Question: Customer has 2 (sometimes 3) XDS510WS attached to SCSI bus on SUN platform. They have had problems with the last (third) XDS staying connected.

Answer: Some issues are:

1. Various SCSI specifications (SCSI-1, -2, -3) confuse the situation.
2. SCSI supports up to 6 meter (19 foot) length chains, but with questionable reliability as chain length grows. The wiring internal to XDS510WS (and the Sparc platform itself) contributes to this length. SCSI cables come in various lengths (6 foot and 2 foot versions seem typical).
3. A line termination is required on last XDS510WS in chain. TI"s XDS installation guide (SPNU121A for TMS470) depicts an AMP 749535-2 passive termination. However, an active termination is preferred for multiple XDSs. AMP recommended to me their 750381-1 single-ended active termination, which my customer has ordered but not yet tried. AMP"s web site has information on terminating the SCSI bus.