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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 S

IGNAL

W

IRING

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.

Summary of Contents for SC120A-R2

Page 1: ...r 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 Web site www blackbox com E mail info blackbox com ...

Page 2: ...of this equipment in a residential area is likely to cause interference in which case the user at his own expense will be required to take whatever measures may be necessary to correct the interference Changes or modifications not expressly approved by the party responsible for compliance could void the user s authority to operate the equipment This digital apparatus does not exceed the Class A li...

Page 3: ... 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 co...

Page 4: ...ir 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 ...

Page 5: ...oration 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 ...

Page 6: ...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...

Page 7: ...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 ...

Page 8: ...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 Por...

Page 9: ... 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 4...

Page 10: ... 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 ...

Page 11: ...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...

Page 12: ...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 wit...

Page 13: ...nous 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...

Page 14: ...13 CHAPTER 2 Introduction Figure 2 1 SC121A block diagram Figure 2 2 SC120A R2 block diagram SCSI Switch Ports ...

Page 15: ...14 2 X 2 SCSI MATRIX SWITCH Figure 2 3 Typical switch installation SCSI Switch SC120A R2 ...

Page 16: ...h 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 t...

Page 17: ...s 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 respectivel...

Page 18: ...he 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 Figure 4 1 The LCD display s main menu SET TEMP LIMIT DISPLAY VERSION DISPLAY POWER TEMP FRONT PANEL LOCK SET SERIAL PORTS SET SWITCH NUMBER SET PORTS SET TERMINATI...

Page 19: ...ovide 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...

Page 20: ...ISPLAY PORTS SET SERIAL PORTS SET SWITCH NUMBER DISPLAY POWER TEMPERATURE DISPLAY POWER TEMP PWR SUPPLY GOOD 25 5 C SET SWITCH NUMBER 01 USE UP DOWN KEYS SET SERIAL PORTS COM 1 9600 19200 COM 2 9600 19200 DAISYCHAIN Y N DISPLAY PORTS A 1 A 2 B 1 B 2 ...

Page 21: ...ft 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 BLACK BOX SC121A 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 FRONT PANEL UNLOCKED ENTER PASSWORD TO LOCK 0 0 0 0 DISPLAY ACTIVITY A B 1 2 SET TEMP LIMIT MAX 40 C CURRENT TEMP 26 0 C x ...

Page 22: ... 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 ...

Page 23: ...upports 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 th...

Page 24: ...nsure 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 Termin...

Page 25: ...24 2 X 2 SCSI MATRIX SWITCH Figure 5 2 SC120A R2 termination example 1 Figure 5 3 SC120A R2 termination example 2 ...

Page 26: ... 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 terminat...

Page 27: ...ternal 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 Data Carrier Detect 1 8 RXD ...

Page 28: ...SCII 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 stric...

Page 29: ... A 1 terminated Report Terminator Status s cr s cr ab1k Lock Front Panel L cr L cr Panel locked Unlock Front Panel U cr U cr Panel unlocked Report Model S N and cr cr text Date of Manufacture Report Alarm Status a cr a cr a00 Report Temperature t cr t cr t 23 5 Celsius Report Performance P cr P cr PAABB1122 Report SCSI Bus I cr I cr 2C71 hex Inactivity 1137 7 s or 19 m Yank on SCSI Reset Y cr AB1Y...

Page 30: ...B10 cr COM2 9600 bps Set Serial Port Mode OC cr OC0 cr Daisychain enabled Set Switch Number OD cr OD06 cr Switch 6 Set Lock Unlock OP cr OP3156 cr Password 3156 Password Set Temperature Limit OT cr OT45 cr Max temp 45 C Report Revision R cr R cr 2024610 Lock Serial Ports OL cr OL3156 cr OL1 pass OL0 fail Unlock Serial Ports OU cr OU3156 cr OU1 pass OU0 fail Report Serial Port OS cr OS cr OS1 lock ...

Page 31: ...r 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 S...

Page 32: ...s 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 S...

Page 33: ...sion 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 ...

Page 34: ...17 18 19 20 21 22 23 24 ASCII l m n o p q r s Switch 25 26 27 28 29 30 31 32 ASCII t u v w x y z 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 pane...

Page 35: ...ort 1 on each switch and 2 is RS 232 port 2 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 Figure 5 8 Sample application Server Ethernet LAN Tape Drive Tape Drive RAID Server SCSI Switch 10BASE T connection for LAN based switch control Computer SCSI Switch Box 1 SCSI Switch Box ...

Page 36: ...ry 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 SERI...

Page 37: ...ess 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 ma...

Page 38: ...conds 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 termi...

Page 39: ...e 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 wirin...

Page 40: ...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...

Page 41: ...ollows 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 o...

Page 42: ... 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 Pin Number Signal Name Pin Number Ground 1 DB12 35 Ground 2 DB13 36 Ground 3 DB14 37 Ground 4 DB15 38 Ground 5 DBP1 39 Ground 6 DB0 40 Ground 7 DB1 41 Ground 8 DB2 4...

Page 43: ...gnal Name Pin Number Ground 15 Ground 49 Ground 16 Ground 50 TERMPWR 17 TERMPWR 51 TERMPWR 18 TERMPWR 52 Reserved 19 Reserved 53 Ground 20 Ground 54 Ground 21 ATN 55 Ground 22 Ground 56 Ground 23 BSY 57 Ground 24 ACK 58 Ground 25 RST 59 Ground 26 MSG 60 Ground 27 SEL 61 Ground 28 C D 62 Ground 29 REQ 63 Ground 30 I O 64 Ground 31 DB8 65 ...

Page 44: ...Pin Number Ground 32 DB9 66 Ground 33 DB10 67 Ground 34 DB11 68 Table 6 2 SCSI connector assignments for differential 16 bit SCSI wide Signal Name Pin Number Signal Name Pin Number DB 12 1 DB 12 35 DB 13 2 DB 13 36 DB 14 3 DB 14 37 DB 15 4 DB 15 38 DB P1 5 DB P1 39 Ground 6 Ground 40 DB 0 7 DB 0 41 DB 1 8 DB 1 42 DB 2 9 DB 2 43 DB 3 10 DB 3 44 DB 4 11 DB 4 45 ...

Page 45: ...e Pin Number Signal Name Pin Number DB 5 12 DB 5 46 DB 6 13 DB 6 47 DB 7 14 DB 7 48 DB P 15 DB P 49 DIFFSENS 16 Ground 50 TERMPWR 17 TERMPWR 51 TERMPWR 18 TERMPWR 52 Reserved 19 Reserved 53 ATN 20 ATN 54 Ground 21 Ground 55 BSY 22 BSY 56 ACK 23 ACK 57 RST 24 RST 58 MSG 25 MSG 59 SEL 26 SEL 60 C D 27 C D 61 REQ 28 REQ 62 ...

Page 46: ...9 I O 63 Ground 30 Ground 64 DB 8 31 DB 8 65 DB 9 32 DB 9 66 DB 10 33 DB 10 67 DB 11 34 DB 11 68 Table 6 3 SCSI connector assignments for low voltage differential LVD 16 bit SCSI wide Signal Name Pin Number Signal Name Pin Number DB 12 1 DB 12 35 DB 13 2 DB 13 36 DB 14 3 DB 14 37 DB 15 4 DB 15 38 DB P1 5 DB P1 39 DB 0 6 DB 0 40 DB 1 7 DB 1 41 DB 2 8 DB 2 42 DB 3 9 DB 3 43 ...

Page 47: ...me Pin Number Signal Name Pin Number DB 4 10 DB 4 44 DB 5 11 DB 5 45 DB 6 12 DB 6 46 DB 7 13 DB 7 47 DB P 14 DB P 48 Ground 15 Ground 49 DIFFSENS 16 Ground 50 TERMPWR 17 TERMPWR 51 TERMPWR 18 TERMPWR 52 Reserved 19 Reserved 53 Ground 20 Ground 54 ATN 21 ATN 55 Ground 22 Ground 56 BSY 23 BSY 57 ACK 24 ACK 58 RST 25 RST 59 MSG 26 MSG 60 ...

Page 48: ...ntinued SCSI connector assignments for low voltage differential LVD 16 bit SCSI wide Signal Name Pin Number Signal Name Pin Number SEL 27 SEL 61 C D 28 C D 62 REQ 29 REQ 63 I O 30 I O 64 DB 8 31 DB 8 65 DB 9 32 DB 9 66 DB 10 33 DB 10 67 DB 11 34 DB 11 68 ...

Page 49: ...gth M Maximum Devices SE HVD LVD SCSI 1 6 25 8 Fast SCSI 6 25 8 Fast Wide SCSI 6 25 16 Ultra SCSI 1 5 25 8 Ultra SCSI 3 4 Wide Ultra SCSI 25 16 Wide Ultra SCSI 1 5 8 Wide Ultra SCSI 3 4 Ultra2 SCSI N A 25 25 2 Ultra2 SCSI N A 12 12 8 Wide Ultra2 SCSI N A 25 25 2 Wide Ultra2 SCSI N A 12 12 16 ...

Page 50: ...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 ...

Page 51: ...scription 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 t...

Page 52: ...turer 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...

Page 53: ...1000 Park Drive Lawrence PA 15055 1018 724 746 5500 Fax 724 746 0746 Copyright 2002 Black Box Corporation All rights reserved ...

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