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Control LG Display with Serial

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Ethan
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I have a few LG 55SE3D-BE commercial digital signage displays that I would like to control with the Brightsign LS424 player. I have the USB C to 3.5mm serial cable (from Brightsign) and I have a 4 conductor 3.5mm cable going from the Brightsign player to the 3.5mm RS-232 IN port on the back of the LG Display (the LG came with a 4 conductor 3.5mm to DB9 adapter, so I went with 4 conductor 3.5mm). I setup a Bright Author project with a Time/Clock event set to Send Serial String (EOL) Port 0 with the string "ka 01 00" (not including quotes). I found that command on this site and it should power off the display. Other sites that I've found indicate this command is correct, however, it does not seem to work. I tried using the same event to send Video Enable monitor power save mode and that works, so I'm fairly certain I've got the scheduling side right. Based on this LG manual (page 64) for a different model, I've set the Baud rate to 9600 and other settings in Presentation Properties > Interactive. LG says you need a crossed cable. In properties there's an option for Invert Signal and I tried that as well. 

Any suggestions as to what I might be doing wrong or how I could go about troubleshooting this?

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  • 1
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    Allen H. Porter

    Your command is correct.  See pics below.  You don't need a TRRS (4 conductor) cable but it doesn't hurt.  But an off the shelf cable does not work as it is tip to tip, ring to ring, etc.

    And you set the Presentation Properties - Interactive port 0 to 9600, n, 8, 1.

     

    And you need to cross-over tip to ring, ring to tip, sleeve to sleeve.  If you are trying a 3.5mm to DB9 femal cable I think it is tip to pin 3, ring to pin 2, and sleeve to pin 5 but I am not 100% sure about tip and ring...could be the opposite.ka indicates power command, 0 is the address to talk to all screens regardless of their address, and 00 is off and 01 is on.

    LG OFF - ka 0 00

    LG ON - ka 0 01

    LG TO HDMI1 - xb 0 90

  • 0
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    Ethan

    Thanks for your post. I'm afraid I'm still struggling to get this to work. I have 4 of these LG displays and they each came with a 3.5mm to DB9 adapter. I took two of those and put a DB9 cable in the middle and tested it with a multi-meter. I've got tip to ring and ring to tip.

    I've got this plugged in between the Brightsign player (USB C to 3.5mm > 3.5mm to DB9 > DB9 to 3.5mm) and the LG TV

    I've got these presentation settings

    And this time based trigger

    But unfortunately this is working. Any thoughts on what I might be missing?

     

  • 0
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    Allen H. Porter

    My Send EOL and Receive EOL are CR+LF but otherwise the same.

     

    I have no experience with that USB to DB9 thing you have there.  I have never even tried a USB to Serial dongle.  I am not confident that will work.  Your pin-outs are good but that USB thing is probably the problem.  I use players with the actual 3.5mm port marked "Serial".

  • 0
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    Ethan

    Tried CR+LF on the EOL and that didn't seem to get it either. 

    The USB C to 3.5mm is from Brightsign. The LS424 doesn't have a 3.5mm port for serial, so you have to use an adapter.

    I plugged my laptop into the LG TV and tried running Putty to see if they would talk to each other. Is that sort of thing do-able? Or is RS232C different somehow? I'm not getting a response when I try that with the same baud rate and settings from above. 

  • 0
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    Allen H. Porter

    Running Putty or UTF TeraTerm with the same port settings, you should be able to do this.  I have often.  I think the LG display returns some weird characters and "OK" in response to a command.  Since most PCs no longer have a serial port I use the Trendnet TU-S9 - USB to DB9 male serial dongle.  This has the Prolific chipset and the driver is not too difficult to find.

     

    To get a response from the display try a query which is "ka 0 ff".  the "ff" is what makes it a question.

  • 0
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    Allen H. Porter

    And you do not need to "enable" serial control on the LG display...or at least I never have and we have controlled many different LG commercial displays using serial control.

  • 0
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    Ethan

    Figured it out. I plugged my laptop in and ran putty. I was expecting to get something back from the TV in the putty window, but there was nothing displayed. I typed in ka 0 00 and pressed enter and the TV shut off. 

    I then took the Trendnet USB to DB9 adapter that I was using with my laptop and plugged it into the USB A port on the USB C to A adapter (from Brightsign) I changed the settings in BrightAuthor to use port 2 and it is now turning the TV off and back on. Not sure why the USB C to 3.5mm wasn't working, but I've got a solution that works, so I'm happy. 

    Thanks so much for your help, I really appreciate it. 

    For anyone else who comes across this, the EOL in presentation properties is just CR for LG. The LG 3.5mm to DB9 is straight through and my DB9 cable is a null-modem (crossover) cable.

  • 0
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    Ethan

    Also I was able to daisy chain 3 LG displays together with the RS232 Out port, 3.5mm cable, and the ka 0 00 and ka 0 01 commands. It turns all of them off and on at the same time. (Note you don't need 4 conductor TRRS 3.5mm, you can use a regular 3 conductor TRS. Even though the LG 3.5mm to DB9 is 4 conductor TRRS.)

  • 0
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    Bright Scripters

    Great post gentlemen!

    Thanks for sharing

  • 0
    Avatar
    Jon Bloom

    I am also having the same problem with the Official BrightSign USB-C -> USB-A and 3.5mm serial adapter PN: CBL-USBC to USBA and 3.5mm Serial.

    I cannot get the LS424 to control my LG display at all. Using a serial terminal on my Mac works fine to send the screen on/off commands, but I can't get it to happen from the media player.

  • 0
    Avatar
    Allen H. Porter

    Did you set Presentation-Properties-Interactive the way I show above?  Except as Ethan says, you apparently must use port 2 instead of 0.  I haven't verified that yet as I am just starting to use the LS424.  Also did you set the commands as I show with the exception of again using port 2?  The command ka 0 00 will turn any LG commercial display off.

     

    Lastly check your pin outs are as shown above.

     

  • 0
    Avatar
    Jon Bloom

    I was hoping to use the 3.5mm port on the Official BS adapter to use the same setup. LS424 -> 3.5mm -> DB9 -> 3.5mm -> LG SM5KE. i've tried all port numbers available and none of them function with ka 0 00 or ka 0 01.

  • 0
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    Alejandro Zárate

    it is possible to use the LS424 with native (USB-C) serial port:

    https://github.com/zarpli/BSuControl

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