Problems Attaching SCSI-2 Devices to SCSI-3 Adapter

ID: Q168094

The information in this article applies to:

SYMPTOMS

After you attach a 50-pin or Centronics SCSI-2 hard disk, scanner, tape Drive, or other device to a 68-pin SCSI-3 interface, your computer may stop responding or not respond when accessing SCSI bus. You may or may not see any events in the event log indicating a problem.


RESOLUTION

Obtain a proper SCSI-2 to SCSI-3 conversion cable or terminator.


MORE INFORMATION

The third-party contact information included in this article is provided to help you find the technical support you need. This contact information is subject to change without notice. Microsoft in no way guarantees the accuracy of this third-party contact information.

For additional information, please see the following article in the Microsoft Knowledge Base:

Q101352 Properly Connecting SCSI Devices to Windows NT
A SCSI-2 device uses a low control byte, but SCSI-3 devices have both a high and a low control byte. When going from a SCSI-3 interface down to a SCSI- 2 device, the SCSI-3 high byte needs to be terminated while letting the low byte pass through (see Diagram 1). Most SCSI-3 to SCSI-2 cables do not have proper termination and need a special adapter for the high byte to terminate. Unless the documentation that comes with the conversion cable states that it terminates the high byte, proper termination will not happen and possible data corruption can occur.

Diagram 1: 

           SCSI-3 (68-Pin)                               SCSI-2 (50-Pin)

             High Byte            |------------------|
          ------------------------| Terminated       |
                                  |                  |
             Low Byte             |                  |    Low Byte
          -----------------------------------------------------------------
                                  |------------------|

For additional information, please see the following articles in the Microsoft Knowledge Base:
Q154690 How to Troubleshoot Event 9 and 11 Error Messages
Q193242 Windows Hangs at Logo Screen After Attaching External Device
You can also visit Adaptec's Web site:
http://www.adaptec.com/support/connect/index.html
See Connecting 8-Bit and 16-Bit Devices to an Adaptec Wide Host Adapter.

Additional query words: prodnt tape drive ultra wide fast 


Keywords          : kbhw kbsetup kbtshoot ntsetup NTSrvWkst 
Version           : winnt:3.51,4.0
Platform          : winnt 
Issue type        :

Last Reviewed: July 29, 1999