IBM 84875MU, User Manual, Page: 66 / 160

The hot-swap-drive backplane controls the SCSI IDs for the internal hot-swap drive
bays. However, when you attach an external SCSI device to an optional SCSI
adapter, you must set a unique ID for the device. See the information that comes
with the device for instructions on setting its SCSI ID.
You can install four internal SCSI devices using the SCSI signal cable that comes
with some server models. If you plan to attach external SCSI devices, you must
order an additional SCSI cable, remove the SCSI knockout from the rear of the
server, and connect the new cable from the system board to this opening. To select
and order the correct cables for use with external devices, contact your IBM reseller
or IBM marketing representative. When using an optional SCSI adapter, you must
also connect the SCSI adapter to the SCSI LED connector on the system board to
receive an indication of SCSI hard-disk drive activity (see “System-board internal
connectors” on page 70). For information about the maximum length of SCSI cable,
see the American National Standards Institute (ANSI) SCSI standards on the ANSI
Web site at http://www.ansi.org/. Adhering to these standards will help to ensure
that the server operates correctly.
Universal Serial Bus connectors
Use a Universal Serial Bus (USB) 2.0 connector to connect a USB device. USB 2.0
technology transfers data at up to 480 Mb per second (Mbps) with a maximum of
127 devices and a maximum signal distance of 5 meters (16 ft) per segment (if the
device that is attached to the server is a USB 2.0 device). If multiple USB devices
are attached to the server, the USB hub must be 2.0; otherwise, all USB 2.0
devices will transfer data at 12 Mbps. Using Plug and Play technology, USB devices
are configured automatically. The following illustration shows a USB connector.
1 4
Use a 4-pin cable to connect a device to a USB connector. If you need to connect
more USB devices than the server has USB connectors for, use a USB hub to
connect additional devices.
If you connect a PS/2 (non-USB) keyboard to the keyboard connector, USB ports
and devices are disabled during POST.
If you connect a USB keyboard that has a mouse port, the keyboard emulates a
mouse, and you cannot disable the mouse settings in the Configuration/Setup Utility
program.
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xSeries 206 Type 8482 and 8487: Hardware Maintenance Manual and Troubleshooting Guide