Seagate Barracuda ST11950N, Руководство по эксплуатации продукта

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Barracuda 1 and 2 Product Manual, Rev. C 69
11.7.3.3 Terminator requirements
ST11950N and ST12550N drives
Internal disc drive I/O termination consists of active circuits with resistor
modules that plug into sockets on the main PCB (see Figure 16). You may
order ST11950N and ST12550N drives with or without the resistor modules
installed to facilitate a particular application. All single initiator/single target
(non-daisy-chain) applications require you to terminate the initiator and disc
drive. Daisy-chain applications require you to terminate only the units at each
end of the daisy chain. All other peripherals on the chain should not be
terminated.
Note. Remove terminator resistor modules where terminators are not
required. Removal of terminator power source selection jumper (see
Figure 16) does not disconnect the terminator resistors from the
circuit.
For single-ended I/O Barracuda applications, the SCSI bus must be termi-
nated at both ends with ANSI SCSI-2 alternative 2 termination (active
termination), especially if the bus will be operated at fast SCSI transfer rates.
Barracuda drives provide active termination as the on-board termination
option.
Note. All terminators used in the daisy chain must be active terminators as
described above.
ST11950W and ST12550W drives
Internal disc drive I/O termination consists of active circuits contained in
permanently mounted IC terminator packs on the main PCB (see Figure 18).
All single initiator/single target (non-daisy-chain) applications require you to
terminate the initiator and drive.
Daisy-chain configurations require you to terminate only the units at each
end of the daisy chain. Do not terminate any other peripheral on the chain.
Note. Remove the Enable Drive Terminator jumper on J4 pins 11 and 12
when terminators are not required.
ST11950ND, ST12550ND, ST11950WD, and ST12550WD drives
Differential I/O Barracuda drives do not have provisions to add terminator
sockets on the PCB. You must provide external termination.
11.7.3.4 Terminator power
You can configure terminator power in four different ways. See Section 10.1
for illustrations that show how to place jumpers enabling each of the following
terminator power configurations:
1. Drive accepts terminator power through SCSI bus pins
ST11950N and ST12550N Pin 26
ST11950W and ST12550W Pins 17, 18, 51, and 52
2. Drive supplies power to the SCSI bus.
3. Drive provides terminator power for optional internal terminator
resistors using the drive’s power connector.
4. Drive provides power to its own terminators and to the SCSI bus
terminator power line (pin 26).