Black Box ServSwitch Uno USB Quick start guide

ServSwitch Uno USB
ServSwitch Duo USB
JANUARY 2004
KV6508SA
KV6608SA
KV6616FA
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 [phone]
Mailing address: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: [email protected]

ServSwitch Uno/Duo USB Installation and Use Page 1
About this manual
ServSwitch Uno/Duo USB - Installation and Use
www.blackbox.com
All rights reserved. While every precaution has been taken in the preparation of this
manual, Black Box assumes no responsibility for errors or omissions. Neither is any
liability assumed for damages resulting from the use of the information contained
herein. We reserve the right to change the specifications, functions and circuitry of
the product without notice. All trademarks acknowledged.
Safety information
For use in dry, oil free indoor environments only.
Do not attempt to service the ServSwitch Uno/Duo USB yourself.
Follow all warnings and instructions marked on the ServSwitch Uno/Duo USB, its
power adapter and its accessories.
Warning - live parts contained within power adapter.
No user serviceable parts within power adapter - do not dismantle.
Plug the power adapter into a socket outlet close to the ServSwitch Uno/Duo
USB.
Replace the power adapter with a manufacturer approved type only.
Do not use power adapter if power adapter case becomes damaged, cracked or
broken or if you suspect that it is not operating properly.
If you use a power extension cord with the ServSwitch Uno/Duo USB, make sure
the total ampere rating of the devices plugged into the extension cord does not
exceed the cord’s ampere rating. Also, make sure that the total ampere rating of
all the devices plugged into the wall outlet does not exceed the wall outlet’s
ampere rating.

ServSwitch Uno/Duo USB Installation and Use Page 2
Radio Frequency Energy
Shielded cables must be used with this equipment to maintain compliance with radio
frequency energy emission regulations and ensure a suitably high level of immunity
to electromagnetic disturbances.
European EMC directive 89/336/EEC
This equipment has been tested and found to
comply with the limits for a class A computing
device in accordance with the specifications in
the European standard EN55022. These limits
are designed to provide reasonable protection
against harmful interference. This equipment
generates, uses and can radiate radio
frequency energy and if not installed and used
in accordance with the instructions may cause
harmful interference to radio or television
reception. However, there is no guarantee that
harmful interference will not occur in a
particular installation. If this equipment does
cause interference to radio or television
reception, which can be determined by turning
the equipment on and off, the user is
encouraged to correct the interference with one
or more of the following measures: (a) Reorient
or relocate the receiving antenna. (b) Increase
the separation between the equipment and the
receiver. (c) Connect the equipment to an outlet
on a circuit different from that to which the
receiver is connected. (d) Consult the supplier
or an experienced radio / TV technician for
help.
FCC Compliance Statement (United States)
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 B 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 may 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
manufacturer could void the user’s authority to
operate the equipment.
Canadian Department of Communications
RFI statement
This equipment does not exceed the class A
limits for radio noise emissions from digital
apparatus set out in the radio interference
regulations of the Canadian Department of
Communications.
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 radioélectriques publié par le
ministère des Communications du Canada.

ServSwitch Uno/Duo USB Installation and Use Page 3
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.
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.

ServSwitch Uno/Duo USB Installation and Use Page 4
Contents
1. Introduction..................................................................................... 6
1.1 Key features and benefits ......................................................................8
1.2 ServSwitch Uno/Duo USB package contents.........................................10
1.3 Product information ...............................................................................11
2. Installation....................................................................................... 14
2.1 What you will need ................................................................................14
2.2 Mounting the ServSwitch Uno/Duo .......................................................16
2.3 Connecting your devices .......................................................................16
2.4 Configuring your computers ..................................................................18
2.5 Structuring your ServSwitch Uno/Duo USB installation ........................19
2.6 Maximising the video quality .................................................................23
2.7 Other useful installation information ......................................................24
2.8 Hot plugging the ServSwitch Uno/Duo into running systems and
re- enabling disconnected PS/2 CPU mouse connections .........................24
3. Configuring the ServSwitch Uno/Duo USB ................................. 26
3.1 Configuration summary..........................................................................26
3.2 Enabling password security ...................................................................27
3.3 Setting an ADMIN password..................................................................28
3.4 Creating and editing user accounts .......................................................29
3.5 Creating and editing computer names...................................................29
3.6 Setting the SETUP OPTIONS and GLOBAL PREFERENCES..............33

ServSwitch Uno/Duo USB Installation and Use Page 5
4. Using the ServSwitch Uno/Duo USB ........................................... 41
4.1 Rear panel special function switches.....................................................41
4.2 Power supply connections and indicators .............................................41
4.3 USER display and key switch.................................................................41
4.4 COMPUTER display and key switch......................................................42
4.5 Activity indicators ..................................................................................43
4.6 Selecting a computer using the front panel controls..............................43
4.7 Logging on to the ServSwitch Uno/Duo USB.........................................45
4.8 Keyboard hotkeys .................................................................................45
4.9 Selecting computers using the mouse...................................................48
4.10 Selecting computers using the on-screen menu..................................49
4.11 The reminder banner ..........................................................................53
4.12 Setting the USER PREFERENCES .....................................................54
4.13 Using the FUNCTIONS menu..............................................................55
4.14 Querying the routing status .................................................................56
4.15 Cascading ServSwitch Uno/Duos .......................................................56
4.16 Resetting user port keyboards and mice .............................................57
4.17 Using the Black Box extender .............................................................58
4.18 What to do if you forget your ADMIN password ..................................58
4.19 Saving and restoring the menu configuration to and from an Excel
compatible spreadsheet.......................................................................59
4.20 Switching channels by sending RS232 data........................................61
4.21 Keyboard equivalent key mappings.....................................................62
5. Upgrading the ServSwitch Uno/Duo's firmware ........................ 64
6. Special features of the ServSwitch Uno/Duo USB ..................... 69
6.1 Synchronising ServSwitch Uno/Duo USBs for multiple video head
applications............................................................................................69
6.2 Logging access activity .........................................................................71
Appendices
A - Cable and connector specifications................................................................73
B - Problem solving ..............................................................................................79

ServSwitch Uno/Duo USB Installation and Use Page 6
1. Introduction
Thank you for purchasing the BLACK BOX®ServSwitch Uno/Duo USB. Your
ServSwitch Uno/Duo USB is a very high performance Keyboard, Video monitor and
Mouse (KVM) sharing device which supports a wide range of computer hardware
and software platforms. The ServSwitch Duo USB supports two users and enables
each user to independently access the connected computers. The ServSwitch Uno
USB supports a single control console.
The ServSwitch Uno USB and ServSwitch Duo USB are multi-platform KVM
switches that are designed for controlling computers that have different styles of
keyboard and mouse port. Cables are available to connect to PC PS/2 style ports (6-
pin min-DIN connectors for keyboard and mouse, often colored purple and green),
USB style ports (common on many laptop and desktop PCs, Sun computers and
Apple Mac computers) and Sun style ports (8-pin min-DIN connector for keyboard
and mouse used on older style Sun computers). USB style keyboards and mice are
available for all the different styles of computer that may be controlled and so the
ServSwitch Uno/Duo USB supports USB devices to enable you to use your
preferred style of keyboard and mouse.
An On-Screen-Display (OSD) menu system is provided for easy computer selection
and control. This enables users to select computers by name or description without
having to remember the port that the computer is physically connected to. The OSD
menu system also provides a security structure that enables the system
administrator to allocate access rights to each user on a login basis.
We trust that you will be delighted with the function of your new ServSwitch Uno/Duo
USB. Product enhancement upgrades are provided free of charge during the
warranty period and may be obtained from www.blackbox.com. Some of the main
features and benefits that are offered by your ServSwitch Uno/Duo USB are listed in
section 1.1

ServSwitch Uno/Duo USB Installation and Use Page 7
Black Box explains:
What does KVM stand for?
Throughout this manual the abbreviation KVM is used to refer to the combination of
a Keyboard, Video monitor and Mouse that is used to access a computer. A KVM
console usually consists of a keyboard, monitor and mouse although sometimes
only a keyboard and monitor may be used. Devices such as the ServSwitch
Uno/Duo USB are generally known as KVM sharers or KVM switches.
What is a multi-platform KVM switch?
Multi-platform KVM switches enable you to connect to computers that have different
styles of keyboard, video and mouse ports and control all the computers from a
single keyboard, monitor and mouse.

ServSwitch Uno/Duo USB Installation and Use Page 8
1.1 Key features and benefits
Enables many computers to be independently controlled by two users.
Enables desktop and laptop PCs, Sun (USB), Sun (8-pin), Mac (USB), SGI, Alpha
and RS/6000 computers to be controlled from a common KVM console.
USB keyboard and mouse support enables KVM console devices to be chosen
that are the most appropriate for multi-platform control (keyboards and mice for all
the main computer types are available in USB format).
On-screen menu allows computers to be selected by name or description.
Configurable security enables the administrator to assign access rights to users.
Two independent users are supported on Duo models.
Advanced On-Screen Display (OSD) for easy control and configuration.
Channel switching by OSD, front panel key, keyboard hotkey, or 3 button mouse.
Supports high bandwidth monitors at resolutions up to 1920 x 1440.
Fully flash upgradeable via the serial port.
Supports a very wide range of software including Windows 3.X, WFWG, 95, 98,
2000, NT, ME, XP, DOS, Unix, Linux, NetWare, OS/2, BSD, Mac OS, Sun OS etc.
Supports several computer keyboard styles: PS/2 (6-pin mini-DIN), USB, Sun (8-
pin mini-DIN), AT (5-pin standard-DIN).
Supports several computer mouse styles: PS/2 (6-pin mini-DIN), USB, Sun (8-pin
mini-DIN), RS232 (9-pin D-type).
Supports several computer video styles: High bandwidth analog video signals with
separate or combined sync signals presented on standard 15-way HD D
connectors or 13W3 connectors.
Video channels support Display Data Channel (DDC/DDC1/DDC2) signalling.
Supports desktop and laptop PCs, Sun (USB), Sun (8-pin), Mac (USB), RS/6000,
Alpha, and Silicon Graphics computers.
Front panel "healthy voltage" indicator.
Automatic detection of the country type of the controlling keyboard enables
computers to configure themselves for the correct keyboard layout. Optionally, the
country type may be specifically defined by the user.

ServSwitch Uno/Duo USB Installation and Use Page 9
Support for up to 16 user access profiles and 512 named computers.
The colors and position of the OSD menu may be changed by each user.
OSD routing status window shows the computers that are currently being
controlled by the KVM consoles.
Supports three computer control modes - Exclusive, Shared and Video Only.
Optional small-sized reminder banner permanently confirms the selected
computer.
Compact 1U (8 port models) and 2U (16 port models) cases may be neatly fitted
under a monitor or fixed into a 19 inch rack.
User and computer name information may be uploaded to a PC and saved in an
Excel compatible file. This file may be edited in Excel and downloaded back to the
ServSwitch Uno/Duo.
Can be cascaded to a depth of four levels to provide a video switching network.
Automatically restores keyboard and mouse states when channel changed.
Supports PC keyboard modes 1,2 and 3 and PC mouse prompt and stream
modes for maximum compatibility.
Includes screen saver, auto-scan and name search options.
Supports moving or blank screen savers and auto-logout on screen save option.
Wheel mouse may be used to launch and operate the OSD menus.
User may select English, French, German or Swedish OSD menus.
Supports user definable hotkeys and mouse modes.
Positive confirmation of selected ports on local and cascaded ServSwitches
achieved by full acknowledgement signalling across all cascaded units.
Supports Microsoft IntelliMouse, IntelliMouse Explorer and other common wheel
mice.
Mouse restoration functions to enable ‘hot plugging’ of certain systems.
Front panel controls may be locked for secure operation.
Standard color-coded cable connections make installation easy and inexpensive.
Auto-scan list feature enables scanning of selected computers.

ServSwitch Uno/Duo USB Installation and Use Page 10
1.2 ServSwitch Uno/Duo USB package contents
ServSwitch Uno USB or ServSwitch Duo USB.
Power supply suitable for your country.
6 x stick on self-adhesive rubber feet.
2 x rack mount brackets.
4 x screws for fixing rack mount brackets to the sides of the ServSwitch Uno/Duo
(KV6116FA is supplied with 6 screws).
A CD-ROM containing this manual (in PDF format).

ServSwitch Uno/Duo USB Installation and Use Page 11
1.3 Product information
Fig. 1a – KV6508SA ServSwitch Uno USB viewed from the front
Fig. 1b – KV6608SA ServSwitch Duo USB viewed from the front

ServSwitch Uno/Duo USB Installation and Use Page 12
Fig. 1c – KV6616FA ServSwitch Duo USB viewed from the front
Fig. 2a – KV6508SA ServSwitch Uno USB viewed from the rear

ServSwitch Uno/Duo USB Installation and Use Page 13
Fig. 2b – KV6608SA ServSwitch Duo USB viewed from the rear
Fig. 2c – KV6616FA ServSwitch Duo USB viewed from the rear

ServSwitch Uno/Duo USB Installation and Use Page 14
2. Installation
Black Box explains:
Flexible configuration
The ServSwitch Uno/Duo USB has many ports for connection to computers,
keyboards, mice and monitors. There are no restrictions placed upon which ports
are connected to devices and you can leave any of the ports disconnected if you
wish. You do not need to connect a keyboard, monitor and mouse to each user port
if you do not wish to use all of these. You may perhaps decide to connect just a
keyboard and monitor or you may decide to connect to just one user port. All of
these configurations are supported. What's more, your devices do not all need to be
of the same type. You may wish to use a large high-resolution monitor with an
extended keyboard and a wheel mouse on one user port and a smaller monitor with
a basic mouse and keyboard on another. The ServSwitch Uno/Duo USB intelligently
handles these mixtures of devices.
2.1 What you will need
For the computer connections you will need:
Cables to connect the ServSwitch Uno/Duo USB to each of your computer
keyboard, video and mouse ports.
There are three main types of cable available from Black Box that connect to PS/2,
USB or Sun systems. Each cable type is available in various lengths. You may also
need one or more cabling adapters if you have older type 5-pin DIN keyboard
connectors, 9-pin serial mouse connectors or 13W3 video connectors. Cabling and
adapter specifications and part numbers are given appendix A. (You do not need to
connect a mouse cable if you are not using the mouse).
A suitable mouse driver for your computers. Supported types are:
-General mouse drivers that are supplied with the operating system (PC, Sun,
Mac etc.)

ServSwitch Uno/Duo USB Installation and Use Page 15
- PC PS/2 or RS232 two button mouse driver (any manufacturer).
- Microsoft mouse driver (including IntelliMouse).
- Logitech mouse driver (including two button, three button and wheel mouse).
You may also need one or more of the following adapters. These adapters may
be obtained from Black Box.
Video adapter - 13W3 male connector to 15 pin D-type connector
(Black Box part code: ACD002)
If you have a Sun computer with an older style 13W3 video connector then you
will need an adapter to convert this to the 15 way D-type format.
Keyboard adapter - 6 pin mini-DIN female to 5 pin standard DIN male
(Black Box part code: FA212)
If you have a PC with an older style 5 pin standard DIN connector then you will
need an adapter to convert this to the 6 pin mini-DIN format.
Mouse adapter - 9 pin D-type female to 6 pin mini-DIN female
(Black Box part code: FA314)
If you have a PC with an older style RS232 mouse connection then you will need
an adapter to convert this to the 6 pin mini-DIN format. There are several
specifications of these adapters that are provided with various mice. They all look
the same but unfortunately there are several common wiring schemes all of
which are different. To ensure that you have the right adapter, either purchase
this from Black Box or check your adapter against the wiring specification given
in Appendix A.
For the user port connections you will need:
A monitor with a standard VGA-style 15-pin analog video connector that will work
when connected directly to each of your computers. ServSwitch Uno/Duo USB
supports low and high resolution monitors.
A USB keyboard.
USB keyboards are available in Sun, PC and Mac styles. Each style has a slightly
different layout and different numbers of keys. Any USB keyboard may be used but
for maximum ease of use you are recommended to choose a keyboard style with at
least as many keys as the native keyboard style for the computers that you wish to

ServSwitch Uno/Duo USB Installation and Use Page 16
connect. This will avoid the need to use key combinations to create any missing
keys (e.g. the Stop, Again, Props and Undo keys for Sun systems). Sun keyboards
have more keys than standard PC keyboards which have more keys than Mac
keyboards and so if you are controlling a mixture of computers that include any Suns
you are recommended to use a Sun keyboard.
A USB mouse.
The ServSwitch Uno/Duo USB supports most ‘Internet / scroll mice’ that are
compatible with the Microsoft IntelliMouse and Sun and Mac mice.
2.2 Mounting the ServSwitch Uno/Duo USB
The ServSwitch Uno/Duo USB has been designed to be used either on a desktop or
mounted in a 19 inch rack. If the ServSwitch Uno/Duo USB is to be used on a
desktop then you will need to stick the supplied self-adhesive rubber feet to the
underside of the ServSwitch Uno/Duo USB. If the ServSwitch Uno/Duo USB is to be
mounted in a 19 inch rack then you will need to fit the rack mounting brackets to the
side of the ServSwitch Uno/Duo USB.
2.3 Connecting your devices
Ensure that the power is disconnected from the ServSwitch Uno/Duo USB and all
devices which are to be attached. Connect any keyboards, monitors and mice to the
user port connectors at the rear of the ServSwitch Uno/Duo USB (see figure 2). The
individual connectors are color coded for your convenience. If you are connecting
several KVM (Keyboard, Video monitor, Mouse) sets then you do not need to use
the same brands or mix of devices on each user port.
Next, connect each computer system unit in turn using the Black Box interface
cables that you have purchased for use with the ServSwitch Uno/Duo USB (see
Appendix A for cable specifications and part codes). These are color coded and
should connect directly to the various ports on your computers. Remember that the
video quality is maximized if the cables are kept as short as possible. Where
possible, 2 meter cables are recommended as these will give very high video
quality. Any unused computer connections can be left unconnected. The three main
cables type are shown in figure 3.

ServSwitch Uno/Duo USB Installation and Use Page 17
Figure 3 - ServSwitch Uno/Duo USB cables.
See appendix A for part codes and ordering information
To connect PCs with serial mouse connections and AT style keyboard connections
use the PC cable together with the adapters specified in appendix A. If you have an
existing 6-pin mini-DIN to 9-pin serial adapter that came with a mouse it may not be
suitable for use with the ServSwitch Uno/Duo USB as there are several different
standard wiring configurations for these adapters.

ServSwitch Uno/Duo USB Installation and Use Page 18
To connect Sun computers with older style 13W3 video connections you will need to
use the Sun cable together with a 13W3 to 15 way D-type video adapter.
The ServSwitch Uno/Duo USB is now ready for connection to the mains using the
mains power adapter supplied. It is important to apply power to the ServSwitch
Uno/Duo USB first, then power on the monitor and each of the computers in turn.
Failure to switch the ServSwitch Uno/Duo USB and computers on in the correct
order can lead to the mouse and/or keyboard not being recognized by the
computers when they are switched on. There is no ON/OFF switch and the
ServSwitch Uno/Duo USB will start to operate as soon as the power is applied.
2.4 Configuring your computers
Configure your computers in the same way that you would if your keyboard, mouse
and monitor were all connected directly. If you are connecting PC computers then

ServSwitch Uno/Duo USB Installation and Use Page 19
please bear in mind the following:
ServSwitch Uno/Duo USB emulates Microsoft compatible serial, IntelliMouse and
PS/2 mice, so ensure that your PC software is configured for a Microsoft mouse of
the correct type. Refer to the list of supported drivers in section 2.1.
2.5 Structuring your ServSwitch Uno/Duo USB installation
A single ServSwitch Uno/Duo USB may be used to manage and control 8 or 16
computers (see figure 4). For larger numbers of computers, Uno/Duo USB units may
be cascaded in a tree structure with ServSwitch Uno, Duo and Quadro products to
form a video switching network (see figure 5). The ServSwitch unit at the top of this
tree structure is normally used to control all the cascaded ServSwitches although
other configurations are possible.
The ServSwitch Uno/Duo USB and ServSwitch Uno/Duo/Quadro range are fitted
with an intelligent communication system that enables them to detect and
communicate with other ServSwitch Uno/Duo USBs so that it is able to positively
verify that all the cascaded ServSwitches have correctly responded to a switching
request from the user. The ServSwitches communicate with each other via the
keyboard cables.
ServSwitch Uno/Duo USB may be cascaded in a very flexible manner. Either 1 or 2
links may be made between cascaded ServSwitches. The number of independent
users supported by the system is determined by the number of cascade links that
have been installed. If two cascade links are made then two users have
simultaneous access to ports on the cascaded ServSwitches. The ServSwitch
intelligently manages the cascade links and allocates them on a first come first
served basis rather like a telephone network.
ServSwitch Uno/Duo USB may also be cascaded to some other Black Box KVM
switches although some restrictions may apply. Please consult Black Box if you
would like more information.
When cascading ServSwitch Uno/Duo USB keep in mind the following rules
The maximum number of layers in a ServSwitch Uno/Duo USB / ServSwitch
Uno/Duo/Quadro cascade is four.
You may cascade Uno/Duo USB and Uno/Duo/Quadro units with 1 or 2 KVM