Adaptec 2930U User Guide - Page 52

Terminating the SCSI Bus

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Understanding SCSI To determine if your SCSI device supports the SCAM protocol, check the SCSI device's documentation. To enable SCAM support, see Chapter B, Configuring the SCSI Card 2930CU with SCSISelect. Terminating the SCSI Bus To ensure reliable communication on the SCSI bus, both ends must be terminated. Termination prevents the signal from bouncing off the end of the cable and interfering with itself. If the SCSI Card 2930CU is connected at one end of the SCSI bus, you must terminate the device at the other end. If the SCSI Card 2930CU is connected in the middle of the SCSI bus, it will not terminate itself and you must terminate the SCSI devices connected to both ends of the SCSI bus. The method for terminating a SCSI device varies. Refer to the SCSI device's documentation for instructions on how to enable or disable termination. Here is some general information about termination: I You control termination on internal SCSI devices by manually setting a jumper on the device or by changing the position on the cable. The internal SCSI device at the end of the cable must be terminated. I Usually, you control termination on external SCSI devices by installing or removing a SCSI terminator module, or by setting a switch on the back of the device. The external SCSI device at the end of the cable must be terminated. I By default, termination on the SCSI Card 2930CU is set to Automatic. Adaptec recommends that you keep this setting. To manually set termination on the SCSI Card 2930CU, see Chapter B, Configuring the SCSI Card 2930CU with SCSISelect. I Most SCSI devices come from the factory with termination enabled. Some SCSI devices include a terminator block or passthrough terminator. See your SCSI device's documentation for information on enabling and disabling termination. A-3

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A-3
Understanding SCSI
To determine if your SCSI device supports the SCAM protocol,
check the SCSI device’s documentation.
To enable SCAM support, see
Chapter B,
Configuring the SCSI Card
2930CU with SCSISelect
.
Terminating the SCSI Bus
To ensure reliable communication on the SCSI bus, both ends must
be terminated. Termination prevents the signal from bouncing off
the end of the cable and interfering with itself.
If the SCSI Card 2930CU is connected at one end of the SCSI bus,
you must terminate the device at the other end.
If the SCSI Card 2930CU is connected in the middle of the SCSI bus,
it will not terminate itself and you must terminate the SCSI devices
connected to both ends of the SCSI bus.
The method for terminating a SCSI device varies. Refer to the SCSI
device’s documentation for instructions on how to enable or
disable termination.
Here is some general information about termination:
■
You control termination on internal SCSI devices by manually
setting a jumper on the device or by changing the position on
the cable. The internal SCSI device at the end of the cable must
be terminated.
■
Usually, you control termination on external SCSI devices by
installing or removing a SCSI terminator module, or by setting a
switch on the back of the device. The external SCSI device at the
end of the cable must be terminated.
■
By default, termination on the SCSI Card 2930CU is set to
Automatic
. Adaptec recommends that you keep this setting. To
manually set termination on the SCSI Card 2930CU, see
Chapter B,
Configuring the SCSI Card 2930CU with SCSISelect
.
■
Most SCSI devices come from the factory with termination
enabled. Some SCSI devices include a terminator block or pass-
through terminator. See your SCSI device’s documentation for
information on enabling and disabling termination.