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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


x86 Platform RJ-45 Serial Port Loopback Connector

Use the following wiring instructions for x86 platform RJ-45 serial port loopback connectors.


FIGURE A-17 x86 Platform RJ-45 Serial Port Loopback Connector


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-18 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-19 9-Pin Female Single-Port Loopback Plug Wiring Diagram


9-Pin Male DB-9 External Loopback Connector

Use these wiring instructions for male 9-pin DB-9 external loopback connectors.


FIGURE A-20 9-Pin Male DB-9 External Loopback Connector Wiring Diagram


The signals and names for the DB-9 connector are as follows.

Pin Name

Signal

1

DCD

Data Carrier Detect

2

RxD

Receive Data

3

TxD

Transmit Data

4

DTR

Data Terminal Ready

5

SGND

Signal Ground

6

DSR

Data Set Ready

7

RTS

Request To Send

8

CTS

Clear To Send

9

RI

Ring Indicator


9-Pin Female DB-9 External Loopback Connector

Use these wiring instructions for female 9-pin DB-9 external loopback connectors. Use this loopback connector with the test on x86 platforms.


FIGURE A-21 9-Pin Female DB-9 External Loopback Connector Wiring Diagram




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