Scsi Bus Termination - LSI LSI8751SP User Manual

2.2.6 SCSI Bus Termination

The devices making up the SCSI bus are connected serially (chained
together) with SCSI cables. The first and last physical SCSI devices
connected on the ends of the SCSI bus must have their terminators
active. All other SCSI devices on the bus must have their terminators
removed or disabled. Remember that your LSI8751SP is also on the
SCSI bus—its termination is automatically enabled when it is connected
to the end of the bus.
Your peripheral device terminators are usually set with jumpers, resistor
modules, or with a switch on the peripheral. Refer to the peripheral
manufacturer's instructions and to the user's manual for your computer
for information on how to identify the terminator setting of each device
and how to change it.
Caution: The autoenable/disable sensing feature on your LSI8751SP
may enable termination erroneously if it is directly cabled to
another SCSI device or host adapter using the same
sensing method. Your LSI8751SP senses SCSI devices by
detecting the ground signal on conductor 22 of a
50-conductor SCSI cable, or conductor 50 of a
68-conductor SCSI cable.
The LSI8751SP automatically covers SCSI bus termination for four
different bus configurations, depending on the use of connectors J2, J3,
and J4 on the LSI8751SP (see
are:
•
Only for internal SCSI connections,
•
Only for external SCSI connections,
•
Only for internal and external connections,
•
Only for connections to both internal connectors.
Detailed Installation Procedure
Figure 2.1). The four bus configurations
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