SCSI B Cable Pinout

The SCSI B cable uses a shielded 68 conductor connector, using 2 rows of 34 male contacts (0.05" spacing). The pin out for the B cable is shown below. The pinout for the 68-pin connector differs from the cable pinout provided below. The signal-ended B cable has a maximum length of 6 meters. The cable impedance is between 90 and 140 ohms. The minimum conductor size is 28AWG. The 68-conductor cable may be either a flat cable or twisted-pair [for Wide-SCSI] cable.

**SCSI B Cable PinOut**
Pin #	Pin Function	Pin #	Pin Function
1	Ground	2	Ground
3	Ground	4	Data bit 8
5	Ground	6	Data bit 9
7	Ground	8	Data bit 10
9	Ground	10	Data bit 11
11	Ground	12	Data bit 12
13	Ground	14	Data bit 13
15	Ground	16	Data bit 14
17	Ground	18	Data bit 15
19	Ground	20	Parity bit P1
21	Ground	22	-ACKB
23	Ground	24	Ground
25	Ground	26	-REQB
27	Ground	28	Data bit 16
29	Ground	30	Data bit 17
31	Ground	32	Data bit 18
33	TERMPWRB	34	TERMPWRB
35	TERMPWRB	36	TERMPWRB
37	Ground	38	Data bit 19
39	Ground	40	Data bit 20
41	Ground	42	Data bit 21
43	Ground	44	Data bit 22
45	Ground	46	Data bit 23
47	Ground	48	Parity bit P2
49	Ground	50	Data bit 24
51	Ground	52	Data bit 25
53	Ground	54	Data bit 26
55	Ground	56	Data bit 27
57	Ground	58	Data bit 28
59	Ground	60	Data bit 29
61	Ground	62	Data bit 30
63	Ground	64	Data bit 31
65	Ground	66	Parity bit P3
67	Ground	68	Ground

SCSI-1, SCSI-2, or SCSI-3 to provide "FAST" SCSI with an 8 bit Parallel data bus. Refer here for the main SCSI Bus interface page.
With SCSI-2 the "A" may be used alone or with the "B" cable to provide "WIDE" SCSI allowing a 16 or 32 bit data bus. The pin-out for the 'A' cable is listed on the SCSI Bus 'A' connector pinout page.

The "B" Single-Ended cable pin-out is shown above.
On SCSI-3, the "A" cable may be used for an 8 bit data bus. However the new "P" cable is used to provide a 16 bit data path (wide SCSI). To allow 32 bits of data the "P" cable is combined with another new cable called "Q" (wide SCSI). The "Q" cable pinout is listed on the SCSI Bus 'Q' Single-Ended connector or SCSI Bus 'Q' Differential connector page. The pin-out for the 'P' cable is listed on the SCSI Bus 'P' connector page.

Back to the main SCSI Interface Bus page
The SCSI [parallel] bus width is either 8 bits or 16 bits [Wide bus]. Also the bus may be either Single ended or Differential; however the two are mutually exclusive SCSI is a chained parallel bus, cables start at the Host and run from device to device in a chain. SCSI may be used for asynchronous and synchronous transfers; Asynchronous transfers using Start and Stop bits and synchronous transfers using system timing (Hand-Shaking). The data bus also carries one parity bit.

Design Key words: SCSI Physical Interface, Pinout, Bus, Small Computer Systems Interface, SCSI Pinouts, Signal Ended Pinout, Differential Ended Pinout, Pin Out, A Connector, Signal Names, row, Pin Descriptions, Peripheral Computer Hard Drive Data Bus, Parallel data bus, Description, Parallel SCSI, Direct Attached Storage [DAS], Networked Attached Storage [NAS], Storage Area Network [SAN]


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