Seagate ST31200N, Руководство по эксплуатации продукта

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50 Product Manual - Hawk 1LP Family SCSI-2 (Volume 1), Rev. C
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11.6.1 DC cable and connector
For models ST31200N/ND and ST3620N, the drive receives DC power through a 4 pin connector (see Figure
11.6-1a for pin assignment) mounted at the rear of the main PCB. Recommended part numbers of the mating
connector are listed below, but equivalent parts may be used (see Table 11.6-1).
Table 11.6.1-1. Mating connector parts
Type of Cable Connector Contacts (20-14 AWG)
14 AWG MP 1-480424-0 AMP 60619-4 (Loose Piece)
AMP 61117-4 (Strip)
For models ST31200NC and ST3620NC, the DC power is routed with the SCSI bus signals through the 80 pin
I/O connector. See Table 11.6.3-1c for power pin assignments.
11.6.2 Physical characteristics
This section defines the connectors, cables, signals, terminators and bus timing needed to implement SCSI.
11.6.2.1 Physical description
The "N" and "ND model drives may be daisy-chained together or with other compatible SCSI devices using
a common cable. Both ends of the cable must be terminated. The model ST31200N/NC and ST3620N/NC
drives implement single ended drivers and receivers. The model ST31200ND drive implements differential
drivers and receivers. All signals are common between all SCSI devices. The drive may be daisy-chained only
with SCSI devices having the same type drivers and receivers. Devices having single ended interface circuits
cannot be on the same Daisy-chain with devices having differential interface circuit. A maximum of 8 SCSI
devices (including the Host) may be daisy-chained together. The SCSI Devices at both ends of the Daisy-chain
are to be terminated. Intermediate SCSI devices shall not be terminated (see Figure 11.6.3-2). Remove the
terminator enable jumper TE on J2 select header, not the terminator power source selector jumper TP (Figure
10.1-1).
"NC" model drives plug into PCB or bulkhead connectors in the Host. They may be connected in a daisy-chain
by the host backplane wiring or PCB circuit runs that have adequate DC current carrying capacity to support
the number of drives plugged into the PCB or bulkhead connectors. A single 80 pin I/O connector cannot
support the DC current needs of several drives, so NO DAISY-CHAIN CABLES should be used. A single drive
connected via a cable to a host 80 pin I/O connector is not recommended.
11.6.2.2 Cable requirements ("N" and "ND" models only)
11.6.2.2.1 Single ended I/O circuits ("N" models)
The maximum total cable length for use with drives having single ended I/O driver and receiver circuits shall
be 6 metres (19.7 ft.) when operating at line data transfer rates of 5 Mbytes/sec or less, and 3 metres (9.85
ft.) when operating at transfer rates greater than 5 Mbytes/sec (FAST SCSI). A stub length of no more than
0.1 metre (0.33 ft.) is allowed off the mainline interconnection with any connected equipment. An ideal
impedance match with cable terminators implies a cable characteristic impedance of 132 ohms (see
11.6.2.2.3). Single ended I/O cable pin assignments are shown in Table 11.6.3-1a.
11.6.2.2.2 Differential I/O circuits ("ND" models)
The maximum total cable length for use with drives having differential I/O drivers and receiver circuits shall be
25 metres (82 ft.). A stub length of no more than 0.2 metre (0.66 ft.) is allowed off the mainline interconnection
with any connected equipment. An ideal impedance match with cable terminators implies a cable characteristic
impedance of 122 ohms (see 11.6.2.2.3). Differential I/O pin assignments are shown in Table 11.6.3-1b.