SCSI Termination Question

[contra53]

my scsi setup is as follows: adaptec 2930, plextor ultra40plex, yamaha 8424 scsi and a hp 4p scanner. the plextor is id 0, the yamaha is id 3 and the hp is id 6. what should i have terminated? should it be the yamaha or the scanner. i don't run the scanner all the time. can i have the yamaha terminated, then use the scanner? do i leave the yamaha not terminated and have the scanner terminated, even though it is not always on?

thanks in advance

 

[Shelgeyr]

Assuming the scanner is connected to the external connector, it needs to be terminated. As for the internal devises, always terminate the devise on the connector furthest away from the adapter card.

 

[ishmael2k]

I am not a SCSI guru but here goes...

First I have to make a couple of assumptions

The scanner is external and thus will need to be terminated if it is the only external device. (Assumption #1)

The Plex and the Yammy are both internal and both are 50pin. (Assumption #2) If so then whichever of these is on the end of the cable needs to be terminated and the other doesn't. (Should not be.)

This looks like the most likely setup with the 2930 you have.

Rob

BTW as I said I am no guru, and have a setup that I can not get to work just to prove it!! :Q

Also I'd give the Plex a different id, 0 is usually reserved for hard drives, in case you ever want to boot off of one.

 

[rommel]

termination needs to be at the end of the scsi chain...if you have nothing outside the box the scsi controller will usually act to terminate itself...it btw is almost always id7....termination does not depend on id number its really physical location that determines it....the purpose of termination is to stop data from bouncing back and forth on the scsi bus...so if you terminate before a device that device can longer get information from the bus...terminate the ends of the chain

 

[corkyg]

Rommel has it stated correctly. Furthermore . . . priority on the SCSI bus is from higher ID # to Lower. IOW, the host adapter as #7 is the highest priority item in the chain. The ID #6, 5, and so forth. 0 and 1 are usually reserved for internal devices only . . . usually bootable HDDs.

 

[contra53]

thanks for the help