APPENDIX A

Loopback Connectors

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Loopback connectors are designed for the testing of communication ports. They take the form of either a single plug or a port-to-port cable with some communication connections shorted (looped-back).

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Note - Loopback connectors must be wired properly and connected firmly for the Serial Port tests to work correctly. Miswired, poorly soldered, or missing loopback connectors can cause erroneous diagnostic error messages.

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TABLE A-1 depicts the pin assignments for most loopback plugs and cables that may be used when testing a system.

TABLE A-1

Signal Description	EIA	CCITT #	RS-449 "A" "B"		DIN 8 8-pin round	DB9 9-pin	DB25 25-pin	Direction	Alpha ID
Chassis/Frame Ground	AA	101	1	NC*	NC*	NC*	1	none	AA
Transmit Data (TxDa)	BA	103	4	22	3	3	2	output	BA
Receive Data (RxDa)	BB	104	6	24	5	2	3	input	BB
Request To Send (RTSa)	CA	105	7	25	6	7	4	output	CA
Clear To Send (CTSa)	CB	106	9	27	2	8	5	input	CB
Data Set Ready (DSRa)	CC	107	11	29	NC*	6	6	input/ output	CC

TABLE A-1 (Continued)

Signal Description	EIA	CCITT #	RS-449 "A" "B"		DIN 8 8-pin round	DB9 9-pin	DB25 25-pin	Direction	Alpha ID
Signal Ground (SG)	AB	102	19	NC*	4	5	7	none	AB
Data Carrier Detect (DCDa)	CF	109	13	31	7	1	8	input	CF
Transmit Clock In (TRxCa)	DB	114	5	23	NC*	NC*	15	input	DB
Receive Clock in (RTxCa)	DD	115	8	26	8	NC*	17	input	DD
Data Terminal Ready (DTRa)	CD	108	12	30	1	4	20	output	CD
External Clock Out (TRxCa)	DA	113	17	35	NC*	NC*	24	output	DA
Secondary Data Carrier Detect (DCDb)	SCF	122	NC*	NC*	NC*	NC*	12	input	SCF
Secondary Clear to Send (CTSb)	SCB	121	NC*	NC*	NC*	NC*	13	input	SCB
Secondary Transmit Data (TxDb)	SBA	118	NC*	NC*	NC*	NC*	14	output	SBA
Secondary Receive Data (RxDb)	SBB	119	NC*	NC*	NC*	NC*	16	input	SBB
Secondary Request to Send (RTSb)	SC A	120	NC*	NC*	NC*	NC*	19	output	SCA

NC = No connection

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25-Pin RS-232 Loopback Plug

The RS-232 and RS-423 single-port loopback plug is a specially wired male DB-25 connector. It is plugged in to a serial port in the back of the system under test. The wiring is shown in FIGURE A-1.

FIGURE A-1

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25-pin RS-232 Port-to-Port Loopback Cable

Use these wiring instructions for 25-pin RS-232 and RS-423 port to 25-pin RS 232 and RS 423 port loopback cables (two DB-25 connections). It is plugged into a pair of serial ports in the back of the system under test. Both connectors are male. The wiring is shown in FIGURE A-2.

FIGURE A-2

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8-Pin to 8-Pin Loopback Cable

Use these wiring directions for 8-pin round DIN RS-232 port to RS-423 to 8-pin round-DIN RS-232 and RS-423 port loopback cable (see FIGURE A-3). Both connectors are male.

FIGURE A-3

Pin 8, Receive clock In (DD), remains unconnected.

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8-Pin Loopback Plug

Use these wiring directions for male 8-pin round-DIN RS-232 and RS-423 Single port loopback plugs (see FIGURE A-4).

FIGURE A-4

Pin 8, Receive Clock In (DD), remains unconnected.

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25-pin Port A-to-Port B Loopback Plug

Use these wiring directions for a 25-pin Port A to Port B loopback plug for most systems (see FIGURE A-5).

FIGURE A-5

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25-pin Port A-to-A Port B-to-B Loopback Plug

If your system has a single communication port to connect it to peripherals, use these wiring instructions for making a male 25-pin loopback plug for that communication port (see FIGURE A-6):

FIGURE A-6

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96-Pin Female Loopback Connector

This 96-pin connector (see FIGURE A-7) can be ordered from Sun Microsystems (Part Number 370-1366).

FIGURE A-7

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96-Pin Female Special Loopback Connector

This 96-pin connector (see FIGURE A-8) can be ordered from Sun Microsystems (Part Number 370-1381).

FIGURE A-8

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37-Pin RS-449 Loopback Cable

Use these wiring instructions for a loopback cable for two 37-pin RS-449 synchronous ports (see FIGURE A-9).

FIGURE A-9

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37-Pin RS-449 Loopback Plug

Use these wiring instructions for making a male 37-pin RS-449 loopback plug (see FIGURE A-10). This connector is also available from Sun (Part Number 530-1430).

FIGURE A-10

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9-pin Male Single-port Loopback Plug

Use these wiring instructions for male 9-pin RS-232 and RS-423 single-port loopback plugs (see FIGURE A-11):

FIGURE A-11

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9-pin Female Single-port Loopback Plug

Use these wiring directions for female 9-pin RS-232 and RS-423 single-port loopback plugs (see FIGURE A-12):

FIGURE A-12

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Note - Use this loopback plug with the pcmciatest.

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9-Pin to 25-Pin Port-to-Port Loopback Cable

Use these wiring instructions for a 9-pin RS-232 and RS-423 port to 25-pin RS-232 and RS 423 port loopback cables (see FIGURE A-13). Both connectors are male.

FIGURE A-13

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9-Pin to 9-Pin Port-to-Port Loopback Cable

Use these wiring instructions for 9-pin RS-232 and RS 423 port to 9-pin RS-232 and RS-423 port loopback cables (see FIGURE A-14). Both connectors are male.

FIGURE A-14

Please note that this cable has no Sun part number assigned to it.

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NT to TE Loopback Cable

Using two standard RJ45 connectors, and connect pin1 to pin1, pin 2 to pin 2, and so on, for all pins. This loopback is a "straight-through" connection.