Extron electronics RGB 304 User manual

User’s Manual
RGB 302/304
Universal Digital Interface

Extron RGB 302/304 Universal Interface • User’s Manual
Chapter One • Introduction to the RGB 302/304
RGB302/304Features ......................................................... 1-1
SmartSave™ .......................................................... 1-2
LCDMenu Driven Controls ..................................... 1-2
Memory Blocks and Memory Cycling...................... 1-2
LevelControl(picture)............................................. 1-2
Peaking Control (sharpness)................................... 1-3
HorizontalShiftControl(centering).......................... 1-3
VerticalShiftControl(centering).............................. 1-3
AutomaticSync Output Detection ........................... 1-3
AutomaticSyncStripping ........................................ 1-3
KeyboardLockout ................................................... 1-3
Auto-switching Power Supply.................................. 1-3
AudioInterface........................................................ 1-3
DIP Switch Settings ................................................ 1-4
RS-232ControlInterfaceforRemote Control .......... 1-4
BenefitsofWindowsRGB302/304Software .......... 1-4
Front PanelControls .............................................................. 1-5
Menubutton ............................................................ 1-5
Cursorbuttons ........................................................ 1-5
Nextbutton ............................................................. 1-5
LCD Display ........................................................... 1-5
RGB302/304Specifications.................................................. 1-6
ChapterTwo • Installing the RGB 302/304
EasySetup Procedure .......................................................... 2-1
RearPanel DIP Switch Settings ............................................ 2-3
AudioConnections ................................................................ 2-3
Installation Check .................................................................. 2-4
MemoryCyclingFeature ....................................................... 2-5
Preset Memory Blocks .......................................................... 2-6
PowerSupply ........................................................................ 2-6
RS-232InterfaceSpecifications ............................................ 2-6
ApplicationDiagrams............................................................. 2-7
ChapterThree • Front Panel Menus
RGB302/304MenuSequence .............................................. 3-1
Usingthe Menu System ........................................................ 3-2
DefaultCycleMenus ............................................................. 3-3
Default Cycle Hot Keys........................................... 3-4
LanguageMenu ...................................................... 3-4
Keyboard Lock/Unlock Menu .................................. 3-5
Digital Display Sync Processing ............................. 3-5
ImageControlsMenus .......................................................... 3-6
HorizontalShiftMenu .............................................. 3-6
VerticalShiftMenu .................................................. 3-6
LevelControlMenu ................................................. 3-7
Peaking Control Menu ............................................. 3-7
Page i
Contents

Extron RGB 302/304 Universal Interface • User’s Manual
Sync Controls Menus ............................................................ 3-8
SyncOutput Menu .................................................. 3-8
Horizontal PolarityMenu ......................................... 3-9
VerticalPolarityMenu ............................................. 3-9
OptionControlsMenus........................................................ 3-10
LCDBackliteMenu ............................................... 3-10
MemoryCyclingMenu .......................................... 3-10
SystemReset Menu ............................................. 3-10
ConfirmResetMenu ............................................. 3-11
ExitMenu ............................................................................ 3-11
Default Settings on Power Up .............................................. 3-11
Default SettingsonSystemReset ....................................... 3-11
Chapter Four • Using theWindows® Control Program
InstallingWindows®ControlSoftware ................................... 4-1
NormalWindowsControlPanel ............................................. 4-2
RGB 302/304 Help ................................................................ 4-3
Appendix A • Programmer’s Guide
RemoteControlPort(RS-232) ..............................................A-1
Host-to-RGB302/304Instructions ........................................A-2
SimpleCommands ................................................................A-3
Error Codes ..........................................................................A-4
RGB 302/304-InitiatedMessages .......................................... A-5
RGB 302/304 User’s Manual
68-354-01
FirstEdition
89-03
WrittenandprintedintheUSA
Page ii
Contents

Extron RGB 302/304 Universal Interface • User’s Manual Page iii
Legend
Legend of Icons
The following icons may be used in this manual:
______ Important information – for example, an action or a
step that must be done before proceeding.
______ A Warning – possible dangerous voltage present.
______ A Warning – possible damage could occur.
___ A Note, a Hint, or a Tip that may be helpful.
____ Possible Electrostatic Discharge (ESD) damage
could result from touching electronic components.
_____ Indicates word definitions. Additional information may
be referenced in another section, or in another
document.

Extron RGB 302/304 Universal Interface • User’s Manual
Notes
Page iv
____

Extron RGB 302/304 Universal Interface • User’s Manual
1
Chapter One
Introduction to the RGB 302/304
SmartSave™
LCD Menu Driven Controls
Memory Blocks and Memory Cycling
Image Display Controls
Automatic Sync Output Detection
Keyboard Lockout
RS-232 Control Interface
Front Panel Controls
Specifications
RGB 302/304 Universal Digital Interface
User’s manual

Extron RGB 302/304 Universal Interface • User’s Manual
The Extron RGB 302/304 is a digitally controlled
UniversalAnalog/ECLComputer-VideoInterface.It
can connect most computers to a video presentation
device, such as a large screen projector or data
monitor. The RGB 302/304’s SmartSave™ feature
automatically selects sync settings and other
parameters for a quick and easy setup.
AmongtheRGB302/304 features are RGB input/
outputconnectors,an MBC power jack, audio input/
outputconnectors, an RS-232 connector, and rear
panel DIP switches.
TheRGB304is identical in performance and features
as the RGB 302 with the exception being that, unlike
the RGB 302, the RGB 304 has its 9-pin Analog/ECL
input,Audioinput,andMBCpowerjacklocatedonthe
frontpanel of the unit, as shown below. This difference
allows the RGB 304 to be installed in situations where
front panel access to such connectors may be
necessary, such as the mounting of the unit in a rack
mountenvironment.
RGB302/304Features
The RGB 302/304 features allow video output to be
controlled in several ways:
• Automaticsync output detectionand setup for quick
installation
• CustomsetupandadjustmentsmadefromtheFront
Panel(shownbelow)
• RGB 302/304 Windows® software, through an RS-232
interface
• User-writtenprogramsthroughtheRS-232port
Page 1-1
Chapter 1 • Introduction to the RGB 302/304
MENU NEXT
RGB 302
MENU NEXT
RGB 304
MBC
POWER
ANALOG/ECL
AUDIO IN
INPUT

Extron RGB 302/304 Universal Interface • User’s Manual
SmartSave ™
Thisuniquefeaturegreatlysimplifiesthevideo
configurationsetupoftheRGB302/304.The
RGB 302/304 comes preset with various video
configurationstomatchmostcomputervideo
requirements.Theproperconfigurationis
automaticallyselectedandimplementedfortheuser.
Inaddition,theRGB302/304willautomaticallysave
anyusermodificationstothevideoconfigurationand
willrecallthecorrectconfigurationwithoutneedfor
userintervention.
LCD Menu Driven Controls
The RGB 302/304 does not have front panel “knobs”
or “switches” to control its operation. Instead, the
“controls”are displayedandadjusted using theFront
Panel LCD display and the six front panel buttons.
The Front Panel display can be used in any of four
languages:English,French,SpanishandGerman.
The display serves two purposes:
1. The RGB 302/304 automatically detects and
displaysvitaltroubleshootinginformation,suchas
thehorizontalandverticalscanfrequencies.
2. The user can step through and display any of the
controlsor featuresinthe interface.
___ Chapter3hasdetailsonusingtheFrontPanel.
Memory Blocks and Memory Cycling
There are 15 preset memory blocks which store video
format information, such as video, sync and control
settings. Each block is preloaded by Extron and
definesonevideoconfiguration(e.g.VESA3,MAC16",
etc.). These preset memory blocks define most video
requirements.Inaddition,thereare25user-definable
memoryblocksavailable.
The RGB 302/304 automatically cycles through
(MemoryCycling)the user-definedmemory blocks
and loads the video format that most closely matches
thecomputer’s videooutput.Shoulda match notbe
found, the 15 preset memory blocks are searched
next (refer to
the section “Memory Cycling Feature” in
Chapter2).
Level Control (picture)
This feature is similar to the brightness control on a
datamonitor and is used to adjust the intensity of the
videolevelontheprojector/monitorscreenbyusing
the cursor keys. There are 255 levels for this control.
Page 1-2
Chapter 1 • Introduction to the RGB 302/304

Extron RGB 302/304 Universal Interface • User’s Manual
Peaking Control (sharpness)
This control is similar to the sharpness control on a
datamonitor. It is also used to compensate for long
cable runs. There are eight Peaking levels which are
selected by using the cursor keys.
Horizontal Shift Control (centering)
Thisfeature shifts the displayed image tothe left or
righton the projector/monitor screen by using the
cursor keys. There are 255 positions for this control.
Vertical Shift Control (centering)
Thisfeature shifts the displayed image up or down on
the projector/monitor screen by using the cursor keys.
Thereare 255 positions for this control.
Automatic Sync Output Detection
The RGB 302/304 automatically detects which cables
are connected and sends either Sync On Green,
CompositeSync or Separate Horizontal and Vertical
sync signals to the correct output cables. This
functioncanbeoverriddenthroughmenucontrols.
Automatic Sync Stripping
The RGB 302/304 automatically strips all incoming
sync from the red, green, and blue channels for clean,
crisp signal processing. Sync may be recombined with
the green channel if necessary.
Keyboard Lockout
The RGB 302/304 features a Keyboard Lockout
function which allows the user to “lock out” the front
panel controls by using “hot keys”. This feature
disablesfrontpaneloperationaftersetup.
Auto-switching Power Supply
The RGB 302/304 is equipped with an internal auto-
switchingpower supply that operates from any input
voltage in the 100 to 240 VAC, 50/60 Hz range. No
equipmentchangesarenecessary.
Audio InterfaceThe RGB 302/304 includes a PC/computer audio (600
ohm)toline-levelaudio(balanced)converter.For
computers which have a sound card, the audio
interfacewill process theaudiosignalalong with the
video(audiofollow).Theaudiooutputcanbe
connected to an external stereo system.
Page 1-3
Chapter 1 • Introduction to the RGB 302/304

Extron RGB 302/304 Universal Interface • User’s Manual Page 1-4
Chapter 1 • Introduction to the RGB 302/304
DIP Switch Settings
The RGB 302/304 includes a rear panel DIP switch
bank which will activate Digital Display Sync
Processing, remove/pass serration pulses, and set 75
Ohm/highimpedancevideoinputtermination.
RS-232 Control Interface for Remote Control
The RGB 302/304 has a built-in RS-232 interface to
allowtheunittobecontrolledremotelyineitheroftwo
ways:
1. Use the Windows® RGB 302/304 Control Panel
software provided by Extron (see next section).
2. The user may write software to control the RGB 302/
304 from a PC or control system. See the
Programmer’s Guide inAppendixA.
The RS-232 protocol is fixed at 9600 baud, no parity, 8
data bits and 1 stop bit.
Benefits of Windows® RGB 302/304 Software
Usingthe Windows® software provided with the
RGB 302/304 adds several advantages over Front
Paneloperation.
• All of the controls are quick and easy to use with
theon-screencontrolpanel.
• Application setups can be stored as disk files,
therefore,anunlimited numberofsetupscanbe
stored and reloaded from the PC’s hard drive or
floppydisk.
Refer to Chapter 4 for details on using this software.

Extron RGB 302/304 Universal Interface • User’s ManualPage1-5
FrontPanel Controls
The Front Panel buttons (as shown below) have many
functions, depending on which menu is accessed at
anyparticular time. For example, the user can display
andadjust controls to modify the video display. The
specific functions for these buttons are described
below.
The LCD panel cycles through 3 default menus when
the RGB 302/304 is first powered on. Refer to Chapter
3 for instructions on using the RGB 302/304 menus.
___ Thereisabuilt-intime-outfunction which will return to
the default menu cycle if no buttons are pressed for
approximately 8seconds.By default, any changes
whichweremadewillbeautomaticallysaved uponthe
time-out.
Menu button TheMenu button is used to selectand step through
thefourdifferentmenuclasses(tobeexplained in
Chapter3).
Next button The Next button is used to advance to the next
submenuof a menu class or to return to the beginning
of the menu class (seethemenuflowchartonpage3-1).
Cursor buttonsThe cursor buttons are typically used to step through
themenuoptionsbefore makinga choice.These
optionscouldbealphacharactersornumericsettings.
The user may also want to change the value of the
current setting (i.e., increase or decrease level, shift,
peaking, etc.). These buttons also serve as
convenient “hot keys” to various functions.
LCD Display Besidesdisplaying the menus, the LCD display
providessomehelpfulinformation,suchaswhich
buttons to use when making choices.
MENU NEXT
RGB 302
MENU NEXT
RGB 304
MBC
POWER
ANALOG/ECL
AUDIO IN
INPUT
MENU
NEXT
Chapter 1 • Introduction to the RGB 302/304

Extron RGB 302/304 Universal Interface • User’s Manual
RGB 302/304 Specifications
Part Number ..60-243-01(RGB302)
..60-244-01(RGB304)
User’sManual ..68-354-01
Dimensions ..8.75" W x 9.5" D x 1.75" H
ShippingWeight ..5 lbs
Input Power ..100 - 240 VAC, 50/60 Hz,
auto-switchable, internal
PowerConsumption ..17 watts
OperatingTemperature ..0° C to 50° C
Control Baud Rate ..9600baud
InputSignal: Video ..2V p-p max
VideoImpedance ..75 Ωterminated,7.5kΩuntermin.
Sync ..Separate H & V Sync TTL (±)
..Composite H & V TTL (±)
..Sync on Green (-).3V
..Sync on Red, Green & Blue (-).3V
SyncImpedance ..10 kΩ
Audio ..Connector: 3.5 mm jack
AudioImpedance ..High Z
Output Signal: Video ...35V to 1V p-p with .7V applied
VideoImpedance ..75 Ω
Sync ..Sync on Green (-)
..Composite Sync (-)
..Separate H & V (±)
SyncImpedance ..75 kΩ
Audio ..Connector: 3.5 mm jack
AudioImpedance ..600 Ω
FrequencyCompatability:
Horizontal ..15 - 125 kHz (automatically)
Vertical ..30 - 170 Hz (automatically)
RGBVideoBandwidth ..220 MHz (2 ns rise time)
LCD Scan Rate Range:
Horizontal ..15 - 150 kHz
Vertical ..30 - 170 Hz
LCD Menu (Front Panel): ..Back-litalphanumericdisplay
(English, German, Spanish or
French)
Warranty ..Two years, parts and labor
Chapter 1 • Introduction to the RGB 302/304
Page1-6

Extron RGB 302/304 Universal Interface • User’s Manual
Chapter 1 • Introduction to the RGB 302/304
Page1-7
____

Extron RGB 302/304 Universal Interface • User’s Manual
2
Chapter Two
Installing the RGB 302/304
Easy Setup Procedure
DIP Switch Settings
AudioConnections
Installation Check
Memory Cycling Feature
RS-232Specifications
RGB 302/304 Universal Digital Interface
User’s manual

Extron RGB 302/304 Universal Interface • User’s ManualPage 2-1
Chapter 2 • Installing the RGB 302/304
____ The diagrams aboveshow the front andrear panels of
theRGB 302 (top pair) and RGB 304 (bottom pair).
EasySetupProcedure
Theseeasy-to-follow steps describe the general setup
ofthe RGB302/304.Refer to theexample Application
Diagrams
at the end of this chapter.
1.Turn thecomputerand monitorpowerOff.
Do not connect the RGB 302/304 power cable yet
(there is no power switch).
2.Disconnectandremovethecomputer’slocalmonitor
videocablefromthecomputervideoport.
3. Connect BNC output cables from the RGB 302/304
tothedatamonitor/projector —allBNC outputsare
RGB analog. The BNC connectors are marked R, B,
G, H/V and V. They may be connected in any of
three ways:
• Red, Green/sync and Blue, for RGB with sync on
Green.(3-cablehookup)
• Red, Green, Blue and H/HV, for RGB with Composite
sync signals. (4-cablehookup)
• Red, Green, Blue, H/HV and V, for RGB with separate
HorizontalandVerticalsyncsignals.(5-cablehookup)
MENU NEXT
RGB 304
OUTPUT
R
50/60 Hz
100-240V 0.5A
G B H/HV V
LR
OUT
MBC
POWER
RS-232
ANALOG/ECL
AUDIO IN
AUDIO
DDSP SER REM 75 OHM
INPUT
MENU NEXT
RGB 302
OUTPUT
R
50/60 Hz
100-240V 0.5A
G B H/HV V
LR
OUT IN
MBC
POWER
RS-232
ANALOG/ECL
INPUT
AUDIO
DDSP SER REM 75 OHM

Extron RGB 302/304 Universal Interface • User’s Manual Page2-2
Chapter 2 • Installing the RGB 302/304
____ The Extron RGB 302/304 automatically detects which
cables are connected and sends sync signals to the
correctoutput.
4.Connect the Analog/ECLMBCvideocable from the
computer (Power PC, PC, Mac, or workstation) to
theAnalog/ECL Inputconnectoron the RGB302/
304andtothelocalmonitor.Seenotebelow.
____ If a Laptop Breakout Cable (LBC) is being used, set
DIP Switch 3 to Off. Refer to “Rear Panel DIP Switch
Settings”in the next section.
4a. MBC Power Connector — If an MBC buffer is
beingused, plugthephonejack into theMBC
powerfemaleconnectoroftheRGB302/304.
5. RS-232 Control (optional) — If using a PC or other
system to control the RGB 302/304, connect the
cablehere(pinoutsandinterfacespecificationsare
givenunderthesection
“InstallationCheck” later in
thischapter).
6.Turn power On at the local computer monitor. Next,
turnpowerOn at thecomputersupplyingthe video
input — (Power PC, PC, Mac or workstation).
6a.TurnpowerOn atthedatamonitor/projector.
6b.ConnectpowertotheRGB302/304.
7. Observe that the RGB 302/304 LCD display lights up
andcyclesthrough thethreedefaultmenus(below).
7a. The ID or Title Menu - Displays the name of
theunit. To changethisdisplay,see
“Editing
the ID Screen”
in Chapter 3.
7b.The Scan Rate Menu-Fromthe monitor
breakout cable, the RGB 302/304 detects
the scan rate frequencies and displays
them. The scan rate display on the left is an
example.
7c.The Sync Output-Memory Cycling Menu -
As an example, if the RGB 302/304 has
detected an output with sync on Green and
Memory Cycling is turned On, the first line
will display “Sync Out: Green” and the
second line will display “Mem Cycling: On” .
Referto the
“MemoryCyclingFeature”
sectionin this chapter for a detailed
explanationofMemoryCycling.
ANALOG/ECL
INPUT
RS-232

Extron RGB 302/304 Universal Interface • User’s ManualPage2-3
____ Memory Cycling can be On or Off. Sync Output can be
Green,Comp(Composite),H&V(SeparateHorizontal
&Vertical), or Auto (Automatic).
AutomaticSync
means the RGB 302/304 detects which output
connectors are currently active and will set and display
the output sync as either Green, RGBS or RGBHV,
dependingontheconnections.
Rear Panel DIP Switch Settings
The RGB 302/304 has three DIP switch settings:
Switch 1: On = Digital Display Sync Processing
Off = Processed sync (normal)
Switch 2: On = Remove serration pulses
Off = Pass serration pulses (normal)
Switch 3: On=75-Ohminputtermination
Off=Highimpedanceinputtermination
AudioConnections
TheRGB 302/304providesaudio interfacing tothe
audiooutput which is connected to the user’s audio
equipment.Theusersuppliestheaudiocables.
Onthe RGB 302, the audio inputand output are both
locatedon the rear panel, as shownin the diagram to
theleft.
The RGB 304 has the audio output
locatedon therearpanel, butthe
audioinputissituated onthe front
panel,as shown to the right.
The audio interface is a PC/computer audio (600 Ω)to
line-levelaudio(balanced)converter.Ifthecomputer
has a sound card, the RGB 302/304 will distribute the
audiowiththevideo(audiofollow).
Althoughtheinputandoutputaudioconnectorsare
physically the same, they are used differently. See the
illustrationandthefollowingdescriptionsforthe
correctwiring of audio inputs and outputs.
Audio Input — Connect the stereo audio sources to
Audio In. Input cables should be wired as follows:
• Stereo left to Tip (+) contact
• Stereo right to Ring (-) contact
• Both commons to Sleeve (Gnd) contact
Chapter 2 • Installing the RGB 302/304
DDSP SER REM 75 OHM
On
Off 123
LR
OUT IN
AUDIO
RGB 302
AUDIO IN
LR
OUT
AUDIO
RGB 304

Extron RGB 302/304 Universal Interface • User’s Manual Page2-4
Chapter 2 • Installing the RGB 302/304
AudioOutput (Left and Right) — There is one audio
outputusing separate connectorsforleftand right
channels. Connect the left and right output jacks to the
inputs of an external audio system. The 3-contact
outputscan be wired for balanced or unbalanced
audio.
• For unbalanced audio, use Tip (+) and Sleeve (Gnd)
• For balanced audio, use Tip (+) and Ring (-)
____ Observe polarity when making connectionsto keep left
andrightchannelsinphase.
InstallationCheck
Toverifythattheinstallationiscomplete,do the
following:
1. Check that the LCD default menus show the correct
information(as previously described in Step 7).Use
themenusasatroubleshootingaid.
If no video input was detected, no memory
block was loaded, and the display will show
zeroes.
The scan rate menu may be used for
troubleshootingasfollows:
• The timing for the RGB 302/304 is derived from
the vertical sync signal. If the vertical sync signal
isnot present, both theverticalandhorizontal
frequencies will be zeroes, even if there is a
horizontalsignalpresent.
• If a vertical sync signal is detected and the
horizontal sync is not detected, the vertical
frequencyis displayed,butthe horizontal
frequency is zeroes.
2. Recheck the previous Easy Setup Procedure steps
for correct cable connections, etc.

Extron RGB 302/304 Universal Interface • User’s Manual
Chapter 2 • Installing the RGB 302/304
MemoryCyclingFeature
The RGB 302/304 is preset at the factory with fifteen
video formats which are stored in memory blocks.
These memory blocks contain video formats which
will match most computers. There are also 25
additionalemptymemoryblockswhichareuser-
defined.
When a video input is connected and the RGB 302/
304is powered On, the25user-definedmemory
blocks are scanned (cycled) sequentially for a
configurationwhichmatchesthecomputer’svideo
input. If a match is found, that format’s stored settings
areimplemented. If amatchisnot found, the 15preset
video formats are scanned next. If a match is found,
thatformat and anyadjustmentstothe image are
automaticallysaved to a user-defined memory block (if
Memory Cycling is set On). If a match is not found
amongthepresetformats, a new video format will be
createdand stored (see note below) as a user-defined
memoryblock.
The25user-definedmemory blocksare filled
sequentially (1 to 25). If the last empty memory block
(#25)has already been filled and anew video format is
added,memoryblock#1willbeoverwritten.Additional
newformatswillsequentiallyoverwritememoryblocks
#2, #3, #4, etc., and start over again at memory block
#1, #2, #3, etc.
The15 preset memory blocks are permanently stored,
while the 25 user-defined memory blocks can only be
clearedby resetting the RGB 302/304 (refer to
SystemResetMenu inthe
“OptionControlsMenus”
section of Chapter 3). Powering Off the RGB 302/304
will not delete any of the memory blocks.
____ If Memory Cycling is disabled (set Off), any changes to
avideo configuration will not be stored in a memory
block and no new memory blocks will be saved. Refer
toMemory Cycling Menuinthe“OptionControls
Menus” section of Chapter 3.
Page2-5

Extron RGB 302/304 Universal Interface • User’s Manual Page2-6
Chapter 2 • Installing the RGB 302/304
PresetMemory Blocks
TheMemoryCyclingfeaturesupports25user-defined
memoryblocksforstoring video configurations and 15
permanentlydefinedmemoryblocks.The15preset
memoryblockvideoconfigurationsarelistedbelow.
No. Format HorizontalFrequency[kHz] VerticalFrequency [Hz]
1 VGA1 31.5 70
2 VGA2 31.5 70
3 VGA3 31.5 60
4 VESA1 35.2 56
5 VESA2 37.9 72
6 VESA3 48.4 60
7 VESA4 56.4 70
8 VESA5 38.0 60
9 VESA6 48.0 72
10 Mac 13" 35.0 67
11 Mac 16" 49.7 75
12 Mac 21" 68.7 75
13 Sun1 71.7 76
14 Sun2 81.0 76
15 SGI 63.9 60
PowerSupplyThe RGB 302/304 is equipped with an internal auto-
switchingpower supply that operates from any input
voltage in the 100 to 240 VAC, 50/60 Hz range. No
equipmentchangesarenecessary.
RS-232InterfaceSpecifications
9600 baud, no parity, 8 data bits and 1 stop bit.
RS-232 Connector Pins are assigned as follows:
Pin Signal Pin Signal Pin Signal
1 — 4 — 7 —
2 Transmit 5 Ground 8 —
3 Receive 6 — 9 —
RS-232