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New LED Sign Technical Details

The specific sign I was using is the 4x26 Windowfront Three Color Programmable LED Sign from Brightledsigns.com. You can buy it here for $219. BrightLEDSigns.com 4x26 Windowfront Three Color

The features it has that make it the right sign for the job:

It uses two high-brightness LEDs per pixel. Indoor signs, especially cheap 3-color ones, cannot be read in sunlight during the day.
It has a serial port and includes the cable, and the protocol was easy to reverse-engineer.
It is relatively inexpensive compared to many signs
It is powered by 5V, therefore easily married into a car with a simple step-down converter.
It is a reasonable size, small enough to fit in the back window, but large enough to be seen from quite a distance.

The Serial Protocol

I used the included software and a serial port sniffing application to reverse-engineer the protocol that this sign uses. It's a more advanced protocol than the previous NS500-UA, and runs at 9600 baud instead of super-slow 2400 baud. I've included it on this page. If you find this useful, please be sure to give me credit. The code below is in Visual Basic 6 language.

Option Explicit

Private MyComm As MSCommLib.MSComm
Private WithEvents MyTimer As VB.Timer
Private Const OneSecond = 1 / 24 / 60 / 60


Public Sub Startup(MyOwner As Form, Port As Long)

    
    Set MyComm = MyOwner.Controls.Add("MsCommLib.MsComm", "MyNS500Comm", MyOwner)
    
    ' Set up the comm settings
    MyComm.Settings = "9600,n,8,1"
    MyComm.CommPort = Port
        
    Debug.Print "Port Open: ", MyComm.PortOpen
    
End Sub


Public Sub setSignText(inTxt As String, delay As Long)

    If delay > 0 Then
        ditchMessageAt = Now + (delay * OneSecond)
    Else
        ditchMessageAt = 0
    End If

    addToLog "[LEDSIGN]", "Sending ", inTxt
    
    On Error Resume Next
    addToLog "[LEDSIGN]", "Opening COM port", Form1.COM3.CommPort
    If Not MyComm.PortOpen Then MyComm.PortOpen = True
    If Err.Number <> 0 Then addToLog "[LEDSIGN]", "COM Port error:", Err.Description: Exit Sub
    
    Dim i As Long
    With MyComm
            
        .Output = "~128" ' COde number is 128
        .Output = "~f01" ' File 01
        
        .Output = "A" ' Auto Effect
        .Output = "\c" ' Default to Orange
        .Output = "\s" ' Default to 7x6 font
        '.Output = "Red\bRed2"
        
        .Output = fixText(inTxt)
        
        ' End of message
        '.Output = Chr(&HFF) & Chr(&HFF) & Chr(&H0)
        
        ' End of message
        .Output = Chr(13) & Chr(13) & Chr(13)
        
        '.PortOpen = False
        
    End With
    
    addToLog "[LEDSIGN]", "All done!"

End Sub


Private Function fixText(s As String) As String
    
    
    'tID = 19
    
    ' Original:
    ' Default color and font
    'sC = Chr(&HEF) & Chr(&HB2)
    'eC = Chr(&HFF)
    'C = Chr(&HEF) & Chr(&HB0)
    
    's = Replace(s, "\n", Chr(13)) ' You have to reinit after the line break
    ' TODO: After line break, the current effect needs to be sent again.
    
    
    Dim sc As String
    sc = Chr(13)
    
    s = Replace(s, "\", "\\")
    s = Replace(s, "^", "\^")
    
    s = Replace(s, "<COLOR:RED>", "\a")
    s = Replace(s, "<COLOR:BRIGHTRED>", "\b")
    s = Replace(s, "<COLOR:ORANGE>", "\c")
    s = Replace(s, "<COLOR:BRIGHTORANGE>", "\d")
    s = Replace(s, "<COLOR:YELLOW>", "\e")
    s = Replace(s, "<COLOR:BRIGHTYELLOW>", "\f")
    s = Replace(s, "<COLOR:GREEN>", "\g")
    s = Replace(s, "<COLOR:BRIGHTGREEN>", "\h")
    s = Replace(s, "<COLOR:LAYERMIX>", "\i")
    s = Replace(s, "<COLOR:BRIGHTLAYERMIX>", "\j")
    s = Replace(s, "<COLOR:VERTICALMIX>", "\k")
    s = Replace(s, "<COLOR:SAWTOOTHMIX>", "\l")
    s = Replace(s, "<COLOR:GREENONRED>", "\m")
    s = Replace(s, "<COLOR:REDONGREEN>", "\n")
    s = Replace(s, "<COLOR:ORANGEONRED>", "\o")
    s = Replace(s, "<COLOR:YELLOWONGREEN>", "\p")
    
        
    ' Fonts!
    s = Replace(s, "<FONT:7BY6>", "\s")
    s = Replace(s, "<FONT:DEFAULT>", "\s")
    s = Replace(s, "<FONT:SHORT>", "\q")
    s = Replace(s, "<FONT:SHORTANDWIDE>", "\r")
    s = Replace(s, "<FONT:WIDE>", "\t")
    s = Replace(s, "<FONT:7BY9>", "\u")
    s = Replace(s, "<FONT:EXTRAWIDE>", "\v")
    s = Replace(s, "<FONT:SMALL>", "\w")
    
    
    
    s = Replace(s, "<CYCLIC>", sc & "A" & "\c")
    s = Replace(s, "<IMMEDIATE>", sc & "B" & "\c")
    s = Replace(s, "<OPENFROMRIGHT>", sc & "C" & "\c")
    s = Replace(s, "<OPENFROMLEFT>", sc & "D" & "\c")
    s = Replace(s, "<OPENFROMCENTER>", sc & "E" & "\c")
    s = Replace(s, "<OPENTOCENTER>", sc & "F" & "\c")
    s = Replace(s, "<COVERFROMCENTER>", sc & "G" & "\c")
    s = Replace(s, "<COVERFROMRIGHT>", sc & "H" & "\c")
    s = Replace(s, "<COVERFROMLEFT>", sc & "I" & "\c")
    s = Replace(s, "<COVERTOCENTER>", sc & "J" & "\c")
    s = Replace(s, "<SCROLLUP>", sc & "K" & "\c")
    s = Replace(s, "<SCROLLDOWN>", sc & "L" & "\c")
    s = Replace(s, "<INTERLACE1>", sc & "M" & "\c")
    s = Replace(s, "<INTERLACE2>", sc & "N" & "\c")
    s = Replace(s, "<COVERUP>", sc & "O" & "\c")
    s = Replace(s, "<COVERDOWN>", sc & "P" & "\c")
    s = Replace(s, "<SCANLINE>", sc & "Q" & "\c")
    s = Replace(s, "<EXPLODE>", sc & "R" & "\c")
    s = Replace(s, "<PACMAN>", sc & "S" & "\c")
    s = Replace(s, "<STACK>", sc & "T" & "\c")
    s = Replace(s, "<SHOOT>", sc & "U" & "\c")
    s = Replace(s, "<FLASH>", sc & "V" & "\c")
    s = Replace(s, "<RANDOM>", sc & "W" & "\c")
    s = Replace(s, "<SLIDEIN>", sc & "X" & "\c")
    s = Replace(s, "<AUTO>", sc & "A" & "\c")

    ' Pauses
    s = Replace(s, "<PAUSE1>", "\Z1")
    s = Replace(s, "<PAUSE2>", "\Z2")
    s = Replace(s, "<PAUSE3>", "\Z3")
    s = Replace(s, "<PAUSE4>", "\Z4")
    s = Replace(s, "<PAUSE5>", "\Z5")
    s = Replace(s, "<PAUSE6>", "\Z6")
    s = Replace(s, "<PAUSE7>", "\Z7")
    s = Replace(s, "<PAUSE8>", "\Z8" & Chr(13) & "A" & "   \Z8" & Chr(13) & "A   \Z8")

    ' Speeds
    s = Replace(s, "<SPEED0>", "\Y1") ' Fastest
    s = Replace(s, "<SPEED1>", "\Y2")
    s = Replace(s, "<SPEED2>", "\Y3")
    s = Replace(s, "<SPEED3>", "\Y4")
    s = Replace(s, "<SPEED4>", "\Y5")
    s = Replace(s, "<SPEED5>", "\Y6")
    s = Replace(s, "<SPEED6>", "\Y7")
    s = Replace(s, "<SPEED7>", "\Y8") ' Slowest
    
    s = Replace(s, "<SUN>", "^66")
    s = Replace(s, "<CLOUDY>", "^67")
    s = Replace(s, "<RAIN>", "^68")
    s = Replace(s, "<CLOCK>", "^69")
    s = Replace(s, "<PHONE>", "^70")
    s = Replace(s, "<SPECS>", "^71")
    s = Replace(s, "<FAUCET>", "^72")
    s = Replace(s, "<ROCKET>", "^73")
    s = Replace(s, "<BUG>", "^74")
    s = Replace(s, "<KEY>", "^75")
    s = Replace(s, "<SHIRT>", "^76")
    s = Replace(s, "<CHOPPER>", "^77")
    s = Replace(s, "<CAR>", "^78")
    s = Replace(s, "<DUCK>", "^79")
    s = Replace(s, "<HOUSE>", "^80")
    s = Replace(s, "<TEAPOT>", "^81")
    s = Replace(s, "<TREES>", "^82")
    s = Replace(s, "<SWAN>", "^83")
    s = Replace(s, "<MBIKE>", "^84")
    s = Replace(s, "<BIKE>", "^85")
    s = Replace(s, "<CROWN>", "^86")
    s = Replace(s, "<STRAWBERRY>", "^87")
    s = Replace(s, "<ARROWRIGHT>", "^88")
    s = Replace(s, "<ARROWLEFT>", "^89")
    s = Replace(s, "<ARROWDOWNLEFT>", "^90")
    s = Replace(s, "<ARROWUPLEFT>", "^91")
    s = Replace(s, "<CUP>", "^92")
    s = Replace(s, "<CHAIR>", "^93")
    s = Replace(s, "<SHOE>", "^94")
    s = Replace(s, "<GLASS>", "^95")
    
    ' Time
    s = Replace(s, "<TIME1>", "^D")
    s = Replace(s, "<TIME2>", "^E")
    s = Replace(s, "<TIME3>", "^F")

    s = Replace(s, "<DATE1>", "^A")
    s = Replace(s, "<DATE2>", "^B")
    s = Replace(s, "<DATE3>", "^C")

    s = Replace(s, "<BEEP1>", "^q") ' 3 beeps
    s = Replace(s, "<BEEP2>", "^r") ' 3 short beeps
    s = Replace(s, "<BEEP3>", "^s") ' Short beep

    ' Static Graphics
    s = Replace(s, "<CITYSCAPE>", "^Q")
    s = Replace(s, "<TRAFFIC>", "^R")
    s = Replace(s, "<TEAPARTY>", "^S")
    s = Replace(s, "<TELEPHONE>", "^T")
    s = Replace(s, "<SUNSET>", "^U")
    s = Replace(s, "<CARGOSHIP>", "^V")
    s = Replace(s, "<SWIMMERS>", "^W")
    s = Replace(s, "<MOUSE>", "^X")

    ' Cartoons
    s = Replace(s, "<MERRYXMAS>", "^i")
    s = Replace(s, "<HAPPYNEWYEAR>", "^j")
    s = Replace(s, "<4THJULY>", "^k")
    s = Replace(s, "<HAPPYEASTER>", "^l")
    s = Replace(s, "<HALLOWEEN>", "^m")
    s = Replace(s, "<DONTDRINKDRIVE>", "^n")
    s = Replace(s, "<NOSMOKING>", "^o")
    s = Replace(s, "<WELCOME>", "^p")

    s = Replace(s, "<TEMP>", "^H") ' Doesn't work
        
    fixText = s
    
    
End Function

Here are some examples of the messages you see on my sign:

NS500Color.setSignText "<OPENFROMRIGHT>< < < < < <", -1
NS500Color.setSignText "<OPENFROMLEFT>> > > > > >", -1
NS500Color.setSignText "<OPENFROMCENTER>< < < > > >", -1
NS500Color.setSignText "<FLASH>Backing Up<IMMEDIATE>Backing Up<PAUSE8>", -1

NS500Color.setSignText "<OPENFROMCENTER><COLOR:GREEN>Thank you!<PAUSE4><OPENFROMCENTER>  <PAUSE8>", 20
NS500Color.setSignText "<FLASH><COLOR:RED>Sorry!<IMMEDIATE><COLOR:RED>Sorry!<PAUSE8>", 10
NS500Color.setSignText "<IMMEDIATE><COLOR:GREEN>Go Around Me<PAUSE8>", 10
        
NS500Color.setSignText "<SCROLLUP>TURN OFF<SCROLLUP>HIGH BEAMS<SCROLLUP><COLOR:GREEN>thank you<SCROLLUP>  <PAUSE8>", 20
NS500Color.setSignText "<IMMEDIATE>Nice Car!<PAUSE8>", 15
NS500Color.setSignText "<SCROLLUP>Traffic Ahead<SCROLLUP>     Use Alternate Route                    ", 45
        
NS500Color.setSignText "<FLASH><COLOR:RED>ALERT!<SLIDEIN>Your <COLOR:GREEN>LEFT HEADLIGHT<COLOR:ORANGE> is Broken!                     <PAUSE8>", 45
NS500Color.setSignText "<FLASH><COLOR:RED>ALERT!<SLIDEIN>Your <COLOR:GREEN>RIGHT HEADLIGHT<COLOR:ORANGE> is Broken!                     <PAUSE8>", 45