Special Scsi Interface Features; Connecting Scsi Devices; Scsi Bus Termination - Dawicontrol DC-29160 U3W Mode D'emploi

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4. Special SCSI Interface Features

SCSI stands for small computer systems interface and denotes a general system
interface which because of its device independence enables the connection of various
peripheral devices without requiring detailed knowledge of drive characteristics.
If you have not yet acquired experience in handling SCSI devices, we would like
to direct your attention to some technical special features to simplify installation.

4.1. Connecting SCSI Devices

The SCSI interface of the DC-29160 U3W enables the connection of a total 16
different devices, which includes the DC-29160 U3W, so that a maximum of 15 SCSI
peripheral devices can be connected to the DC-29160 U3W. All the SCSI devices are
connected to each other via a common cable called SCSI bus which transmits the
various commands, data and messages. In this respect, it is necessary for all the SCSI
devices to be given an individual address, the so-called SCSI ID or target ID. This SCSI
ID can be set from 0 to 15 on most devices (mostly via jumpers; most systems reserve
ID 7 for SCSI host adapters).
By no means should two devices have the same ID setting, as each command
will then address both devices. The sequence of SCSI devices connected to the SCSI
bus is of no importance, that is, each ID can be placed at any position of the SCSI bus.

4.2. SCSI Bus Termination

In order for the SCSI
terminators need to be placed at the two physical ends of the bus. These terminators
are either integrated in the SCSI device or need to be added as separate elements, as
only a perfect termination of the cable ends will prevent reflections. There are two types
of terminators, passive and active ones. Passive terminators principally consist of only
a single resistor network, while active terminators are powered by a voltage source and
a voltage regulator. Therefore, SCSI bus load variations can be more easily levelled
out.
For LVD (low voltage differential) host adapters active termination is prescribed
by the SCSI specifications. If the internal and external connections are used
simultaneously, the terminators of the host adapter have to be turned off, as in this
case, the host adapter is no longer placed at the end, but in the middle of the SCSI bus.
During the installation of SCSI devices, you also have to remove or turn off the
terminators placed on them, unless the devices concerned are not connected to the
end of the SCSI bus.
bus to operate perfectly with regard to electricity,
Manual