Black Box IC124A User manual

1000 Park Drive • Lawrence, PA 15055-1018 • 724-746-5500 • Fax [phone]
© Copyright 2000. Black Box Corporation. All rights reserved.

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INFORMATION
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Mail order: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: [email protected]
JULY 2000
IC124A
IC125A
IC152A
SCSI Differential Converters
BUS ACTIVE
SCSI Differential Converter
POWER

1
FCC AND DOC/MDC STATEMENTS
FEDERAL COMMUNICATIONS COMMISSION
AND
INDUSTRY CANADA
RADIO FREQUENCY INTERFERENCE STATEMENTS
This equipment generates, uses, and can radiate radio frequency energy and if not
installed and used properly, that is, in strict accordance with the manufacturer’s
instructions, may cause interference to radio communication. It has been tested
and found to comply with the limits for a Class A computing device in accordance
with the specifications in Subpart J of Part 15 of FCC rules, which are designed to
provide reasonable protection against such interference when the equipment is
operated in a commercial environment. Operation 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 limits for radio noise emission from digital
apparatus set out in the Radio Interference Regulation of Industry Canada.
Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites
applicables aux appareils numériques de la classe A prescrites dans le Règlement sur le
brouillage radioélectrique publié par Industrie Canada.

2
SCSI DIFFERENTIAL CONVERTERS
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.

3
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 objectos 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: Objectos 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.

4
SCSI DIFFERENTIAL CONVERTERS
TRADEMARKS USED IN THIS MANUAL
Centronics is a registered trademark of Centronics Corporation.
Any other trademarks mentioned in this manual are acknowledged to be the
property of the trademark owners.

5
CONTENTS
Contents
Chapter Page
1. Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.1 General Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3 Hardware Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3. Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.1 Unpacking Your Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3 Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.4 The Installation Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.1 The Front Panel and Its LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.2 System Function and Performance . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5. Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.1 Contacting Black Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.2 Shipping and Packaging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Appendix A: Connector Pinouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
A.1 Single-Ended Narrow SCSI (50-Pin Centronics) Ports (IC124A) . . 20
A.2 Differential Narrow SCSI (50-Pin High-Density) Ports (IC124A) . . 21
A.3 Single-Ended Wide SCSI (68-Pin High-Density) Ports (IC125A) . . 22
A.4 Differential Wide SCSI (68-Pin High-Density) Ports (IC125A) . . . . 23
Appendix B: SCSI Technical Information . . . . . . . . . . . . . . . . . . . . . . . . . 25
B.1 SCSI Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
B.2 SCSI Installation Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
B.3 SCSI Signal Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Appendix C: Internal Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
C.1 Opening the Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
C.2 Setting the Converter for 220-VAC Input Power . . . . . . . . . . . . . . 32
C.3 Setting the Single-Ended Port for External Termination . . . . . . . 32
C.4 Setting the Differential Port for External Termination . . . . . . . . . 32
C.5 Replacing Internal Terminators . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

6
SCSI DIFFERENTIAL CONVERTERS
Chapter Page
C.6 Removing or Replacing Fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
C.7 Closing the Converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

7
CHAPTER 1: Specifications
1. Specifications
Compliance — FCC Class A, DOC Class/MDC classe A
Standards — SCSI: ANSI X3.131 and X3T9.2
Interfaces — IC124A: Narrow SCSI;
IC125A: SE to HVD Wide SCSI;
IC152A: SE/LVD to HVD Wide SCSI
Compatibility — IC124A: SCSI-1 and Fast SCSI (SCSI-2);
IC125A: Fast SCSI (SCSI-2);
IC152A: SCSI-1, SCSI-2, SCSI-3, and Ultra-SCSI-2
Protocol — Synchronous or asynchronous
Maximum Data
Rate — IC124A: 10 megabytes per second;
IC125A: 20 megabytes per second;
IC152A: 80 megabytes per second
Maximum Signal
Slew — 5 ns
Maximum S.-E./Diff.
Conversion Delay — 30 ns
Maximum Total
Delay — Across SCSI bus extended to maximum distance
through Converter: ~210 ns
Maximum Distance — IC124A:
From single-ended port to most distant
attached device: 6 m (19.7 ft.) at 5 MBps or 3 m
(9.8 ft.) at 10 MBps;
From differential port to most distant attached
device: 25 m (82 ft.);
IC125A:
From single-ended port to most distant attached
device: 6 m (19.7 ft.) at 10 MBps or 3 m (9.8 ft.)
at 20 MBps;

8
SCSI DIFFERENTIAL CONVERTERS
Maximum Distance
(continued)— From differential port to most distant attached
device: 25 m (82 ft.);
IC152A:
From single-ended port to most distant attached
device: 6 m (19.7 ft.) at 40 MBps or 3m (9.8 ft.) at
80 MBps
From differential port to most distant attached
device: 25 m (82 ft.)
SCSI ID — None required
Termination — Single-ended port: Single-ended: Internal active or
external (user-selectable);
Differential port: Internal differential (can be
removed in favor of an external terminator)
Internal Terminator
Power — 1 amp to the single-ended port and/or the differential
port (user-selectable); internal resettable fuse will
provide 5 VDC at 1 amp
User Controls — (1) Rear-mounted ON/OFF rocker switch;
(3) Internal jumpers for termination and terminator
power
Indicator — (2) Front-mounted LEDs: Power, Bus Active
Connectors — All rear-mounted:
(1) IEC 320 male power inlet;
IC124A only:
(1) 50-pin Centronics female for single-ended
SCSI data;
(1) 50-pin high-density female for differential
SCSI data;
IC125A only:
(2) 68-pin high-density female for single-ended
and differential SCSI data
IC152A only:
(2) 68-pin high-density female for single-ended/low-voltage
differential and high-voltage differential SCSI data

9
CHAPTER 1: Specifications
Power — Through detachable power cord and internal power
supply:
Optimal Input: 110 VAC, 60 Hz, or 220 VAC,
50 Hz (user-selectable);
Input Range: 99 to 121 VAC or 198 to 242 VAC,
48 to 65 Hz;
Input Current Rating: 1.5 amps;
Consumption (all models): 15 watts
MTBF — 283,000 hours
Temperature
Tolerance — 32 to 131˚F (0 to 55˚C)
Humidity
Tolerance — 0 to 90% noncondensing
Size — 2.1"H x 6"W x 9.6"D (5.3 x 15.2 x 24.4 cm)
Weight — 2.5 lb. (1.1 kg)

10
SCSI DIFFERENTIAL CONVERTERS
2. Introduction
2.1 General Overview
The SCSI Differential Converter is a high-performance bus converter that
translates single-ended SCSI-bus signals into differential bus signals and vice versa.
Through these Converters, computers with single-ended host adapters can
communicate with differential peripherals, and computers with differential host
adapters can access single-ended peripherals.
The “narrow SCSI” Converter (product code IC124A) is fully compatible with
8-bit SCSI-1 and Fast SCSI (SCSI-2) applications; the “wide SCSI” Converters
(product code IC125A and IC152A) are fully compatible with 16-bit Fast SCSI
applications.
You can also use a pair of Converters to extend one single-ended SCSI bus:
Attaching a 6-m (19.7-ft.) single-ended bus to each Converter and running a 25-m
(82-ft.) differential cable between them would create a single single-ended SCSI
bus 37 m (121.4 ft.) long.
2.2 Features
• Differential (HVD) to single-ended (SE), single-ended to differential converter
• Low-voltage Differential (LVD) to Differential (HVD), Differential to Low
Voltage Differential converter
• Extend SCSI bus by up to 25 m (82 ft.).
• Compatible with SCSI-1, Fast SCSI (SCSI-2), and SCSI-3
• Supports Ultra/Ultra2 SCSI narrow and wide devices
• Asynchronous and synchronous compatible
• 10-, 20-, 40-, or 80-Megabyte-per-second (MBps) maximum data rate
• Compatible with synchronous and asynchronous applications
• Transparent to SCSI controllers and peripherals; require no SCSI IDs
• Units can be paired to extend a single-ended bus
• Internal bus termination (“active” single-ended termination)

11
CHAPTER 2: Introduction
• No additional software required
• User-installable
2.3 Hardware Description
The industry-standard SCSI (pronounced “scuzzy”) bus is a popular high-speed
medium used to interconnect micro-, mini-, and mainframe computers and high-
performance peripherals. However, it is subdivided into several mutually
incompatible specifications, such as “single-ended” (one-signal) vs. “differential”
(two-signal) SCSI and “narrow” (8-bit) vs. “wide” (16-bit) SCSI. The SCSI
Differential Converters help to overcome these incompatibilities: The narrow
model (product code IC124A) lets narrow single-ended equipment talk to narrow
differential equipment, and through one of the wide models (product code
IC125A), wide single-ended equipment can talk to wide differential equipment.
The other wide model (product code IC152A) lets wide single-ended/low-voltage
differential equipment communicate with wide high-voltage differential
equipment. The IC152A is also a 25-meter extender.
The Converters support a maximum SCSI data rate of 10 MBps (IC124A),
20 MBps (IC125A), or 80 MBps (IC152A) in asynchronous or synchronous mode.
All models support the “Fast SCSI” standard available in top-of-the-line computers
and peripherals. Proprietary switching enables the Converters to maintain
complete SCSI command functionality and remain transparent to the user.
The Converters conform to ANSI X3.131 and X3T9.2 specifications for device
termination. Disconnect and Reselect are fully supported to ensure complete SCSI
compatibility. And the Converters do not require SCSI device addresses (ID
numbers).
You can install a Converter at any point on the SCSI bus to provide single-
ended/differential conversion. This makes it possible to interconnect computers
with different types of SCSI host adapters in a communication link that
outperforms standard local area networks such as 10-Mbps Ethernet and 16-Mbps
Token Ring. You can also install a pair of Converters and up to 25 m (82 ft.) of
differential cabling to link two chains of one single-ended bus.
Three different SCSI Differential Converter applications are shown in Figure 2-1
on the next page.

12
SCSI DIFFERENTIAL CONVERTERS
Figure 2-1. Typical Converter applications.
Computer w/single-
ended host adapter
Computer w/
differential host
adapter
Computer w/
differential host
adapter
Single-ended SCSI
chain, up to 6 m
(19.7 ft.) long
Single-ended SCSI
chain, up to 6 m
(19.7 ft.) long
Differential SCSI
chain, up to 25 m
(82 ft.) long
Single-ended SCSI
chain, up to 6 m
(19.7 ft.) long
Single-ended SCSI
chain, up to 6 m
(19.7 ft.) long
Differential SCSI
chain, up to 25 m
(82 ft.) long Differential
peripherals
Converter
Computer Computer
Peripherals
Single-ended
peripherals
Differential
peripheral
Peripherals
Converter Converter
Differential SCSI
chain, up to 25 m
(82 ft.) long

13
CHAPTER 3: Installation
3. Installation
3.1 Unpacking Your Shipment
Check the contents of the shipping carton as you unpack your SCSI Differential
Converter. The package should at least contain:
• (1) SCSI Differential Converter
• (1) Package of replacement parts consisting of:
(1) 1.5-Amp input-power fuse and
(1) 1-Amp terminator fuse
• This user’s manual
Customers in North America and certain other world regions will also receive an
AC power cord. If you didn’t receive everything, or if anything arrived damaged,
call Black Box immediately.
3.2 Configuration
You will have to open the SCSI Differential Converter and make adjustments to its
internal components if you need to do any of these things:
• Set the unit for 220-VAC input power;
• Set its single-ended port for external termination (see Section 3.3.5 for a
discussion of termination options);
• Set its differential port for external termination;
• Replace any of its internal terminators; or
• Remove or replace its input-power fuse or terminator-power fuse.
Refer to Appendix C; it gives you step-by-step directions for opening the Converter
and making any of these adjustments.

14
SCSI DIFFERENTIAL CONVERTERS
3.3 Placement
Your SCSI Differential Converter requires no additional software to operate. The
only thing necessary to operate it is a nearby working AC outlet.
You can install the Converter in any position and any location near your SCSI
devices that is convenient for you. The only exceptions are:
• You must make sure that the ventilation slots on the sides of the unit get
adequate air flow.
• Don’t install the unit near any devices that generate (a) excessive heat, such as
desk lamps or radiators, or (b) excessive electrical noise, such as motors,
fluorescent lights, or compressors.
3.4 The Installation Procedure
3.4.1 A TTACHING THE P OWER C ORD
First, plug the IEC 320 female outlet on the power cord of your SCSI Differential
Converter into the Converter’s IEC 320 male inlet, shown in Figure 3-1 below. The
other end of the cord should have a plug suitable for your type of outlet, but do
not plug the cord into an outlet yet.
Figure 3-1. The rear panel of the SCSI Differential Converter
(the narrow model, IC124A, shown).
3.4.2 P OWERING D OWN THE S YSTEM
Before you insert the SCSI Differential Converter into your SCSI system, power
down all of the computers and peripherals that will be part of the same SCSI bus as
the Converter. This minimizes the chances that problems or accidental damage
will occur.
SINGLE-ENDED PORT
DIFFERENTIAL PORT

15
CHAPTER 3: Installation
3.4.3 C ONNECTING THE C ONVERTER TO THE SCSI B US
Install the SCSI Differential Converter at one end or the other of the single-ended
SCSI chain and differential chain that you want to interconnect. (That is, run
standard single-ended cable to the Converter from either the first or last device on
the single-ended chain, and run standard differential cable to the Converter from
either the first or last device on the differential chain.) The Converter has one
single-ended (50-pin Centronics®or 68-pin high-density) female connector and
one differential (50- or 68-pin high-density) female connector, with locking
tabs/clips and screwlocks respectively for secure connections. These ports are not
computer- or peripheral-specific, so you can connect cable from either a computer
or a SCSI peripheral to either of them.
Use good cable for your SCSI bus. High-quality shielded SCSI cables will provide
a link with the greatest noise immunity, and across the greatest distance, between
the Converter and your other SCSI devices. No matter how good the cable is,
however, no single-ended SCSI cable connected to the Converter may be longer
than 6 m (19.7 ft.)—3 m (9.8 ft.) if you’re running at a Fast SCSI data rate—and
no attached differential cable may be longer than 25 m (82 ft.). We highly
recommend that even differential cable runs be kept to a maximum of 5 or 10 m
(16.4 or 32.8 ft.) for optimum system performance.
CAUTION!
Do not attach a differential SCSI bus to the Converter’s single-ended
port. This could damage the Converter even though it has internal
protection.
Don’t attach a single-ended bus to the differential port, either. The
differential port is also internally protected and would not be damaged
by a brief attachment to a single-ended bus, but its voltage levels could
damage the other devices on the bus.
3.4.5 E NSURING P ROPER T ERMINATION
All SCSI buses must be properly terminated at each end. But because the SCSI
Differential Converter essentially ties together two SCSI chains that can each be as
long as an entire bus, there has to be extra termination on each side of the
Converter in addition to the standard terminators at each end of the bus.
That’s a total of four terminators—two on each side of the Converter. Figure 3-2
on the next page shows the locations of the required terminators. Be careful,
though—your system will fail if more than two terminators are installed on either
side of the Converter.

16
SCSI DIFFERENTIAL CONVERTERS
Figure 3-1. Termination in a SCSI Differential Converter system.
Your SCSI Differential Converter comes standard with internal terminators that
provide the necessary termination on each side of the Converter. However, your
application or peripherals might require that you use external terminators with the
Converter, in which case you should already have removed or replaced the internal
terminators; if you haven’t yet, see Section 3.2 and Appendix C. (The Converter
contains an internal resettable fuse that can provide power—1 amp at 5 volts—to
an external terminator. Note that the Converter contains internal protection and
will not be affected if other SCSI devices provide terminator power.)
3.4.6 P
OWERING U P THE
S YSTEM
You may now plug in the SCSI Differential Converter and turn it ON by moving
the Power switch on its rear panel to the “|” position. Check the POWER LED on
the Converter’s front panel; if it’s lit, the Converter should be powered up and
ready to go.
Now power up any SCSI peripherals on the bus, and lastly power up any host
computers on the bus. This completes the installation of your SCSI Differential
Converter; your “hybrid” single-ended/differential SCSI system should be ready for
continuous operation.
Computer
T = required terminators that you must have present
T* = required terminators that are already there (internal to the Converter)
Converter
T
T
T*
T* Peripherals

17
CHAPTER 4: Operation
4. Operation
4.1 The Front Panel and Its LEDs
Each SCSI Differential Converter has two LEDs on its front panel, shown in Figure
4-1 below, that give you at-a-glance status information about the unit’s operation:
Power—Lights when the unit is plugged in, turned ON, and receiving AC power.
Bus Active—Dark when there is no communication on the SCSI bus; flickers (in
response to the SCSI interface’s BUSY signal) when devices are
communicating on the bus.
Figure 4-1. The SCSI Differential Converter’s front panel.
4.2 System Function and Performance
The SCSI Differential Converter translates single-ended SCSI data and command
information into standard differential formats and vice versa. SCSI-bus signals are
routed through proprietary switching logic that enables the Converter to appear
“transparent” to other devices on the bus.
The Converter will support any combination of asynchronous and synchronous
SCSI devices on the bus. Overall system performance will depend on the individual
data rate and protocol of each SCSI device, plus the overhead of the host
computer.
The Converter does, however, introduce a 15-ns conversion delay between its
single-ended and differential ports. And because the Converter—especially when
used in pairs—extends the length of the SCSI bus well beyond its original design
specifications, there is also some extra propagation delay. Across a bus 30 m (~100
ft.) long, the total additional delay is approximately 150 ns. This delay might
BUS ACTIVE
POWER