Installed SCSI Zip 250, now computer won't recognize Plex drives!

[HardTech]

I installed a SCSI Zip 250 right now. I have checked the termination and everything. The only thing that bugs me is when the computer boots up, the SCSI card (Adaptec 2930C) doesn't recognize the Zip as being PnP.

At least the computer recognizes the zip, but now my two Plex drives are missing (UltraPlex 40 and 12/10/32S). The UltraPlex's SCSI ID is 1, 12/10/32S is 5, and the SCSI Zip is 6.

 

[cloudchief]

My guess is one of three things:
1. Termination (which you say you checked, double check?)
2. SCSI id
3. Cable length (is one of the drives external?)

edit:
Sorry I guess I read too fast. I see you listed the IDs, and checked termination, so that just leaves my last guess as a thing to check. Like I said is one of the drives external? If it is, then there is a good likelyhood that it is cable length.

 

[SCSI]

At least the compute recognizes the zip, but now my two Plex drives are missing (UltraPlex 40 and 12/10/32S). The UltraPlex's scsi IS is 1, 12/10/32S is 5, and the scsi Zip is 6.

It looks to me that your device ID's priorities are not configured correctly. In general it is better to put slower, but less-used devices at the higher IDs and leave the hard disks at the lower IDs

In order to avoid conflicts when more than one device tries to access the bus, the SCSI bus protocol provides a concept called priority. If two devices both put their IDs on the bus at exactly the same time, the one with the higher ID gets access and the lower one backs off and waits for the bus to be free again. This is one reason that the host adapter is usually assigned ID 7, because it is the most important and heaviest user of the bus.

Another thing to consider is the order of connection on the same cable. You may want the SCSI CDR/RW to be the first w/ID #6, the 2nd SCSI CD-ROM next w/ ID #5, and then the SCSI ZIP last w/ID # 4 and termination at the end of the chain. I am assuming that your HDD is IDE.

 

[bozo1]

SCSI problems are almost always cabling/termination related. The SCSI ID's you have assigned are fine.

 

[HardTech]

hmm... I never heard anywhere about the SCSI ID thing

the Zip drive is external, and the CD drives are internal. The external cable doesn't seem long at all.

 

[mastertech01]

Sometimes you have to use an external terminator on an external device because of total cable length. Sometimes the termination on the external device is not adequate. You might make sure the termination switch is fully switched on..work it back and forth a couple times. I would also go into bios of the SCSI controller and see if termination is set to auto, and maybe experiment with hi/lo termination settings. Is the 25 pin cable hardwired 50 pin at the controller, or are you using some adaptor with the cable? The best setup for that is a true 25 pin to 50 pin cable.

I never had a whale of a lot of luck running external with internal devices when running a lot of them. On average I have 4-6 CD drives and 3 externals. I have 3 controllers in my system. A separate one for my external devices, a 29160 for backup HDD and CDROMs, and a RAID controller for the main OS array.

 

[HardTech]

it's a true 25-50 pin.

argh

 

[SCSI]

Well I did some checking and if cabling is in question then this will at least answer one question. The Adaptec 2930C is a Single-Ended (SE) device AHA-2930, and according to Adaptec here is the cable lengths for SE devices:

"SE" (Single Ended). Also called "Legacy / SE" can be a 25-pin, 50-pin or 68-pin connector.

The Legacy / SE bus segment supports the following cable lengths:

SCSI-1 Synchronous or Asynchronous, 25 or 50-pin - 6 Meters
SCSI-2 Fast Narrow, 50-pin - 3 Meters
SCSI-2 Fast Wide, 68-pin - 3 Meters
SCSI-2 Ultra Narrow, 50-pin - 1.5 Meters with four or more devices on the SCSI chain or 3 Meters for three or less devices on the SCSI chain.
SCSI-2 Ultra Wide, 68-pin - 1.5 Meters with four or more devices on the SCSI chain or 3 Meters for three or less devices on the SCSI chain.

General SCSI information for the Zip® SCSI drive

Make sure your internal devices are terminated at the end of the internal chain. This means no termination on and device internally except the last. Then termination the end of the external chain (SCSI ZIP 250). It should work in this configuartion.

 

[HardTech]

... it is....