A - A P P E N D I X -

A P P E N D I X A

Loopback Connectors

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).

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.

The following table depicts the pin assignments for most loopback plugs and cables that may be used when testing a system.

TABLE A-1 Loopback Connector Pin Assignments
Signal Description	EIA	CCITT #	RS-449 "A"	RS-449 "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
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)	SCA	120	NC*	NC*	NC*	NC*	19	Output	SCA

*NC = No connection

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.

FIGURE A-1 25-pin RS-232 Loopback Plug Wiring Diagram

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.

FIGURE A-2 25-pin RS-232 Port-to-Port Loopback Cable Wiring Diagram

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. Both connectors are male.

FIGURE A-3 8-Pin to 8-Pin Loopback Cable Wiring Diagram

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

8-Pin Loopback Plug

Use these wiring directions for male 8-pin round-DIN RS-232 and RS-423 single-port loopback plugs.

FIGURE A-4 8-Pin Loopback Plug Wiring Diagram

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

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.

FIGURE A-5 Port A-to-Port B Loopback Plug Wiring Diagram

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.

FIGURE A-6 Port A-to-A, Port B-to-B Loopback Plug Wiring Diagram

96-Pin Female Loopback Connector

This 96-pin connector can be ordered from Sun (part number 370-1366).

FIGURE A-7 96-Pin Female Loopback Connector Wiring Diagram

96-Pin Female Special Loopback Connector

This 96-pin connector can be ordered from Sun (part number 370-1381).

FIGURE A-8 96-Pin Female Special Loopback Connector Wiring Diagram

37-Pin RS-449 Loopback Cable

Use these wiring instructions for a loopback cable for two 37-pin RS-449 synchronous ports.

FIGURE A-9 37-Pin RS-449 Loopback Cable Wiring Diagram

37-Pin RS-449 Loopback Plug

Use these wiring instructions for making a male 37-pin RS-449 loopback plug. This connector is also available from Sun (part number 530-1430).

FIGURE A-10 37-Pin RS-449 Loopback Plug Wiring Diagram

9-Pin Male Single-Port Loopback Plug

Use these wiring instructions for male 9-pin RS-232 and RS-423 single-port loopback plugs.

FIGURE A-11 9-Pin Male Single-Port Loopback Plug Wiring Diagram

9-Pin Female Single-Port Loopback Plug

Use these wiring directions for female 9-pin RS-232 and RS-423 single-port loopback plugs. Use this loopback plug with the pcmciatest.

FIGURE A-12 9-Pin Female Single-Port Loopback Plug Wiring Diagram

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. Both connectors are male.

FIGURE A-13 9-Pin to 25-Pin Port-to-Port Loopback Cable Wiring Diagram

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. Both connectors are male.

FIGURE A-14 9-Pin to 9-Pin Port-to-Port Loopback Cable Wiring Diagram

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

NT to TE Loopback Cable

Using two standard RJ-45 connectors, and connect pin 1 to pin 1, pin 2 to pin 2, and so on, for all pins. This loopback is a "straight-through" connection.

Twisted-Pair Ethernet (TPE) Loopback Cable for Fast Ethernet

Use the following wiring instructions for standard RJ-45 connectors for Fast Ethernet. This loopback cable is used in netlbtest for eri devices.

FIGURE A-15 Twisted-Pair Ethernet (TPE) Loopback Cable Wiring Diagram for Fast Ethernet

TPE Loopback Cable for Gigabit and 10/100 Ethernet

Use the following wiring instructions for RJ-45 connectors for Gigabit and 10/100 Ethernet. This loopback cable is used in netlbtest for Gigabit and 10/100 devices.

FIGURE A-16 TPE Loopback Cable Wiring Diagram for Gigabit and 10/100 Ethernet