Black Box Switch SC120A R2 User Manual

AUGUST 2002  
SC120A-R2  
SC121A  
2 x 2 SCSI Matrix Switch  
CUSTOMER  
SUPPORT  
INFORMATION  
Order toll-free in the U.S.: Call 877-877-BBOX (outside U.S. call 724-746-5500)  
FREE technical support 24 hours a day, 7 days a week: Call 724-746-5500 or fax 724-746-0746  
Mailing address: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018  
 
2 X 2 SCSI MATRIX SWITCH  
NORMAS OFICIALES MEXICANAS (NOM)  
ELECTRICAL SAFETY STATEMENT  
INSTRUCCIONES DE SEGURIDAD  
1. Todas las instrucciones de seguridad y operación deberán ser leídas antes de  
que el aparato eléctrico sea operado.  
2. Las instrucciones de seguridad y operación deberán ser guardadas para  
referencia futura.  
3. Todas las advertencias en el aparato eléctrico y en sus instrucciones de  
operación deben ser respetadas.  
4. Todas las instrucciones de operación y uso deben ser seguidas.  
5. El aparato eléctrico no deberá ser usado cerca del agua—por ejemplo, cerca  
de la tina de baño, lavabo, sótano mojado o cerca de una alberca, etc..  
6. El aparato eléctrico debe ser usado únicamente con carritos o pedestales que  
sean recomendados por el fabricante.  
7. El aparato eléctrico debe ser montado a la pared o al techo sólo como sea  
recomendado por el fabricante.  
8. Servicio—El usuario no debe intentar dar servicio al equipo eléctrico más allá  
a lo descrito en las instrucciones de operación. Todo otro servicio deberá ser  
referido a personal de servicio calificado.  
9. El aparato eléctrico debe ser situado de tal manera que su posición no  
interfiera su uso. La colocación del aparato eléctrico sobre una cama, sofá,  
alfombra o superficie similar puede bloquea la ventilación, no se debe colocar  
en libreros o gabinetes que impidan el flujo de aire por los orificios de  
ventilación.  
10. El equipo eléctrico deber ser situado fuera del alcance de fuentes de calor  
como radiadores, registros de calor, estufas u otros aparatos (incluyendo  
amplificadores) que producen calor.  
11. El aparato eléctrico deberá ser connectado a una fuente de poder sólo del  
tipo descrito en el instructivo de operación, o como se indique en el aparato.  
2
 
NOM STATEMENT  
12. Precaución debe ser tomada de tal manera que la tierra fisica y la polarización  
del equipo no sea eliminada.  
13. Los cables de la fuente de poder deben ser guiados de tal manera que no  
sean pisados ni pellizcados por objetos colocados sobre o contra ellos,  
poniendo particular atención a los contactos y receptáculos donde salen del  
aparato.  
14. El equipo eléctrico debe ser limpiado únicamente de acuerdo a las  
recomendaciones del fabricante.  
15. En caso de existir, una antena externa deberá ser localizada lejos de las lineas  
de energia.  
16. El cable de corriente deberá ser desconectado del cuando el equipo no sea  
usado por un largo periodo de tiempo.  
17. Cuidado debe ser tomado de tal manera que objetos liquidos no sean  
derramados sobre la cubierta u orificios de ventilación.  
18. Servicio por personal calificado deberá ser provisto cuando:  
A: El cable de poder o el contacto ha sido dañado; u  
B: Objetos han caído o líquido ha sido derramado dentro del aparato; o  
C: El aparato ha sido expuesto a la lluvia; o  
D: El aparato parece no operar normalmente o muestra un cambio en su  
desempeño; o  
E: El aparato ha sido tirado o su cubierta ha sido dañada.  
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2 X 2 SCSI MATRIX SWITCH  
TRADEMARKS USED IN THIS MANUAL  
BLACK BOX and the  
Corporation.  
logo are registered trademarks of Black Box  
Microsoft, Windows, and Windows NT are registered trademarks or trademarks of  
Microsoft Corporation in the United States and/or other countries.  
UL is a registered trademark of Underwriters Laboratories Incorporated.  
Any other trademarks mentioned in this manual are acknowledged to be the property of the  
trademark owners.  
4
 
TABLE OF CONTENTS  
Contents  
Chapter  
Page  
1. Specifications ..........................................................................................................7  
2. Introduction ..........................................................................................................10  
2.1 About the SCSI Switch ..................................................................................10  
2.2 Features ..........................................................................................................10  
2.2.1 LCD Panel..............................................................................................11  
2.2.2 Front-Panel Controls ............................................................................11  
2.3 Technical Description....................................................................................11  
2.3.1 Available SCSI Switch Interfaces..........................................................11  
2.3.2 General Hardware Description............................................................12  
2.3.3 Ultra2 SCSI Compatibility ....................................................................12  
2.3.4 SCSI Switch Installation........................................................................12  
3. Installation ............................................................................................................15  
3.1 What’s Included ............................................................................................15  
3.2 AC Line Voltage ............................................................................................15  
3.3 Switch Placement ..........................................................................................15  
3.4 Power Equipment Off....................................................................................15  
3.5 SCSI Interface Cabling ..................................................................................16  
3.6 RS-232 Serial Port Cabling ............................................................................16  
3.7 Ethernet LAN Port Cabling ..........................................................................16  
4. Operator Controls and Indicators ......................................................................17  
4.1 AC Power Switch ............................................................................................17  
4.2 LCD Display, Keypad, and Indicators ..........................................................17  
4.2.1 LCD Display ..........................................................................................17  
4.2.2 Keypad ..................................................................................................18  
4.2.3 Indicators ..............................................................................................18  
4.3 LCD Display Control Menus ........................................................................18  
4.4 SCSI Switch Port Configuration....................................................................21  
4.5 SCSI Switch Default Configuration ..............................................................21  
5. Configuration and Operation..............................................................................22  
5.1 SCSI Cable Interface Requirements ............................................................22  
5.2 Internal Terminator Selection......................................................................22  
5.3 Selecting Internal Terminator Power ..........................................................25  
5.4 Selecting External Terminator Power..........................................................25  
5.5 Serial-Port Pinout ..........................................................................................26  
5.6 LAN/Serial-Port Commands ........................................................................27  
5.7 ASCII Character Reference for SCSI Switch Box Selection........................33  
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2 X 2 SCSI MATRIX SWITCH  
Chapter  
Page  
5. Configuration and Operation (continued)  
5.8 Graphical User Interface (GUI) ................................................................33  
5.9 Connecting Multiple SCSI Switches ..........................................................34  
5.10 Typical Application......................................................................................34  
5.11 Network Control of SCSI Switch ................................................................35  
5.11.1 LAN Port Configuration ..................................................................35  
5.11.2 Cfgswitch Utility................................................................................36  
5.11.3 Apconcmd Utility..............................................................................37  
6. SCSI Technical Information ................................................................................38  
6.1 SCSI Basics......................................................................................................38  
6.1.1 SCSI-1 ....................................................................................................38  
6.1.2 SCSI-2 ....................................................................................................38  
6.1.3 SCSI-3 ....................................................................................................38  
6.1.4 Signal Wiring ........................................................................................38  
6.1.5 Common Problems ..............................................................................39  
6.1.6 Passive Terminators ..............................................................................39  
6.1.7 Active Terminators................................................................................39  
6.2 SCSI Installation Tips ....................................................................................39  
6.3 SCSI Interface Signal Descriptions ..............................................................40  
7. Troubleshooting....................................................................................................50  
7.1 Calling Black Box ..........................................................................................50  
7.2 Shipping and Packaging................................................................................50  
6
 
CHAPTER 1: Specifications  
1. Specifications  
SCSI Interface  
Maximum Port Switching Delay: 3 ns  
Maximum Signal Skew: 2 ns  
Internal Terminator Power: 1 amp  
Rear-Panel Connectors: 68-pin high-density  
SCSI-1, SCSI-2, and SCSI-3 (also Ultra160 SCSI [“Ultra3 SCSI”] for SC120A-R2),  
SPI-2 compatible; asynchronous and synchronous compatible; conforms to  
ANSI X3.131 and X3T9.2  
Single-Ended (SE) SCSI (SC120A-R2 Only)  
Maximum Data Rate (8-bit Narrow): 20 MBps  
Maximum Data Rate (16-bit Wide): 40 MBps  
Maximum Port Cable Length: 6 meters (20 ft.)  
Internal Terminator Impedance: 100 ohms  
Terminator Disconnect Capacitance: 3 pF  
Active Internal Bus Termination  
Differential (DE) SCSI (SC121A Only)  
Maximum Data Rate (8-bit Narrow): 40 MBps  
Maximum Data Rate (16-bit Wide): 80 MBps  
Maximum Port Cable Length: 25 meters (82 ft.)  
Internal Terminator Impedance: 110 ohms  
Terminator Disconnect Capacitance: 5 pF  
Passive Internal Bus Termination  
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2 X 2 SCSI MATRIX SWITCH  
Low-Voltage Differential (LVD) SCSI (SC120A-R2 Only)  
Maximum Data Rate (8-bit Narrow): 40 MBps for Ultra2 SCSI (narrow transfers  
aren’t officially supported in the Ultra160 SCSI standard)  
Maximum Data Rate (16-bit Wide): 160 MBps  
Maximum Port Cable Length: 25 meters (82 ft.)  
Internal Terminator Impedance: 105 ohms  
Terminator Disconnect Capacitance: 3 pF  
Active Internal Bus Termination  
Serial Interface  
Baud Rate: 9600 or 19,200 bps  
Data Format: No parity, 8 bits, 1 stop bit (fixed)  
Maximum Cable Length: 15 meters (50 ft.)  
Rear-Panel Connectors: DB9  
LAN Port  
Protocol: TCP/IP  
Interface: Ethernet  
Data Rate: 10 MBps  
Rear-Panel Connector: RJ-45  
Agency Approvals  
®
UL , CUL, FCC Class A, CE  
8
 
CHAPTER 1: Specifications  
Physical  
Temperature: 32 F to 149°F (0 to 65°C)  
Humidity: Up to 90% relative humidity, noncondensing  
Power: 95 to 260 VAC 10% (25 watts)  
Size: 4.5"H x 11.3" W x 9.7"D (11.4 x 28.7 x 24.6 cm)  
Weight: 5.1 lb. (2.3 kg)  
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2 X 2 SCSI MATRIX SWITCH  
2. Introduction  
2.1 About the SCSI Switch  
The 2 x 2 SCSI Matrix Switch is a high-performance electronic crosspoint switch  
for use with the SCSI (Small Computer System Interface) bus. This product  
enables two independent SCSI buses to be selected and electrically connected in  
any combination via internal electronic switching circuits. The 2 x 2 SCSI Matrix  
Switch eliminates the need to swap and reconfigure SCSI cables and bus  
terminators when alternate system configurations are required.  
In conjunction with the 2 x 2 SCSI Switch dual RS-232 serial interface, a  
Graphical User Interface (GUI) allows the system administrator to remotely  
operate and control SCSI-port configuration and termination, report SCSI-bus  
activity, gather performance statistics, and set internal temperature points for  
alarm notification. Standard DOS or modem software can also be used to control  
the switch using simple ASCII control commands.  
Up to 32 SCSI Switches can be connected together and controlled by one serial  
port.  
2.2 Features  
• Ultra2, Ultra, and Fast SCSI compatible. SC120A-R2 is also Ultra160 SCSI  
(a.k.a. “Ultra3 SCSI”) compatible.  
• 80-MBps or (SC120A-R2 only) 160-MBps throughput (LVD).  
• Easy-to-use LCD panel.  
• Daisychain up to 32 switches.  
• Share up to 32 SCSI peripherals.  
• SC121A supports differential SCSI. SC120A-R2 supports single-ended or LVD  
SCSI.  
• Transparent electronic switching.  
• LAN port for TCP/IP-based network control, RS-232 ports for serial control.  
• Does not require SCSI-bus ID.  
• User-installable.  
10  
 
CHAPTER 2: Introduction  
2.2.1 LCD PANEL  
The 2 x 2 SCSI Matrix Switch features an easy-to-use, menu-driven LCD panel with  
soft-touch MENU, ENTER, and directional keys. The LCD is lighted, which allows  
for easy viewing and operation.  
2.2.2 FRONT-PANEL CONTROLS  
• Set and configure SCSI ports.  
• Set termination.  
• Set switch number.  
• View power-supply status.  
• View internal temperature.  
• Set internal-temperature alarm.  
• Set serial-port configuration.  
• Display SCSI-bus busy status.  
• Display port configuration.  
2.3 Technical Description  
2.3.1 AVAILABLE SCSI SWITCH INTERFACES  
The 2 x 2 SCSI Matrix Switch is available in the following configurations:  
• Single-ended/LVD interface (SC120A-R2)  
• Differential interface (SC121A)  
NOTE  
Make sure that the SCSI Switch you’re installing is used with the  
appropriate interface. Single-ended/LVD and differential SCSI devices  
cannot be installed on the same switch unless a SCSI differential  
converter is used.  
11  
 
2 X 2 SCSI MATRIX SWITCH  
2.3.2 GENERAL HARDWARE DESCRIPTION  
The 2 x 2 SCSI Matrix Switch’s rear panel identifies each of the independent SCSI  
ports. SCSI ports A and B have two daisychained connectors per port and SCSI  
ports 1 and 2 have single connectors for installation of SCSI devices. You can install  
the SCSI Switch at any point on the SCSI bus.  
Each port has internal termination that can be turned on or off from the LCD  
panel. External “terminator power” (TERMPWR) for devices and terminators are  
provided by internal resettable fuses.  
The SCSI Switch does not require a device ID and is completely transparent to  
all computers and peripherals on the SCSI bus. No additional software is needed  
for installation and operation. A universal switching power supply automatically  
adapts to input voltages between 95 VAC and 260 VAC.  
2.3.3 ULTRA2 SCSI COMPATIBILITY  
The SCSI Switch supports Ultra2 SCSI, 80-MBps (wide) SCSI host adapters,  
computers, and peripherals in asynchronous and synchronous mode. (SC120A-R2  
also supports Ultra160 SCSI, 160-MBps devices.) The SCSI Switch conforms to  
ANSI X3.131 and X3T9.2 specifications for single-ended devices. Disconnect and  
reselect functions are fully supported to ensure complete SCSI compatibility.  
2.3.4 SCSI SWITCH INSTALLATION  
Ports A and B are fully bidirectional to ports 1 and 2 (see Figures 2-1 through 2-3).  
You determine where to connect computers, host adapters, and peripherals. In  
general, if daisychained ports are required for connection to external peripherals,  
use ports A or B.  
The LCD panel is used to select port connections and enable or disable each  
internal SCSI port terminator. Refer to Chapter 4 for complete instructions on  
operating the LCD keypad.  
You can selectively enable or disable any internal terminator to meet system  
configurations and requirements.  
NOTES  
1. For proper operation of any SCSI bus, there must not be a “hanging”  
line or cable. Termination should be enabled on active SCSI ports that  
are not connected through to another port.  
2. Connections can be made to either connector on the appropriate port.  
3. In Figures 2-1 and 2-3, “Term” shows where terminators should be  
installed.  
12  
 
CHAPTER 2: Introduction  
SCSI Switch Ports  
Figure 2-1. SC121A block diagram.  
Figure 2-2. SC120A-R2 block diagram.  
13  
 
2 X 2 SCSI MATRIX SWITCH  
SCSI Switch (SC120A-R2)  
Figure 2-3. Typical switch installation.  
14  
 
CHAPTER 3: Installation  
3. Installation  
3.1 What’s Included  
• (1) 2 x 2 SCSI Matrix Switch  
• (1) AC power cord  
• (1) 10-ft. (3-m) DB9-male-to-DB9-female RS-232 cable  
• (1) DB9-male-to-DB25-female RS-232 adapter  
• (1) SCSI Matrix Switch control software CD-ROM  
• This users’ manual  
If anything is missing or damaged, call Black Box at 724-746-5500.  
3.2 AC Line Voltage  
You can connect the SCSI Switch to any AC input voltage between 95 and 260 volts.  
Unless otherwise specified, the switch will be shipped with a 110-volt power cord  
for use in the USA. For a power cord that will work in your country (outside the  
USA), call Black Box Technical Support.  
3.3 Switch Placement  
Place the SCSI Switch in a convenient location near the host computer or  
peripherals. Keep SCSI cable lengths short to provide the best performance and  
reliability. Make sure that the dual fans and ventilation slots on the sides of the  
switch receive adequate airflow. Do not place the switch on or near any devices that  
generate excessive heat.  
3.4 Power Equipment Off  
Power off all equipment and peripherals connected to the SCSI interface before  
installing cables or terminators.  
15  
 
2 X 2 SCSI MATRIX SWITCH  
3.5 SCSI Interface Cabling  
Both versions of the 2 x 2 SCSI Matrix Switch have 68-pin high-density connectors.  
Single-ended devices can have cable lengths up to 20 ft. (6 m). Differential or low-  
voltage differential (LVD) devices can be connected with up to 82 ft. (25 m) of  
cable.  
Connect the host adapter or peripheral to the rear-panel connector using a  
proper SCSI cable. Section 6.1 describes standard SCSI-interface requirements.  
When you connect devices to ports A and B, use one of the port connectors, not  
both.  
NOTE  
Do not intermix single-ended/LVD and differential devices on any SCSI  
chain unless a SCSI differential converter is used to convert from one  
bus type to the other.  
Figure 3-1. The SCSI Switch’s rear panel.  
3.6 RS-232 Serial Port Cabling  
The SCSI Switches have a DB9 female RS-232 serial port on their rear panel,  
pinned so that you can use a straight-through-pinned DB9 male-to-female serial  
cable (such as the one provided with the SCSI Switch) to connect it to the DB9  
male serial ports on a PC. Pins 1, 2, 3, 5, and 6 (CD, TD, RD, SGND, and DSR  
respectively) are functional on the SCSI Switch’s RS-232 port; Pins 4 and 8 (DTR  
and CTS) are tied together; and Pins 7 and 9 (RTS and RI) have no function.  
3.7 Ethernet LAN Port Cabling  
The SCSI Switches have an RJ-45 female 10BASE-T Ethernet port on their rear  
panel. Use a standard straight-through-pinned twisted-pair cable (CAT5 or higher)  
to connect this port to an Ethernet hub, switch, or router. To connect this port  
directly to a 10BASE-T port on a computer, you’ll need to use a cross-pinned cable.  
16  
 
CHAPTER 4: Operator Controls and Indicators  
4. Operator Controls and  
Indicators  
4.1 AC Power Switch  
The AC power switch is located on the SCSI Switch’s rear panel. Move it to the “|”  
position to turn on the switch.  
NOTE  
Always turn on the SCSI Switch before powering SCSI devices and  
computers. This will ensure that devices are found when the system  
boots up.  
4.2 LCD Display, Keypad, and Indicators  
4.2.1 LCD DISPLAY  
The LCD display shows the selection parameters available.  
SET PORTS  
>
SET TERMINATION  
DISPLAY PORTS  
DISPLAY ACTIVITY  
DISPLAY POWER TEMP  
FRONT PANEL LOCK  
SET SERIAL PORTS  
SET SWITCH NUMBER  
>
>
SET TEMP LIMIT  
DISPLAY VERSION  
Figure 4-1. The LCD display’s main menu.  
17  
 
2 X 2 SCSI MATRIX SWITCH  
4.2.2 KEYPAD  
Use the keypad to select menu and setup parameters for the SCSI Switch.  
• MENU: Returns to the SCSI Switch setup and configuration menu.  
• ENTER: Selects the highlighted setup parameter.  
• UP, DOWN, RIGHT, LEFT Arrows: Scrolls the cursor to enable menu  
selection.  
4.2.3 INDICATORS  
The indicators provide SCSI Switch status information.  
• POWER: Indicates that the SCSI Switch is powered.  
• BUSY: Indicates that there is SCSI activity on one or more SCSI ports.  
• ALARM: A visual and audible alarm indicates a failure of an internal power  
supply or that the SCSI Switch has exceeded the set temperature limit.  
NOTE  
To disable the audible alarm, press the front-panel MENU key. The  
ALARM light will remain lit until the condition is corrected.  
4.3 LCD Display Control Menus  
SET PORTS  
SET PORTS  
1
*
2
*
A
B
|
|
|
|
|
|
SET TERMINATION  
SET TERMINATION  
A *  
|
|
B
|
1
|
2
|
18  
 
CHAPTER 4: Operator Controls and Indicators  
DISPLAY PORTS  
DISPLAY PORTS  
| A 1 | A 2 |  
| B 1 | B 2 |  
SET SERIAL PORTS  
SET SERIAL PORTS  
COM 1  
COM 2  
DAISYCHAIN Y *  
9600 *  
9600 *  
19200  
19200  
N
SET SWITCH NUMBER  
SET SWITCH NUMBER  
01  
USE UP/DOWN KEYS  
DISPLAY POWER, TEMPERATURE  
DISPLAY POWER, TEMP  
PWR SUPPLY GOOD  
+25.5°C  
19  
 
2 X 2 SCSI MATRIX SWITCH  
SET TEMP LIMIT  
SET TEMP LIMIT  
MAX +40°C  
CURRENT TEMP +26.0°C  
DISPLAY BUS ACTIVITY  
DISPLAY ACTIVITY  
A
B
1
2
FRONT PANEL LOCK  
FRONT PANEL UNLOCKED  
ENTER PASSWORD  
TO LOCK 0 0 0 0  
DISPLAY VERSION  
BLACK BOX  
SC121A  
x
S/N 2 1 0 0 3 0 3  
H V D V E R 2 1 1 2 1 2 4 L A N  
In the DISPLAY VERSION panel:  
• “HVD,” “LVD,” or “SE” at bottom left indicates the current SCSI-bus interface  
mode.  
• “x” at top right indicates that the serial ports are locked.  
• “LAN” at bottom right indicates that the LAN port is active.  
20  
 
CHAPTER 4: Operator Controls and Indicators  
4.4 SCSI Switch Port Configuration  
The SCSI Switch has an internal memory device that retains the current  
configuration and setup information. Switch port, termination, serial port, and  
control parameters are saved as they are entered on the front panel.  
4.5 SCSI Switch Default Configuration  
The SCSI Switch default configuration as shipped from the factory is defined  
below.  
PORTS: A1, B2  
TERMINATION: SC121A: All Off; SC120A-R2: A, B On/1, 2, Off  
SERIAL PORTS: 9600 bps  
SWITCH NUMBER: 01  
TEMPERATURE ALARM: 40° Celsius (104˚F)  
FRONT PANEL: Unlocked, password 0000  
21  
 
2 X 2 SCSI MATRIX SWITCH  
5. Configuration and Operation  
5.1 SCSI Cable Interface Requirements  
The 2 x 2 SCSI Matrix Switch can be installed at any point on the SCSI bus. Always  
use high-quality cables for optimum computer performance and reliability.  
The SC121A differential switch contains 68-pin high-density connectors for up  
to 80-MB-per-second wide Ultra SCSI and Ultra2 SCSI computers and peripherals.  
The maximum cable distance should not exceed 82 ft. (25 m).  
The SC120A-R2 single-ended/low-voltage differential switch contains 68-pin  
high-density connectors for up to 160-MB-per-second wide Ultra SCSI, Ultra2 SCSI,  
and Ultra160 SCSI computers and peripherals:  
• Low-Voltage Differential (LVD):  
When operating with LVD devices, the SC120A-R2 supports 160-MBps wide  
Ultra160 SCSI computers and peripherals. The maximum cable distance for  
LVD should not exceed 82 ft. (25 m) total length.  
• Single-Ended (SE):  
When operating with SE devices, the SC120A-R2 supports 40-MBps wide Ultra  
SCSI computers and peripherals. The maximum cable distance for SE should  
not exceed 20 ft. (6 m) total length.  
Black Box offers standard and custom SCSI cables for connecting the SCSI  
Switch to host devices and peripherals. Call Black Box Technical Support for  
details.  
5.2 Internal Terminator Selection  
The SCSI Switch contains internal SCSI-bus terminators for each port.  
Termination is required at both ends of a SCSI bus for proper operation. Each  
port can have its internal terminator enabled or disabled from the front-panel  
display and keypad.  
Refer to Figure 5-4 to select internal termination.  
NOTE  
Data errors will result if more than two sets of terminators are installed  
on any SCSI bus (see Figures 2-1 and 2-2).  
22  
 
CHAPTER 5: Configuration and Operation  
SC120A-R2 TERMINATION CONFIGURATION  
Internal termination on Logic Component is always on by default and is not  
settable at the point of the logic components (see Figure 5-1). To ensure proper  
termination when configuring the switch termination, always have the termination  
enabled at the specified alphanumeric port and the termination disabled at the  
specified numeric port.  
Example:  
Host adapter is connected to port 1 (port 1 termination disabled) target device  
connected to port A (port A termination enabled), with port A1 enabled through  
the switch (see Figure 5-1).  
Figure 5-1. Termination configuration.  
23  
 
2 X 2 SCSI MATRIX SWITCH  
Figure 5-2. SC120A-R2 termination example 1.  
Figure 5-3. SC120A-R2 termination example 2.  
24  
 
CHAPTER 5: Configuration and Operation  
5.3 Selecting Internal Terminator Power  
On-board SCSI Switch terminators can be powered by internal 5-volt power or  
externally from SCSI-bus “terminator power” (TERMPWR).  
1
Internal 5V  
E13, E14, E19, E20  
2
3
or  
E15, E16, E21, E22  
External  
Terminator  
Power  
Figure 5-4. Internal terminator-power jumpers.  
Table 5-1. Jumper settings for internal termination.  
SC120A-R2  
SC121A  
E14-Port A  
E20-Port 1  
E15-Port A  
E21-Port 1  
E13-Port B  
E19-Port 2  
E16-Port B  
E22-Port 2  
NOTE  
The standard factory default connects internal terminators to internal  
5 volts.  
5.4 Selecting External Terminator Power  
The SCSI Switch can supply external terminator power via an internal resettable  
fuse. This fuse supplies 1 amp at 5 volts to the terminator-power (TERMPWR)  
signal. The SCSI Switch contains internal protection and will not be affected if  
other SCSI devices provide terminator power.  
E5, E6, E21, E22  
or  
E17–E20  
Figure 5-5. External terminator-power jumpers.  
NOTE  
Factory default is “Enabled” on all ports.  
25  
 
2 X 2 SCSI MATRIX SWITCH  
Table 5-2. Jumper settings for external termination.  
SC120A-R2 SC121A  
E6-Port A  
E22-Port 1  
E19-Port A  
E17-Port 1  
E5-Port B  
E21-Port 2  
E20-Port B  
E18-Port 2  
NOTE  
The standard factory default connects internal terminators to internal  
5 volts.  
5.5 Serial-Port Pinout  
The SCSI Switch contains two RS-232 serial ports, using DB9 female connectors;  
these allow external control of the switch. The connectors are compatible with  
standard RS-232 modem cables. The serial ports can be configured to operate  
separate communications ports or as daisychained ports.  
Daisychained mode allows one computer or terminal to communicate with  
multiple SCSI Switches.  
Table 5-3. Rear-panel RS-232 connector pinout.  
Signal  
Description  
DB9 Pin  
DB25 Pin  
DCD  
RXD  
TXD  
DTR  
GND  
DSR  
RTS  
CTS  
RI  
Data Carrier Detect  
Receive Data  
1
2
3
4
5
6
7
8
9
8
3
Transmit Data  
2
Data Terminal Ready  
Signal Ground  
20  
7
Data Set Ready  
Request to Send  
Clear to Send  
6
4
5
Ring Indicator  
22  
26  
 
CHAPTER 5: Configuration and Operation  
5.6 LAN/Serial-Port Commands  
You can use simple ASCII-character commands to control the SCSI Switch through  
either its LAN port (by opening a socket connection to port 3001) or one of its  
RS-232 serial ports. For serial control, set your computer’s serial port this way:  
a. Baud rate: 9600 (the switch’s factory default) or 19,200 bps.  
b. Data format: 8 data bits, 1 stop bit, no parity.  
c. Transmission mode: Half-duplex.  
So, for example, the DOS command to set a PC for serial communication with the  
switch would be MODE COMx 9600,N,8,1. Whether you’re using a LAN or serial  
connection, commands have the same syntax (format):  
a. Start sequence: ASCII <cr> (carriage return) followed by two slashes (“//”)  
b. Switch box number (you need this even if you have only one SCSI Switch):  
Box 1 - 7C hex (ASCII “|”)  
Box 2 - 7D hex (ASCII “}”)  
Box 3 - 7E hex(ASCII “~”)  
Box 4 - 7F hex (ASCII <del>)  
c. Port selection:  
Port A to port 1: “A1”, port A to port 2: “A2”;  
Port B to port 1: “B1”, port B to port 2: “B2”  
NOTE  
1. More than one port connection can be selected at the same time. For  
example, to select A1B2, transmit “A1B2.”  
2. “0” clears (disconnects) all numbered ports. For example, “A0” clears  
any numbered port connected to port A.  
d. Connection or disconnection type:  
ASCII “K” connects the specified ports and strictly adheres to SCSI rules.  
NOTE  
With “K,” if port A or B is not specified, no action will be taken on that  
port. If a connection is selected (for example, “A1”), that connection will  
be made, and the other numbered port will be disconnected from that  
lettered port. For example, entering “A2K” when port A is connected to  
port 1 will disconnect port A from port 1 and connect it to port 2.  
ASCII “N” connects the specified ports without breaking existing connections.  
ASCII “F” disconnects the specified ports.  
e. End sequence: ASCII <cr>  
So, for example, the complete command to connect the first SCSI Switch’s port A  
to port 2 and its port B to port 1 would look like this: <cr>//|A2B1K<cr>  
27  
 
2 X 2 SCSI MATRIX SWITCH  
Table 5-4. SCSI Switch commands.  
Command  
Cmd.  
Example  
Example Result or  
Response  
Char. Command String  
Select Port  
K
S
k
<cr>//|A1K<cr>  
<cr>//|S<cr>  
<cr>//|A1k<cr>  
<cr>//|s<cr>  
<cr>//|L<cr>  
<cr>//|U<cr>  
<cr>//|?<cr>  
A & 1 connected  
“//|a2b0K”  
Report Port Status  
Select Terminator  
Report Terminator Status  
Lock Front Panel  
Unlock Front Panel  
A & 1 terminated  
“//|ab1k”  
s
L
U
?
Panel locked  
Panel unlocked  
“//|text…”  
Report Model, S/N, and  
Date of Manufacture  
Report Alarm Status  
Report Temperature  
a
t
<cr>//|a<cr>  
<cr>//|t<cr>  
“//|a00”  
“//|t+23.5”  
(Celsius)  
Report Performance  
P
I
<cr>//|P<cr>  
<cr>//|I<cr>  
“//|PAABB1122”  
Report SCSI-Bus  
Inactivity  
“2C71” (hex, =  
1137.7 s or 19 m)  
Yank on SCSI Reset  
Line  
Y
<cr>//|AB1Y<cr>  
Ports A, B, and 1  
reset  
28  
 
CHAPTER 5: Configuration and Operation  
Table 5-4 (continued). SCSI Switch commands.  
Command  
Cmd.  
Example  
Example Result or  
Response  
Chars. Command String  
Enable/Disable Alarm  
Set Baud Rate  
OA  
OB  
OC  
OD  
OP  
<cr>//|OA0<cr>  
<cr>//|OB10<cr>  
<cr>//|OC0<cr>  
<cr>//|OD06<cr>  
<cr>//|OP3156<cr>  
Alarm enabled  
COM2 = 9600 bps  
Daisychain enabled  
Switch # = 6  
Set Serial Port Mode  
Set Switch Number  
Set Lock/Unlock  
Password  
Password = 3156  
Set Temperature Limit  
Report Revision  
OT  
R
<cr>//|OT45<cr>  
<cr>//|R<cr>  
Max. temp. = 45˚C  
“2024610”  
Lock Serial Ports  
OL  
<cr>//|OL3156<cr>  
//|OL1 pass  
//|OL0 fail  
Unlock Serial Ports  
OU  
OS  
<cr>//OU3156<cr>  
<cr>//|OS<cr>  
//|OU1 pass  
//|OU0 fail  
Report Serial Port  
Lock Status  
//|OS1 lock  
//|OS0 open  
29  
 
2 X 2 SCSI MATRIX SWITCH  
EXPANDED LIST OF COMMANDS  
a. Select SCSI Port Matrix:  
example command: <cr>//|A1B2K<cr>  
report: none  
NOTE  
K - Connects specified ports, but also breaks former connections  
and maintains proper termination as per SCSI rules.  
N - Connects specified ports without regard for former connections or  
termination.  
F - Disconnects the specified ports.  
b. Report SCSI Port Matrix Assignment Status  
example command: <cr>//|S<cr>  
example report: //|A1B2K  
c. Select SCSI Terminator Matrix  
example command: <cr>//|<AB12k><cr>  
report: none  
d. Report SCSI Terminator Status  
example command: <cr>//|s<cr>  
example report: //|AB12k  
e. Lock Front Panel  
example command: <cr>//|L<cr>  
report: none  
f. Unlock Front Panel  
example command: <cr>//|U<cr>  
report: none  
g. Report Model, Serial Number, and Date of Manufacture:  
example command: <cr>//|?<cr>  
example report: //|SC121A 21121150 10-15-02  
SC121A = model number  
21121150 = serial number  
10-15-02 = date of manufacture (mm-dd-yy)  
h. Report Alarm Status:  
example command: <cr>//|a<cr>  
report format: //|axy (x and y = ASCII 1 or 0)  
x: 0 = OK, 1= Overtemperature  
y: 0 = OK, 1= Power-supply failure  
30  
 
CHAPTER 5: Configuration and Operation  
i. Report Temperature:  
example command: <cr>//|t<cr>  
example report: //|t+19.5  
+19.5 = +19.5˚C, +67˚F  
j. Report SCSI-Bus Performance:  
example command: <cr>//|P<cr>  
report format: //|P<aabb1122><cr>  
For ports A, B, 1, and 2 respectively, aa, bb, 11, and 22 = ASCII  
representations of 8-bit hexadecimal values from 00 to FF, where  
00 represents 0% busy (completely idle) and FF represents 100% busy  
k. SCSI-Bus Inactivity to SCSI Report:  
example command: <cr>//|I<cr>  
report format: 1111 2222  
For ports 1 and 2 respectively, 1111 and 2222 = ASCII representations  
of 16-bit hexadecimal values that express the length of time in tenths of  
seconds that the port has been inactive (not transmitting or receiving  
data). For example, “0A73” = 0 x 4096 (163) + 10 x 256 (162) + 7 x 16 +  
3 tenths of seconds = 267.5 seconds = 4 minutes 27.5 seconds.  
l. Yank on SCSI Reset line:  
example command: <cr>//|B2Y<cr>  
report: none  
m. Enable/Disable Audible Alarm:  
example command: <cr>//|OAx<cr> [x = ASCII 1 or 0]  
x: 0 = enable alarm, 1 = disable alarm  
report: none  
n. Set Serial-Port Baud Rate:  
example command: <cr>//|OBxy<cr> [x and y = ASCII 1 or 0]  
x: 0 = COM1, 1 = COM2  
y: 0 = 9600 bps, 1 = 19,200 bps  
report: none  
o. Set Mode of Serial (Comm) Port for RS-232 Port 2:  
example command: <cr>//|OCx<cr> [x = ASCII 1 or 0]  
x: 0 = use Port 2 for daisychaining, 1 = use Port 2 as a second serial port  
report: none  
Note: This command has no effect if the LAN port is enabled, which  
disables RS-232 Port 2.  
31  
 
2 X 2 SCSI MATRIX SWITCH  
p. Set Switch (Device) Number:  
example command: <cr>//|ODxx<cr>  
xx = ASCII representation of decimal value from 01 through 32  
report: none  
q. Set “Lock/Unlock Front Panel” Password:  
example command: <cr>//|OPxxxx<cr>  
xxxx: ASCII 4-digit decimal number from 0000 to 9999  
report: none  
r. Set Temperature Limit:  
example command: <cr>//|OT<cr>  
xx: ASCII 2-digit decimal number from 15 to 55 (degrees C)  
report: none  
s. Report Revision of SCSI Switch’s Firmware:  
example command: <cr>//|R<cr>  
example report: 2059722  
t. Lock Serial Ports:  
example command: <cr>//|OLxxxx<cr>  
xxxx: password set with OP command (ASCII 4-digit decimal number  
from 0000 to 9999)  
example report: “//|OL1 pass” if password entered correctly, “//|OL0 fail”  
otherwise  
u. Unlock Serial Ports:  
example command: <cr>//|OUxxxx<cr>  
xxxx: password set with OP command (ASCII 4-digit decimal number  
from 0000 to 9999)  
example report: “//|OU1 pass” if password entered correctly,  
“//|OU0 fail” otherwise  
v. Report Serial-Port Lock Status:  
example command: <cr>//|OS<cr>  
example report: “//|OS1 lock” if the serial ports are locked,  
“//|OS0 open” otherwise  
32  
 
CHAPTER 5: Configuration and Operation  
5.7 ASCII Character Reference for SCSI Switch Box Selection  
Switch #  
ASCII  
1
|
2
}
3
~
4
5
`
6
a
7
b
8
c
<DEL>  
Switch #  
ASCII  
9
d
10  
e
11  
f
12  
g
13  
h
14  
i
15  
j
16  
k
Switch #  
ASCII  
17  
l
18  
m
19  
n
20  
o
21  
p
22  
q
23  
r
24  
s
Switch #  
ASCII  
25  
t
26  
u
27  
v
28  
w
29  
x
30  
y
31  
z
32  
{
5.8 Graphical User Interface (GUI)  
Your SCSI Switch is supplied with control software that is compatible with most  
®
®
recent Microsoft Windows operating systems to allow remote control of the  
switch. Follow instructions on the included CD-ROM to install the software.  
Figure 5-6. Screen shot of GUI control panel.  
33  
 
2 X 2 SCSI MATRIX SWITCH  
5.9 Connecting Multiple SCSI Switches  
Up to 32 SCSI Switches can be controlled by a single RS-232 serial interface. To  
operate in this configuration, set the serial ports to operate in daisychained mode.  
In Figure 5-7, “1” is RS-232 port 1 on each switch and “2” is RS-232 port 2.  
Computer  
RS-232  
2
2
1
1
2
1
1
SCSI Switch  
Box 1  
SCSI Switch  
Box 2  
SCSI Switch  
Box 4  
SCSI Switch  
Box 3  
Figure 5-7. Multiple SCSI Switch configuration.  
5.10 Typical Application  
Figure 5-8 shows a sample application for the SCSI Switch. Many other  
configurations are possible.  
Ethernet  
10BASE-T  
LAN  
connection  
for LAN-  
based  
switch  
control  
Server  
Server  
SCSI  
Switch  
Tape Drive  
Tape Drive  
RAID  
Figure 5-8. Sample application.  
34  
 
CHAPTER 5: Configuration and Operation  
5.11 Network Control of SCSI Switch  
The 2 x 2 SCSI Matrix Switch may be controlled over a TCP/IP network through  
its LAN port.  
5.11.1 LAN-PORT CONFIGURATION  
You can remotely control the SCSI Switch through a standard 10-Mbps Ethernet  
connection running TCP/IP. In the SCSI Switch’s factory-default setting, the LAN  
port will be enabled and the RS-232 COM2 port (which shares the same circuitry  
and is most often used for daisychaining SCSI Switches) will be disabled. If you  
want to daisychain SCSI Switches, you will need to disable the LAN port and enable  
the COM2 port. To do this, scroll through the control menus in the switch’s front-  
panel LCD (see Section 4.3) until you reach the SET SERIAL PORTS menu. Move  
the cursor to the DAISY CHAIN option and press ENTER on the switch’s keypad to  
change the setting from N to Y.  
35  
 
2 X 2 SCSI MATRIX SWITCH  
5.11.2 APCONCFG UTILITY  
The apconcfg.exe utility is used to configure the TCP/IP address. This utility is  
provided on the included CD-ROM. You can reconfigure the IP address by using  
the IP Configuration Utility. Run apconcfg.exe from the CD-ROM provided with  
your 2 x 2 SCSI Matrix Switch. A “Configure Network Switch” window will appear.  
Enter the new IP address and switch MAC address in the appropriate fields. The  
MAC address can be found on a label located on the bottom of the switch. You can  
search for the IP address by clicking the search button in the “Configure Network  
Switch.” This will bring up a “Search for Network Switches” window. Enter a  
beginning IP address, an ending IP address, and click Search.  
Command strings to control the SCSI Switch may be manually entered through  
certain versions of HyperTerminal to support connections to IP addresses through  
the LAN.  
NOTE  
You will need to specify port #3001 when establishing the connection.  
36  
 
CHAPTER 5: Configuration and Operation  
5.11.3 APCONCMD UTILITY  
The apconcmd.exe utility enables the user to set switch parameters through the  
LAN port. This utility is located on the CD-ROM provided with your SCSI Switch.  
To change switch settings and termination for an SCSI Switch, run (at a DOS  
prompt) APCONCMD.EXE from the CD-ROM.  
Usage:  
apconcmd [/?] [/i<IP address>] [/c<COM port>] [/b<baud rate>]  
[/n<Switch number>] [/h<holdoff>] [/x] [/t<termination>]  
[/s<Switch settings>] [/w<command>] [/r<command>]  
Where:  
/? = this message.  
/i <IP address> = The IP address of the network-enabled SCSI Switch.  
/c <COM port> = The number of the COM port to address (1 to 8; default = 1).  
/b <baud rate> = The baud rate of the COM port (2400, 9600, or 19200 [bps];  
default = 9600).  
/n <Switch number> = The number of the SCSI Switch to change (1 to 32;  
default = 1).  
/h <holdoff> = SCSI-bus holdoff, in seconds. The SCSI Switch will not change  
the switch settings on a bus until there has been no activity for the specified  
number of seconds. Valid range is 0 to 25 seconds.  
/x = Ignore SCSI-bus activity. Switch settings will be changed immediately.  
/t <termination> = Termination can be turned on (“N”) or off (“F”) for each  
port (A, B, 1, or 2). For example, “A2NB1F” activates termination for ports A  
and 2, and it deactivates termination on ports B and 1. Termination on any of  
the switch’s ports that aren’t specified in the command will not be affected.  
/s<Switch settings> = The settings to be changed. For example, “A1B2NB1A2F”  
connects ports A and 1 and B and 2 and disconnects ports B from 1 and A  
from 2. Switch settings on any of the switch’s ports that aren’t specified in the  
command will not be affected.  
/w<command> = <command> is sent to the switch with no parsing. Any  
response from the switch is ignored.  
/r<command> = <command> is sent to the switch with no parsing. Any response  
from the switch is displayed on the console’s error output.  
37  
 
2 X 2 SCSI MATRIX SWITCH  
6. SCSI Technical Information  
6.1 SCSI Basics  
6.1.1 SCSI-1  
The original specification supports data transfers up to 5 MBps on an 8-bit wide  
parallel data bus. SCSI-1 standards had some incompatibility problems between  
host adapters and peripheral devices. The need to improve compatibility, increase  
transfer rates, and add other features for better performance required a review of  
the specifications.  
6.1.2 SCSI-2  
Improved compatibility and higher transfer rates were provided in this  
enhancement. The addition of “Wide SCSI” permits 16 or 32 bits to be transferred  
in parallel, the latter requiring two cables. In combination with the “Fast SCSI”  
option, synchronous data transfers up to 10 MBps for 8-bit, 20 MBps for 16-bit, and  
40 MBps for 32-bit buses were achieved.  
6.1.3 SCSI-3  
The most significant additions include the ability to address up to 32 devices, a  
16-bit single-cable data bus, and serial SCSI protocol. The SCSI-3 standard has  
been split into several subdocuments, including the SCSI Parallel Interface (SPI),  
which is based on a layered protocol, and the SCSI Interlocked Protocol (SIP), a  
software link protocol.  
6.1.4 SIGNAL WIRING  
The signal wiring used in a SCSI bus has an impact on bus performance. The two  
wiring techniques generally used for SCSI are single-ended and differential. With  
single-ended wiring, a single wire carries the signal from initiator to target. Single-  
ended circuitry is not noise resistant and is generally limited to about 6 meters  
(20 ft.) at data transfer speeds of 10 MB per second.  
Differential wiring uses two wires for each signal and offers exceptional noise  
resistance because it does not rely on a common ground. This allows cables up to  
25 meters (82 ft.) and reliable operation at 10 MB or more per second. Differential  
wiring and circuitry is more complex than single-ended and generally tends to be  
more expensive to implement.  
38  
 
CHAPTER 6: SCSI Technical Information  
6.1.5 COMMON PROBLEMS  
The majority of problems encountered with SCSI-bus installations are due to  
unbalanced or improper impedances on the SCSI-bus transmission cables caused  
by varying manufacturers’ peripheral devices. SCSI terminators compensate for  
these inherent impedance mismatches on a SCSI bus where peripheral devices  
such as hard drives, CD-ROM drives, scanners, or printers are used.  
6.1.6 PASSIVE TERMINATORS  
The most basic is a passive-resistance style terminator. This is usually supplied with  
peripherals and frequently does a poor job of balancing the impedance of the  
SCSI bus. Passive terminators are resistor networks that allow signal voltages to vary  
with the load and terminator power supplied, resulting in unstable signals from  
end to end on the bus and causing data errors. Passive terminators are no longer  
recommended by ANSI for designs.  
6.1.7 ACTIVE TERMINATORS  
Active terminators add a voltage regulator to the circuit to regulate signal voltages  
with varying loads and terminator power, allowing a consistent signal to be  
transmitted everywhere on the bus. This in turn compensates for the varying bus  
lengths and signal loads. All lines are terminated through 110-ohm resistors, which  
are applicable to all narrow and wide single-ended applications. Active termination  
is the minimum ANSI-recommended termination.  
6.2 SCSI Installation Tips  
Keep your SCSI chain short. Official SCSI specifications limit the length of a SCSI  
chain to no more that 6 m (20 ft.) for single-ended or 25 m (82 ft.) for  
differential. Practical experience says the shorter, the better. The maximum  
length you should allow between devices is 3 ft. (0.9 m).  
Never assign the same SCSI ID number to two devices residing on the same bus. SCSI  
uses these numbers as addresses to ensure that information goes to the correct  
location. Giving two devices the same address can result in lost information.  
Know that some SCSI-ID numbers may be reassigned. Internal boot hard drives are  
usually set to ID “0” while secondary hard drives are set to “1”. Motherboards  
or host adapters are generally set to ID “7”.  
Always terminate the first and last devices on the chain. Drives purchased specifically  
for internal use nearly always arrive with terminators installed. If in doubt, call  
the vendor you purchased the device from.  
39  
 
2 X 2 SCSI MATRIX SWITCH  
If the last device on the chain has two SCSI connectors, attach the cable to one and a  
terminator to the other. Otherwise, you’ll have an open connector that may cause  
noise on the SCSI chain.  
Always turn off the power to your computer and SCSI devices before swapping cables or  
moving devices around. SCSI cables contain sensitive data transmission lines and  
one or more live power wires.  
Turn on your SCSI devices before you turn on the computer. Some SCSI devices will  
not mount if they are not running when you power up your computer.  
Shutting down your computer first and then the attached SCSI devices allows  
your system to completely “flush” itself.  
6.3 SCSI Interface Signal Descriptions  
A total of 18 signals are required for the SCSI interface. These signals are described  
as follows:  
BSY (BUSY): An “OR-tied” signal indicating that the bus is being used.  
SEL (SELECT): An “OR-tied” signal used either by an initiator to select a  
target or by a target to reselect an initiator.  
C/D (CONTROL/DATA): A signal driven by a target that indicates whether  
Control or Data information is on the data bus. True indicates Control.  
I/O (INPUT/OUTPUT): A signal driven by a target that controls the  
direction of data movement on the data bus with respect to an initiator. True  
indicates input to the initiator. This signal is also used to distinguish between  
Selection and Reselection phases.  
MSG (MESSAGE): A signal driven by a target during the Message phase.  
REQ (REQUEST): A signal driven by a target to indicate a request for a  
REQ/ACK data-transfer handshake.  
ACK (ACKNOWLEDGE): A signal driven by an initiator to indicate an  
acknowledgment for a REQ/ACK data-transfer handshake.  
ATN (ATTENTION): A signal driven by an initiator to indicate the Attention  
condition.  
RST (RESET): An “OR-tied” signal that indicates the Reset condition.  
40  
 
CHAPTER 6: SCSI Technical Information  
DB0 through DB15, P, P1 (DATA BUS): Sixteen data-bit signals and two parity-  
bit signals that together form a data bus. DB15 is the most significant bit and  
has the highest priority during the Arbitration phase. Bit number, significance,  
and priority decrease downward to DB0. A data bit is defined as a one when  
the signal value is true and as a zero when the signal value is false. Data parity  
DBP and DBP1 shall be odd.  
Table 6-1. SCSI connector assignments for  
single-ended (SE) 16-bit SCSI (wide).  
Signal Name  
Ground  
Ground  
Ground  
Ground  
Ground  
Ground  
Ground  
Ground  
Ground  
Ground  
Ground  
Ground  
Ground  
Ground  
Pin Number  
Signal Name  
-DB12  
-DB13  
-DB14  
-DB15  
-DBP1  
-DB0  
Pin Number  
1
2
35  
36  
37  
38  
39  
40  
41  
42  
43  
44  
45  
46  
47  
48  
3
4
5
6
7
-DB1  
8
-DB2  
9
-DB3  
10  
11  
12  
13  
14  
-DB4  
-DB5  
-DB6  
-DB7  
-DBP  
41  
 
2 X 2 SCSI MATRIX SWITCH  
Table 6-1 (continued). SCSI connector assignments for  
single-ended (SE) 16-bit SCSI (wide).  
Signal Name  
Ground  
Pin Number  
Signal Name  
Ground  
Ground  
TERMPWR  
TERMPWR  
Reserved  
Ground  
-ATN  
Pin Number  
15  
16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
27  
28  
29  
30  
31  
49  
50  
51  
52  
53  
54  
55  
56  
57  
58  
59  
60  
61  
62  
63  
64  
65  
Ground  
TERMPWR  
TERMPWR  
Reserved  
Ground  
Ground  
Ground  
Ground  
-BSY  
Ground  
Ground  
-ACK  
Ground  
-RST  
Ground  
-MSG  
Ground  
-SEL  
Ground  
-C/D  
Ground  
-REQ  
Ground  
-I/O  
Ground  
-DB8  
42  
 
CHAPTER 6: SCSI Technical Information  
Table 6-1 (continued). SCSI connector assignments for  
single-ended (SE) 16-bit SCSI (wide).  
Signal Name  
Ground  
Pin Number  
Signal Name  
-DB9  
Pin Number  
32  
33  
34  
66  
67  
68  
Ground  
-DB10  
Ground  
-DB11  
Table 6-2. SCSI connector assignments for  
differential 16-bit SCSI (wide).  
Signal Name  
+DB(12)  
+DB(13)  
+DB(14)  
+DB(15)  
+DB(P1)  
Ground  
+DB(0)  
Pin Number  
Signal Name  
-DB(12)  
-DB(13)  
-DB(14)  
-DB(15)  
-DB(P1)  
Ground  
-DB(0)  
Pin Number  
1
2
35  
36  
37  
38  
39  
40  
41  
42  
43  
44  
45  
3
4
5
6
7
+DB(1)  
8
-DB(1)  
+DB(2)  
9
-DB(2)  
+DB(3)  
10  
11  
-DB(3)  
+DB(4)  
-DB(4)  
43  
 
2 X 2 SCSI MATRIX SWITCH  
Table 6-2 (continued). SCSI connector assignments for  
differential 16-bit SCSI (wide).  
Signal Name  
+DB(5)  
+DB(6)  
+DB(7)  
+DB(P)  
DIFFSENS  
TERMPWR  
TERMPWR  
Reserved  
+ATN  
Pin Number  
Signal Name  
-DB(5)  
-DB(6)  
-DB(7)  
-DB(P)  
Ground  
TERMPWR  
TERMPWR  
Reserved  
-ATN  
Pin Number  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
27  
28  
46  
47  
48  
49  
50  
51  
52  
53  
54  
55  
56  
57  
58  
59  
60  
61  
62  
Ground  
+BSY  
Ground  
-BSY  
+ACK  
-ACK  
+RST  
-RST  
+MSG  
-MSG  
+SEL  
-SEL  
+C/D  
-C/D  
+REQ  
-REQ  
44  
 
CHAPTER 6: SCSI Technical Information  
Table 6-2 (continued). SCSI connector assignments for  
differential 16-bit SCSI (wide).  
Signal Name  
+I/O  
Pin Number  
Signal Name  
-I/O  
Pin Number  
29  
30  
31  
32  
33  
34  
63  
64  
65  
66  
67  
68  
Ground  
+DB(8)  
+DB(9)  
+DB(10)  
+DB(11)  
Ground  
-DB(8)  
-DB(9)  
-DB(10)  
-DB(11)  
Table 6-3. SCSI connector assignments for  
low-voltage differential (LVD) 16-bit SCSI (wide).  
Signal Name  
+DB(12)  
+DB(13)  
+DB(14)  
+DB(15)  
+DB(P1)  
+DB(0)  
Pin Number  
Signal Name  
-DB(12)  
-DB(13)  
-DB(14)  
-DB(15)  
-DB(P1)  
-DB(0)  
Pin Number  
1
2
3
4
5
6
7
8
9
35  
36  
37  
38  
39  
40  
41  
42  
43  
+DB(1)  
-DB(1)  
+DB(2)  
-DB(2)  
+DB(3)  
-DB(3)  
45  
 
2 X 2 SCSI MATRIX SWITCH  
Table 6-3 (continued). SCSI connector assignments for  
low-voltage differential (LVD) 16-bit SCSI (wide).  
Signal Name  
+DB(4)  
Pin Number  
Signal Name  
-DB(4)  
Pin Number  
10  
11  
12  
13  
14  
15  
16  
17  
18  
19  
20  
21  
22  
23  
24  
25  
26  
44  
45  
46  
47  
48  
49  
50  
51  
52  
53  
54  
55  
56  
57  
58  
59  
60  
+DB(5)  
-DB(5)  
+DB(6)  
-DB(6)  
+DB(7)  
-DB(7)  
+DB(P)  
Ground  
DIFFSENS  
TERMPWR  
TERMPWR  
Reserved  
Ground  
+ATN  
-DB(P)  
Ground  
Ground  
TERMPWR  
TERMPWR  
Reserved  
Ground  
-ATN  
Ground  
+BSY  
Ground  
-BSY  
+ACK  
-ACK  
+RST  
-RST  
+MSG  
-MSG  
46  
 
CHAPTER 6: SCSI Technical Information  
Table 6-3 (continued). SCSI connector assignments for  
low-voltage differential (LVD) 16-bit SCSI (wide).  
Signal Name  
+SEL  
Pin Number  
Signal Name  
-SEL  
Pin Number  
27  
28  
29  
30  
31  
32  
33  
34  
61  
62  
63  
64  
65  
66  
67  
68  
+C/D  
-C/D  
+REQ  
-REQ  
+I/O  
-I/O  
+DB(8)  
+DB(9)  
+DB(10)  
+DB(11)  
-DB(8)  
-DB(9)  
-DB(10)  
-DB(11)  
47  
 
2 X 2 SCSI MATRIX SWITCH  
Table 6-4. SCSI distance/device support.  
STA Term  
Maximum Bus Length (M)  
Maximum Devices  
SE  
HVD  
25  
25  
25  
25  
LVD  
25  
12  
25  
12  
SCSI-1  
6
8
8
Fast SCSI  
6
Fast Wide SCSI  
Ultra SCSI  
6
16  
8
1.5  
3
Ultra SCSI  
4
Wide Ultra SCSI  
Wide Ultra SCSI  
Wide Ultra SCSI  
Ultra2 SCSI  
25  
16  
8
1.5  
3
4
N/A  
N/A  
N/A  
N/A  
25  
12  
25  
12  
2
Ultra2 SCSI  
8
Wide Ultra2 SCSI  
Wide Ultra2 SCSI  
2
16  
48  
 
CHAPTER 6: SCSI Technical Information  
To access jumper options:  
Remove the four screws on the bottom of the unit. Then lift off the cover.  
Figure 6-1. SCSI Switch component placement.  
• Internal termination jumper block: E13, E14, E19, E20 on SC120A-R2 or  
E15, E16, E21, E22 on SC121A (see Section 5.3).  
49  
 
2 X 2 SCSI MATRIX SWITCH  
7. Troubleshooting  
7.1 Calling Black Box  
If you determine that your 2 x 2 SCSI Matrix Switch is malfunctioning, do not  
attempt to alter or repair the unit. It contains no user-serviceable parts. Contact Black  
Box at 724-746-5500.  
Before you do, make a record of the history of the problem. We will be able to  
provide more efficient and accurate assistance if you have a complete description,  
including:  
• the nature and duration of the problem;  
• when the problem occurs;  
• the components involved in the problem;  
• any particular application that, when used, appears to create the problem or  
make it worse; and  
• the results of any testing you’ve already done.  
7.2 Shipping and Packaging  
If you need to transport or ship your 2 x 2 SCSI Matrix Switch:  
• Package it carefully. We recommend that you use the original container.  
• If you are shipping the switch for repair, make sure you include everything that  
came in the original package. Before you ship, contact Black Box to get a  
Return Authorization (RA) number.  
50  
 
LEGAL INFORMATION  
DISCLAIMERS AND NOTICES  
The manufacturer specifically disclaims the implied warranties for this product of  
merchantability and fitness for a particular purpose. Some states and provinces do  
not allow limitations on how long an implied warranty lasts, so the above limitation  
or exclusion might not apply to you.  
In no event shall the manufacturer or its authorized representatives be liable for  
any lost profits or direct, indirect, special, incidental, or consequential damages,  
whether based on contract, tort, or any other legal theory.  
No part of this manual may be reproduced, copied, or translated without prior  
written approval of the manufacturer or its authorized representatives.  
The manufacturer and its authorized representatives reserve the right to revise  
this publication from time to time without being obliged to notify any person or  
organization of such revision. We have prepared this manual for use by customers  
as a guide for the proper installation, operation, and maintenance of this  
equipment. The illustrations, specifications, and other information contained in  
this document are the property of the manufacturer and its authorized  
representatives, and any unauthorized use or disclosure of this information is  
prohibited.  
The manufacturer and its authorized representatives make no warranty of any  
kind with regard to this manual. We shall not be liable for errors contained herein  
or for incidental consequential damages in connection with the furnishing,  
performance, or use of this material.  
51  
 
© Copyright 2002. Black Box Corporation. All rights reserved.  
1000 Park Drive  
Lawrence, PA 15055-1018  
724-746-5500  
Fax 724-746-0746  
 

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