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Installation, cont'd
Wiring for RS-232 Communication
RS-232 port
The three-pin, 3.5 mm captive screw connector labeled "RS-232"
is used for optional RS-232 communication between the SW
USB and a PC 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 A/V switcher that is
plugged into the RS-232 Pass Thru port.
N
Your RS-232 computer or control system should not be
one of the host devices that are being switched. Use a
separate computer for RS-232 control.
To connect your computer or control system to the RS-232
connector, use a male 9-pin, D-to-bare-wire RS-232 cable.
One end of the UC cable is terminated with a female 9-pin D
connector, and the other end is unterminated.
1.
Wire the unterminated end of the RS-232 cable to one of
the provided three-pin captive screw plugs.
2.
Plug the wired three-pole connector into the RS-232
receptacle on the switcher's rear panel.
The figure below shows how to wire this connector for RS-232.
SW USB Switcher
RS-232
Rear Ranel
RS-232 Port
Tx Rx
Connect a ground wire between
the switcher and the computer or
control system.
(Rx) Receive Pin to Transmit (Tx) Pin 3
(Tx) Transmit Pin to Receive (Rx) Pin 2
If you use cable that has a
drain wire, tie the drain wire to
ground at both ends.
RS-232 connector pin assignments
2-10
SW USB Series • Installation
Ground
9 pin HD
Connector
To Computer or
Control System
RS-232 Port
The pinout for the host PC to the SW USB is shown below:
Host PC Pin
Switcher Pin
2 (Rx)
TX
3 (Tx)
Rx
_
5 (Gnd)
RS-232 Pass Thru port
The RS-232 Pass Thru port allows you to loop through the
Transmit line of the RS-232 control port from the SW USB. This
enables you to send SIS commands to another Extron A/V
switcher. See chapter 4, "SIS Configuration and Control", for
explanations of these SIS commands.
N
Only Extron products can be controlled via this port.
The SW USB sends SIS commands to the A/V switcher in the
following loop-through modes:
•
Loop 1 mode (default) — In this mode, SIS commands
can be issued to the SW USB and/or passed through to a
connected A/V switcher via an RS-232 interface (such as
DataViewer or HyperTerminal) on your computer.
To enable Loop 1 mode, issue the
•
Loop 0 mode — In this mode, the input selection SIS
X!
command
! can be issued to the SW USB via contact
closure, the SW USB front panel buttons, or the RS-232
interface. The SW USB subsequently passes the command
through to a connected A/V switcher.
To enable Loop 0 mode, issue the
N
In Loop 0 mode, you can still issue commands to the
SW USB using the front panel buttons, RS-232, or
contact closure in both loop modes. The loop mode
selection affects only commands coming through the
RS-232 Pass Thru port.
The diagram on the next page shows how to wire the SW USB's
RS-232 Pass Thru port for use with an Extron A/V switcher.
(The SW USB's RS-232 Pass Thru port does not have a receive
pin; therefore, it does not receive responses from the connected
A/V switcher.)
SW USB Series • Installation
E
}
1LOOP
command.
E
}
0LOOP
command.
2-11
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