then you add a few too many devices then the whole thing gets funny. I called Adaptec with a similar issue several years ago and they basically called me an idiot and said I needed to properly terminate everything and then low-level format all my drives before they'd talk to me.

Each end of each cable needs to be terminated. The adapter should be set to auto-terminate, which takes care of one end. A lot of 50-pin devices have terminate jumpers. There's a difference between a termination jumper and a term power jumper, though. You need termination. If your scanner can't terminate, you're going to need to get a termated cable or a 3-position cable and a separate terminator.

The way it usually goes is:

68-pin chain: A --> D8 --> D9 --> D10 --> terminator
50-pin chain: A --> D1 --> D2

You can set the term power jumpers on D8, D9, D10 if you have a pretty long cable, but the important part is having a termator at the end of your 68-pin cable and setting the terminate jumper on D2.
 
Yes, the scanner end needs to be terminated. The scanner might have two SCSI connectors on it. One goes to the computer and the other should have a terminator plugged into it. If not, you need to get a cable that has an extra connector to plug a terminator into (unless the scanner has internal termination that can be set by dipswitch/jumpers/etc.).
. Only one device, at each end of the cable(s) should be terminated. Obviously the drive at the end of the internal cable has its internal termination enabled or that chain wouldn't work either. You only use the 'Term Power Enabled' setting if you are using an external terminator.
.bh.

It's Sunday, have some :wine: !
 
Hi, thanks for the help guys. Sorry for all the dumb questions, but this termination thing is a little confusing. I understand that both ends of a cable have to have termination, and that the adapter takes care of it's end of the termination. Now, what's the difference between terminating through jumper settings, and getting an actual physical terminator? What is the term power jumper? My three SCSI drives are all connected on the same 68-pin chain with a four device cable, and either the last drive is set to 'terminate' through jumpers, or all three drives are set to auto.

#=open connector

A---->D1---->D2---->#---->D3

Next, I have a CDRW connected to the internal 50-pin connector with a two device cable. It is the lone drive on this chain, and I have a termination jumper on that drive. That all seems to be working fine. Is there anything wrong with that setup?

A---->#---->CDRW

Now I'm trying to connect my Scanjet 5p scanner to the external port. I needed an adapter to convert the pins though. There are two SCSI ports on the back of the scanner, but I searched for info on the scanner (I don't have a manual for this), and it says that the scanner provides automatic internal termination, as needed. Would I still need an external terminator? Also, the adapter to convert the pins is generic, and somebody told me I might need a specific adaptec branded adapter, because it is designed for this type of thing, and it terminates unused lines (the high bits?). Is this true?

*=pin adapter

A*---->S

Sorry for all the questions.
 
You can only use two of the three connectors on the 2940UW at a time. Solution: pick up a $35 LSI Logic U160 card at Newegg and plop your hard drives onto it 🙂
 
Yup. MB caught that one (which you didn't mention before). There is also a way to do what you want with only cables/adapter. LMK if you want the info on that...
.bh.

It's Sunday, have some :wine: !
 
So it's true? Nuts, what a rip. I think it's a little misleading having the ports, but not being able to use them all at once. Sorry, I forgot to mention the CDRW. So if I disconnected the CDRW temporarily, does that mean the scanner should work? Sure Zepper, if you can give me info on another way to connect it, that would be great, thanks.
 
The other thing here is that I believe the card has only one actual SCSI bus. Plugging in a SCSI-2 scanner or CD-RW drive drags the whole bus and all the devices down to SCSI-2 speeds. If you're going to be spending any more money on this project, let me put in another plug (haha) for that LSI Logic U160 card 🙂
 
Originally posted by: dheffer
man i wish i knew how to use scsi, just so complicated!
Click to expand...
Well, it is and it isn't 🙂 If you're just dealing with modern SCSI hard drives, it's like IDE except with 15 options for Master/Slave instead of two. 😀 The old stuff makes me 😕.
 
haha yeah its the older stuff that really scares me, but that stuff impressed the hell outta me back in the day
as my pc building skills increased, the difference between ata and scsi decreased, so i guess i cant now, sad stuff
oh well, i have an old dual p3 sever with 2 9gb ibm scsi hard drives raid'ed, i just dont understand a lot of the random stuff
 
Cable method:
1- DISABLE termination on the 50-pin burner.
2- Get this strap adapter: 50-pin male IDC to HD 50-pin female slot strap adapter . (You might be able to find this and 50-wire cable on eBay for less.) and maybe a longer 50-wire cable if needed - needs to have a regular 50-pin female IDC (device) connector on the far end to plug into the strap adapter.
3- Connect internal 50-wire cable from card to burner to inside connector of strap adapter (must be in the last position on the cable) and mount adapter strap to any free card opening.
4- Connect HD 50-pin cable to scanner and MAKE SURE there is termination at the scanner.
5- That's it, time for the smoke test! 😉
Tip: Arrange to use the shortest internal and external cables as possible to get the job done.
.bh.

:moon:
 
wow Zepper, that's not what I was thinking, but I'm glad I asked. Your idea is not bad. What I was thinking of doing was that since I have a free connector on my 68-pin cable, I could just get a 68-pin internal to 50-pin internal adapter. Is that acceptable too? Or are there drawbacks to that, such as having four devices on the same cable being too much? Oh and btw, I disconnected my CDRW just to see if the scanner would work, and it detected it fine and everything. Thanks everyone for your help.
 
. Yes, that should work fine too - simplest is always the best. I have one of those on the old Plextor 4220 in my system right now - just didn't think of it.
. Don't forget to disable the internal termination on the burner, or any devices past it on the same cable will disappear.
. Either way, the cost works out about the same unless you would need a new 50-wire cable the other way.
. Seven or more devices on one cable is no problem for SCSI - one of the many reasons I like scuzzy so...
.bh.

:moon:

And here are some other sources for SCSI stuff:
http://www.hypermicro.com (may offer free ground shipping if you mention www.storagereview.com - check the SR site for the latest offer)
http://www.centrix-intl.com
http://www.pc-pitstop.com (offers PayPal as a payment option)
http://www.scsi4me.com (ditto)
http://www.etech4sale.com
and I can usually find stuff for low bucks on eBay.
Cornucopia of SCSI info: http://www.scsifaq.org .
 
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