Extron electronics SW USB Series User manual

User Guide
SW USB Series
Switchers
USB Switchers
68-1517-01 Rev.G
06 21


Copyright
© 2008-2021 Extron. All rights reserved. www.extron.com
Trademarks
All trademarks mentioned in this guide are the properties of their respective owners.
The following registered trademarks (®), registered service marks (SM), and trademarks (TM) are the property of RGBSystems, Inc. or Extron (see the
current list of trademarks on the Terms of Use page at www.extron.com):
Registered Trademarks (®)
Extron, Cable Cubby, ControlScript, CrossPoint, DTP, eBUS, EDID Manager, EDID Minder, eLink, Flat Field, FlexOS, Glitch Free, GlobalConfigurator,
GlobalScripter, GlobalViewer, Hideaway, HyperLane, IPIntercom, IPLink, KeyMinder, LinkLicense, LockIt, MediaLink, MediaPort, NAV,
NetPA, PlenumVault, PoleVault, PowerCage, PURE3, Quantum, ShareLink, Show Me, SoundField, SpeedMount, SpeedSwitch, StudioStation,
SystemINTEGRATOR, TeamWork, TouchLink, V-Lock, VideoLounge, VN-Matrix, VoiceLift, WallVault, WindoWall, XPA, XTP, XTPSystems, and ZipClip
Registered Service Mark(SM) : S3 Service Support Solutions
Trademarks (™)
AAP, AFL (Accu-RATEFrameLock), ADSP(Advanced Digital Sync Processing), AVEdge, CableCover, CDRS(ClassD Ripple Suppression),
CodecConnect, DDSP(Digital Display Sync Processing), DMI (DynamicMotionInterpolation), DriverConfigurator, DSPConfigurator, DSVP(Digital
Sync Validation Processing), EQIP, Everlast, FastBite, Flex55, FOX, FOXBOX, IP Intercom HelpDesk, MAAP, MicroDigital, Opti-Torque,
PendantConnect, ProDSP, QS-FPC(QuickSwitch Front Panel Controller), RoomAgent, Scope-Trigger, SIS, SimpleInstructionSet, Skew-Free,
SpeedNav, Triple-Action Switching, True4K, True8K, Vector™ 4K, WebShare, XTRA, and ZipCaddy

FCC Class A Notice
This equipment has been tested and found to comply with the limits for a Class A digital
device, pursuant to part15 of the FCC rules. The ClassA limits provide reasonable
protection against harmful interference when the equipment is operated in a commercial
environment. This equipment generates, uses, and can radiate radio frequency energy and,
if not installed and used in accordance with the instruction manual, may cause harmful
interference to radio communications. Operation of this equipment in a residential area is
likely to cause interference. This interference must be corrected at the expense of the user.
NOTE: For more information on safety guidelines, regulatory compliances, EMI/EMF
compatibility, accessibility, and related topics, see the Extron Safety and Regulatory
Compliance Guide on the Extron website.
VCCI-A Notice

Conventions Used in this Guide
Notifications
The following notifications are used in this guide:
WARNING: Potential risk of severe injury or death.
AVERTISSEMENT : Risque potentiel de blessure grave ou de mort.
CAUTION: Risk of minor personal injury.
ATTENTION : Risque de blessuremineure.
ATTENTION:
•Risk of property damage.
•Risque de dommages matériels.
NOTE: A note draws attention to important information.
Software Commands
Commands are written in the fonts shown here:
^AR Merge Scene,,0p1 scene 1,1 ^B 51 ^W^C.0
[01] R 0004 00300 00400 00800 00600 [02] 35 [17] [03]
E X! *X1&*X2)*X2#*X2! CE}
NOTE: For commands and examples of computer or device responses used in this
guide, the character “0” is the number zero and “O” is the capital letter “o.”
Computer responses and directory paths that do not have variables are written in the font
shown here:
Reply from 208.132.180.48: bytes=32 times=2ms TTL=32
C:\Program Files\Extron
Variables are written in slanted form as shown here:
ping xxx.xxx.xxx.xxx —t
SOH R Data STX Command ETB ETX
Selectable items, such as menu names, menu options, buttons, tabs, and field names are
written in the font shown here:
From the File menu, select New.
Click the OK button.
Specifications Availability
Product specifications are available on the Extron website, www.extron.com.
Extron Glossary of Terms
A glossary of terms is available at https://www.extron.com/technology/glossary.aspx.

SW USB Series • Contents v
Contents
Introduction ................................................ 1
About this Guide.................................................. 1
About the SW USB Series ................................... 1
Features .............................................................. 1
USB System Architecture .................................... 2
Application Diagrams........................................... 4
Installation .................................................. 6
Rear Panel Features ............................................ 7
Wiring the Power Connector................................ 8
Wiring for RS-232 Communication .................... 11
RS-232 Port .................................................. 11
RS-232 Pass Thru Port.................................. 11
Setting Up Contact Closure Control................... 12
Controlling an Extron AV Switcher.................. 12
Connecting Multiple SW USBs in a System ....... 13
Operation.................................................. 15
Front Panel Features.......................................... 15
Operations........................................................ 16
Powering on the System................................ 16
Selecting an Input.......................................... 16
Issuing Commands to an Extron AV
Switcher via the RS-232 Pass Thru Port ....... 17
Locking and Unlocking the Front Panel
(Executive Mode) .......................................... 20
Resetting ....................................................... 20
Host Emulation (SW4 USB Plus Only) ............ 20
Troubleshooting ............................................. 21
Peripheral Emulation (SW4 USB Plus Only) .... 22
Updating Firmware ............................................ 22
SIS Programming and Control ................... 27
Host-to-Switcher Communication...................... 27
Switcher-initiated Messages .......................... 27
Error Responses............................................ 28
Using the Command and Response Table......... 28
Command and Response Table for SIS
Commands ...................................................... 29
Reference Information............................... 31

SW USB Series • Contents vi

SW USB Series • Introduction 1
Introduction
This section gives an overview of the Extron SW USB Series switchers. Topics include:
• About this Guide
• About the SW USB Series
• Features
• USB System Architecture
• Application Diagrams
About this Guide
This guide describes the Extron SW2 USB, SW4 USB, and SW4 USB Plus switchers and
provides instructions on installing, configuring, and operating them. The terms “SW USB”
and “switcher” are used throughout this guide to refer to all models.
About the SW USB Series
The SW USB Series switchers make it possible for two or four host computers to share and
switch among up to four peripheral USB devices such as mass storage devices, keyboards,
mice, and other human interface devices (HIDs). They function as USB hubs with switching
and device emulation, so that connections are maintained between host computers and
peripherals.
Features
A number of specialized features help to streamline system integration, including port status
indication, RS-232 pass-through, front panel security lockout, and multiple control points.
• Outputs — Four female USB type A connectors act as a USB hub. Each port supplies
the 500 mA, 5 V rating required in the USB specification.
• USB 2.0 compatibility — The SW USB switchers are backward compatible with
all previous USB data rate standards, including low speed (1.5 Mbps), full speed
(12 Mbps), and high speed (480 Mbps).
• Mounting — The SW USB Series switchers have compact 1U high, half-rack wide,
3 inches (7.6 cm) deep metal enclosures that can be mounted on a rack shelf or under
or through furniture.
• Host and peripheral emulation — The SW4 USB Plus model provides increased
system reliability by enabling an uninterrupted connection between host and peripheral
devices.
• Host emulation: When a keyboard or a mouse is connected to port 3 or 4 and
the appropriate rear panel DIP switch is set to On, the SW USB switches to the
connected keyboard or mouse instantly (see Host emulation (SW4 USB Plus
only) on page20 for more information).
• Peripheral emulation: The SW USB provides problem-free boot-up by constantly
emulating a keyboard and mouse to the computer or another input device,
regardless of whether or not a keyboard or mouse is actually connected.

SW USB Series • Introduction 2
• Power supply — An external power supply provides worldwide compatibility.
• RS-232 control and pass-through — The SW USB switcher can be controlled by
Simple Instruction Set (SIS) commands received via an RS-232 interface. These SIS
commands can be sent to an RS-232 controllable Extron AV switcher attached to the
SW USB RS-232 Pass Thru port (see SIS Programming and Control starting on
page27, for an explanation of the available SIS commands).
• Contact closure control — Connecting a push-button contact closure device to the
SW USB Contact port or shorting pin 1, 2, 3, or 4 to the ground (_) pin of the Contact
port provides an alternative method of input selection on the SW USB. Commands
issued via contact closure can also be passed through the RS-232 Pass Thru port to
an attached RS-232 controllable Extron switcher (see Setting Up Contact Closure
Control on page12 for more information).
• Hot key switching — (SW4 USB Plus only) When host emulation is enabled, inputs
can be selected by a combination of key presses on a keyboard connected to port 3 or
4.
• Front panel security lockout (executive mode) — To prevent unauthorized access
to the switchers, front panel lock mode can be enabled via front panel controls or SIS
commands to disable all front panel controls.
• Port status LEDs — The Active USB LEDs provide visual indication of port status and
activity for USB peripherals and all connected and active host devices.
USB System Architecture
A USB system architecture refers to the physical bus topology of USB devices connected
to a host device. USB devices include USB hubs, USB peripheral devices, or compound
devices (devices with a combination of USB hubs and USB peripheral devices built into it).
The system is organized in a tiered star topology to prevent multiple or circular attachments
to the bus. Each tier represents a degree of separation from the host device. Per USB
specifications, there are seven supported tiers, starting with the host device (or root hub)
occupying the first tier.
NOTE: Do not connect more than five daisy-chained hubs to the root hub. The
architecture does not support peripheral devices connected to USB hubs occupying
the seventh tier.

SW USB Series • Introduction 3
Tier 1
Tier 2
Tier 3
Tier 4
Tier 5
Tier 6
Tier 7
PC
Compound Device
Camera
Speaker
Hub
Root Hub
Built-in Hub
Monitor
Monitor
Monitor
Monitor
Keyboard Mouse = USB hub
= USB peripheral device
Figure 1. Tiered Star Topology Example for a Computer with Four Monitors
NOTE: Some computers include multiple hubs already connected to each other,
occupying multiple tiers in the topology. For example, many computers with USB
ports on the front and rear panels or computers with a built-in USB hub and a
compound USB peripheral device (such as a touch display) occupy two tiers. For
information about USB hubs used in Extron products, see the USB Hub Usage Chart
at www.extron.com.
To review the USB system architecture, count all the cascading hubs (including USB hubs
enclosed in computers and compound devices) between the host device and the last USB
peripheral device.
NOTE: If the host device runs Windows®or macOS™ operating systems, use the
following programs to view the hierarchical relationships between USB devices:
• Windows: Device Manager
• macOS: System Profiler or System Information
1

SW USB Series • Introduction 4
Application Diagrams
The following diagrams show examples of how an SW USB Series switcher can be
connected.
USB SWITCHING INPUT
Tx
Tx Rx
RS-232
CONTACT
1234
RS-232
PASSTHRU
USB OUTPUT HUB
USB 3
USB 1
PC 1 PC 2 PC 3 PC 4
USB 2
USB 4
0.4AMAX
12V
POWER
+
AAP102
AUTO
SWITCH
USBOUT1 USBOUT 2
USB101 Rx
Extron
SW4 USB
USB Switcher
USB
Interactive White Board
USB
USB
VTR001AAP
Video:
RED
Channel
Horizontal
Sync
Pulse
Active Video
PC PC PC PC
Figure 2. Connection Diagram for an SW4 USB Switcher with Interactive White
Board
100-240V 0.2A
50-60Hz
REMOTE
INPUTS
1
2
3
4
OUTPUT
OUTPUT
LR
SW6 VGA Ars
USB SWITCHING INPUT
Tx
TxRx
RS-232
CONTACT
1234
RS-232
PASSTHRU
USB OUTPUT HUB
USB3
USB1
PC1 PC2 PC 3 PC 4
USB2
USB4
1.5AMAX
12V
POWER
+
Extron
SW4 USB
USB
USB
RS-232 Loop-through
RS-232
VGA Outputs
VGA
VGA
Out
Annotator
Projector
Control System
with RS-232
Extron
SW4 VGA Ars
VGA/Audio
Switcher
PC
Laptop
Visualizer
Figure 3. Connection Diagram for an SW4 USB Switcher with an SW VGA Series
Switcher in an Annotator Application
2
3

SW USB Series • Introduction 5
OUTPUT
REMOTE
OUTPUT
L R
SW4 VGA Ars
100-240V 0.2A
50-60Hz
INPUTS
1
2
3
4
USB SWITCHED INPUTS
USB OUTPUTS HUB
Tx
Tx Rx
RS-232
RS-232
PASSTHRU
USB 3
USB 1 USB2
USB 4
1.5A MAX
12V
POWER
+
PC 1 PC 2 PC 3 PC4
MOUSE
ON
KEYBOARD
ON
OFF
HOST
EMULATION
CONTACT
1234
Flat Panel Display
Extron
SW4 VGA Ars
VGA/Audio Switcher
Desktop
PC #1
Desktop
PC #3
Desktop
PC #4
RS-232
Loop
-through
Extron
SW4 USB Plus
USB Switcher
USB
RS-232
RS-232
Control System
Mouse
Keyboard
VGA
Outputs
Desktop
PC #2
Figure 4. Connection Diagram for an SW4 USB Plus Switcher in a
Keyboard-Video-Mouse (KVM) Switching Application
4

SW USB Series • Installation 6
Installation
This section gives an overview of the steps to installing the SW USB Series switchers. It
also provides a description of the rear panel connectors and instructions for cabling. The
following topics are discussed:
• Installation Overview
• Rear Panel Features
• Wiring the Power Connector
• Wiring for RS-232 Communication
• Setting Up Contact Closure Control
• Connecting Multiple SW USBs in a System
Installation Overview
To install and set up the SW USB switcher:
1. (Optional) Mount the switcher to a rack shelf or furniture (see Mounting the SW USB
Series Switcher on page31).
2. Connect host devices to one or more SW USB Switched Input type B connectors,
using cable lengths of up to 15 feet (4.5 m).
3. Connect one or more peripheral USB devices to the SW USB Output Hub type A
connectors, using USB cable lengths of up to 15 feet (4.5 m).
4. (Optional) Connect an RS-232 cable between the SW USB RS-232 port and a host
computer or control system (see Wiring for RS-232 Communication on page11).
NOTE: The computer that you use for RS-232 control should not be one of the
host devices connected to any of the input ports.
5. (Optional) Connect an external Extron AV switcher to the RS-232 Pass Thru port. You
can then control this switcher via commands sent through this port.
6. (Optional) Wire one of the provided 3-pole or 5-pole captive screw plugs to a 2-button
or 4-button contact closure device, and connect the device to the SW USB Contact
port (see Setting Up Contact Closure Control on page12).
7. If using a different power supply from the one that was provided, wire a 2-pole captive
screw plug to the external power supply (see Wiring the Power Connector on
page8).
8. SW4 USB Plus only: If desired, attach a keyboard, a mouse, or both to output ports
3 or 4, and set the appropriate DIP switches for host emulation (see Host emulation
(SW4 USB Plus only) on page20).
9. Power on the USB peripheral devices, if applicable.
10. Power on the SW USB switcher.
11. Power on the host devices.

SW USB Series • Installation 7
Rear Panel Features
G
G
G
C
C
C
B
B
B
USB SWITCHED INPUT
USB OUTPUT HUB
Tx
Tx Rx
RS-232
CONTACT
12
RS-232
PASS THRU
USB 3
USB 1 USB 2
USB 4
0.7A MAX
12V
POWER
+
PC 1 PC 2
SW2 USB Rear Panel
A
A
A
D
D
D
F
F
F
G
G
GF
F
F
B
B
B
A
A
A
USB SWITCHED INPUT
USB OUTPUT HUB
Tx
Tx Rx
RS-232
CONTACT
1234
RS-232
PASS THRU
USB 3
USB 1 USB 2
USB 4
0.7A MAX
12V
POWER
+
PC 1 PC 2 PC 3 PC 4
SW4 USB Rear Panel
C
C
C
D
D
D
G
G
GF
F
FE
E
ED
D
D
C
C
C
B
B
B
A
A
A
USB SWITCHED INPUT
USB OUTPUT HUB
Tx
Tx Rx
RS-232
RS-232
PASS THRU
USB 3
USB 1 USB 2
USB 4
0.7A MAX
12V
POWER
+
PC 1 PC 2 PC 3 PC 4
MOUSE
1 2
ON
KEYBOARD
ON
OFF
HOST
EMULATION
CONTACT
1234
SW4 USB Plus Rear Panel
Figure 5. SW USB Rear Panels
AInput connectors E Emulation DIP switches
BRS-232 port FOutput connectors
CContact port GPower connector
DRS-232 Pass Thru port
AInput connectors — Connect host devices, such as computers, to these female
USB type B connectors, using cable lengths of up to 15 feet (4.5 m). Pinouts for these
connectors follow the standard pinout defined in USB standards.
BRS-232 port — Connect a host to this 3-pole, 3.5 mm captive screw connector for
RS-232 control and status feedback (see Wiring for RS-232 Communication on
page11). This port can also be used to update firmware.
NOTE: The computer that you use for RS-232 control should not be one of the
host devices connected to any of the input ports.
CContact port — If desired, connect a two- or four-button contact closure device to
this 3-pole (SW2) or 5-pole (SW4 models), 3.5 mm captive screw connector to enable
input selection via contact closure (see Setting Up Contact Closure Control on
page12).
5

SW USB Series • Installation 8
DRS-232 Pass Thru port — If desired, connect an Extron AV switcher to this 3-pole,
3.5 mm captive screw connector (see RS-232 Pass Thru port on page11).
Commands issued via the front panel, contact closure, or an RS-232 interface on a PC
or control system can be sent through this port to the connected AV switcher.
NOTE: Only Extron products can be controlled via this port.
EEmulation DIP switches — (SW4 USB Plus only) These DIP switches enable host
emulation to a keyboard and mouse connected to output ports 3 and 4. Switch 1
enables host emulation to a mouse; switch 2 enables emulation to a keyboard.
When a keyboard or a mouse is connected to port 3 or 4, and the appropriate switch
is set to On, the SW USB Plus switches to the connected keyboard or mouse instantly,
without the delay that normally occurs while the computer recognizes a new peripheral
device.
FOutput connectors — Connect peripheral USB devices, such as keyboards, mice,
storage drives, or webcams, to these female USB type A connectors, using cable
lengths of up to 15 feet (4.5 m). All outputs supply the 500 mA, 5 V rating defined in
USB standards.
NOTES:
• If your SW USB system contains multiple computers, drivers for all
connected peripheral devices should be loaded on all computers.
• The four outputs act as a USB hub. Inputs cannot be routed to specific USB
output connectors. All outputs are simultaneously connected to the selected
input.
• On the SW USB Plus, output ports 3 and 4 can be used for host emulation
with supported keyboards and mice only (see Host emulation (SW4 USB
Plus only) on page20 for more information).
GPower connector — Attach the provided external 12 VDC power supply to this 2-pole,
3.5 mm captive screw connector (see Wiring the Power Connector on page8).
Wiring the Power Connector
If using an external power supply other than the one provided with the SW USB, you may
need to wire the connector for it.
CAUTION:
ATTENTION :
• The two power cord wires must be kept separate while the power supply is
plugged in. Remove power before wiring.
• Les deux cordons d’alimentation doivent être maintenus à l’écart tant que la
source d’alimentation est branchée.
To wire the power connector:
1. Cut the DC output cord of the power supply to the length needed.
2. Strip the jacket to expose 3/16 inch (5 mm) of the conductors.

SW USB Series • Installation 9
ATTENTION:
• The length of the exposed wires in the stripping process is important. The
ideal length is 3/16 inches (5 mm). Any longer and the exposed wires may
touch, causing a short circuit between them. Any shorter and the wires can
be easily pulled out even if tightly fastened by the captive screws.
• La longueur des câbles exposés est importante lorsque l’on entreprend de
les dénuder. La longueur idéale est de 5mm (3/16inches). S’ils sont trop
longs, les câbles exposés pourraient se toucher et provoquer un court-
circuit. S’ils sont trop courts, ils peuvent être tirés facilement, même s’ils sont
correctement serrés par les borniers à vis.
3. Slide the exposed leads into a 2-pole captive screw plug and secure them by tightening
the screws, using a small screwdriver.
4. To verify the polarity of the power cord before connecting it, plug in the power supply
with no load and check the output with a voltmeter.
5. Use the supplied tie-wrap to strap the power cord to the extended tail of the connector.
Figure 6 shows how to wire the power connector.
Power Supply
Output Cord
Captive Screw
Connector
SECTION A–A
Ridges
Smoot
h
AA
Tie Wrap
3/16” (5 mm) Max.
Figure 6. Power Connector Wiring
ATTENTION:
• When you are connecting the power supply, voltage polarity is extremely
important. Applying power with incorrect voltage polarity could damage
the power supply and the regenerator. Identify the negative lead by the
ridges on the side of the cord (see figure6). To verify the polarity before
connection, plug in the power supply with no load and check the output with a
voltmeter.
• Lorsque vous connectez la source d’alimentation, la polarité de la tension
est extrêmement importante. Une alimentation avec une polarité de tension
incorrecte peut endommager la source d’alimentation ainsi que l’interface. Il est
essentiel d’identifier une connexion négative du cordon d’alimentation au niveau
des stries sur les parties latérales du cordon. Pour vérifier la polarité avant la
connexion, brancher l’alimentation hors charge et mesurer sa sortie avec un
voltmètre.
6

SW USB Series • Installation 10
• Do not tin the stripped power supply leads before attaching the captive screw
connector. Tinned wires are not secure in the captive screw connectors and
could be pulled out. They may also break after being bent several times.
• Ne pas étamer les conducteurs avant de les insérer dans le connecteur. Les
câbles étamés ne sont pas aussi bien fixés dans le connecteur et pourraient être
tirés. Ils peuvent aussi se casser après avoir été pliés plusieurs fois.
• The power supply shall not be permanently fixed to the building structure or
similar structures.
• La source d’alimentation ne devra pas être fixée de façon permanente à une
structure de bâtiment ou à une structure similaire.
• Do not place the power supply within air handling spaces or the wall cavities.
• Ne pas installer la source d’alimentation dans des espaces d’aération ou dans
des cavités murales.
• The installation must be in accordance with the applicable provisions of the
National Electrical Code ANSI/NFPA 70, Article 725 and the Canadian Electrical
Code, Part 1, Section 16.
• L’installation doit toujours être conforme aux dispositions applicables du Code
américain de l’électricité (National Electrical Code) ANSI/NFPA 70, article 75, et
du Code canadien de l’électricité, partie 1, section 16.
• The power supply must be located within the same vicinity as the Extron AV
processing equipment in an ordinary location, pollution Degree 2, and secured to
a podium, a desk, or an equipment rack within a dedicated closet.
• La source d’alimentation doit être située à proximité de l’équipement audiovisuel
Extron dans un emplacement habituel, avec un degré de pollution 2, fixée à une
estrade, un bureau, ou dans une baie technique à l’intérieur d’un placard dédié.
• Always use a power supply specified by Extron for an SW USB. Use of an
unauthorized power supply voids all regulatory compliance certification and may
cause damage to the power supply and the unit.
• Utilisez toujours une source d’alimentation fournie ou spécifiée par Extron.
L’utilisation d’une source d’alimentation non autorisée annule toute certification
de conformité réglementaire et peut endommager la source d’alimentation ainsi
que le produit final.
• If not provided with a power supply, this product is intended to be supplied by
a UL Listed power source marked with “class 2” or “LPS” and rated 12 VDC,
minimum 0.7 A.
• Si le produit n’est pas fourni avec une source d’alimentation, il doit être alimenté
par une source d’alimentation certifiée UL de classe 2 ou LPS, avec une tension
nominale 12 Vcc, 0.7 A minimum.

SW USB Series • Installation 11
Wiring for RS-232 Communication
RS-232 Port
The 3-pole, 3.5 mm captive screw connector labeled “RS-232” is used for optional RS-232
communication between the SW USB and a computer or control system. The control
system plugged into this port can issue commands to the SW USB, which can pass the
commands through to an Extron AV switcher that is plugged into the RS-232 Pass Thru
port.
NOTE: The computer that you use for RS-232 control should not be one of the host
devices connected to any of the input ports.
To connect your computer or control system to the RS-232 connector, use a female 9-pin
D-to-bare-wire RS-232 cable, such as an Extron UC50 Universal Projector Control cable.
1. Wire the unterminated end of the RS-232 cable to one of the provided 3-pole captive
screw plugs.
2. Plug the wired 3-pole connector into the RS-232 receptacle on the SW USB rear panel.
Host PC Pin Switcher Pin
_
5 (Gnd)
2 (Rx) Tx
3 (Tx) Rx
NOTE: Connect a ground wire between
the switcher and the computer or
control system.
RS-232
To Computer or
Control System
RS-232 Port
SW USB Switcher
Rear Ranel
RS-232 Port
Tx Rx
9-pin
Connector
NOTE: If you use cable that has a drain
wire, tie the drain wire to ground at
both ends.
(Rx) Receive Pin to Transmit (Tx) Pin 3
Ground
(Tx) Transmit Pin to Receive (Rx) Pin 2
Figure 7. Wiring the RS-232 Connector
RS-232 Pass Thru Port
The RS-232 Pass Thru port loops the signal received at the SW USB RS-232 control port,
the Contact (closure) port, or the front panel input buttons through the RS-232 Pass Thru
port to send SIS commands to another Extron AV switcher.
NOTE: Only Extron products can be controlled via this port.
7

SW USB Series • Installation 12
You can configure the SW USB to send SIS commands or input selections through the
RS-232 Pass Thru port to the AV switcher. Two loop modes are available:
• Loop mode 0: The port passes through SIS commands from the computer, input
selections made via contact closure, and input selections made by pressing front panel
buttons.
• Loop mode 1: The port passes only SIS commands from your computer.
See Issuing commands to an Extron A/V switcher via the RS-232 Pass Thru port on
page17 for more information on the loop modes and SIS commands.
The diagram below shows how to wire the SW USB RS-232 Pass Thru port for use with an
Extron AV switcher. The RS-232 Pass Thru port does not have a receive pin; therefore, it
does not receive responses from the connected switcher.
PC
Host
Port
SW USB Extron
AV Switcher
235Rx
RS-232
Port
Pass Thru
Port
Rx
Tx Tx
Tx
Figure 8. Connections for RS-232 Loop-through
Setting Up Contact Closure Control
Contact closure is another method of input selection. To enable input selection by contact
closure, connect a push-button contact closure device (such as an Extron CCR 2BLB,
CCR 4BLB, or CCR 204) to the SW USB Contact port.
Alternatively, you can manually short one of the pins to ground (the ground [_] pin is pin 3 for
SW2 and pin 5 for SW4 models) using a jumper. Shorting pin 1 to ground selects input 1,
pin 2 selects input 2, and so forth.
Controlling an Extron AV Switcher
For applications in which the SW USB is connected to an Extron AV switcher that can be
controlled via RS-232, inputs can be selected on both switchers by contact closure.
To set up for contact closure control of an AV switcher:
1. If desired, connect a contact closure device to the SW USB Contact port.
2. Connect the SW USB RS-232 Pass Thru port to the RS-232 port on the AV switcher
(see figure7 on the next page).
3. Issue the SIS command E0LOOP }to the SW USB to enable loop 0 mode (see
Selecting the loop mode on page18 for more information).
Figure 7 App Diagram
8