12.2. Termination Configuration
The basic rule to remember when configuring this characteristic is that termination is required on
both ends of the SCSI chain. To install a new device as the last device on one of the sides of the
complete cable, you must enable termination on it. If the new device replaces another device that
was previously at the end of the cable, and now is installed on another connector on the bus, you
must disable the termination on the previous device.
If you install an external SCSI device, but had only internal devices so far, you must also disable
the host adapter’s termination. This can be done via software as with the newer adapters, by
removing the (usually three) terminator packs near the host adapter’s SCSI connector, or by
setting a jumper on the host adapter. Clearly, the situation is the same if you previously had only
external devices.
12.3. SCSI ID Configuration
SCSI ID configuration requires the location of the first available free ID. The best way of doing
this is to simply look at your host adapter’s boot-up message and check for free IDs.
Adaptec AHA-1540CF/1542CF BIOS 2.01s
(c) 1993 Adaptec, Inc. All Rights reserved
Press <Ctrl><A> for SCSISelect(TM) Utility!
Target #0 - DEC DSP3085S-B SD16 - Drive C: (80h)
Target #1 - QUANTUM LP425S 606_ - Drive D: (81h)
Target #3 - TOSHIBA CD-ROM XM-3301T
Target #4 - SDI LASERSTOR E5
In this example, ID 2, 5 and 6 are free for new devices. ID 7 cannot be used, as this is the host
adapter. The FFD uses Header to set the ID in a 4-2-1 configuration. The sum of the switch
values determines the ID. For example, if you want a hard disk with ID 0, set all three switches
to OFF.
12.4. Solving Installation Problems
The following is a general list of common problems that may arise when installing the FFD:
•
Unstable termination
: Passive termination with Fast-SCSI devices on the bus.
•
Wrong termination
: Too many devices terminated, or the SCSI bus cable ends are not
terminated.
•
Cables
: Homemade, short, flat ribbon cables with bad contacts or cheap cables, or mixing
round cables with flat cables. Ultra320-compliant cables are required for the FFD.
58
Product Specification and User Manual FFD 3.5" Ultra320 SCSI
43-PS-0305-00 Rev. 2.0
