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LG M4212 and Smart-E

Howdoo,

I've got a problem with controlling LG M4212 LCD monitors through Smart-E Cat5 video converters. You can send RS232 through the cat5 video distribution system and sometimes it works, but particularly the power on and off strings for these monitors gets there infrequently, or not at all. I can send the command on it's own via control a device, but when I send the same string when triggered in the program nothing happens, or it takes a couple of instances for the command to work.

Any ideas?

The string for power on and off is

'ka 0 1',$0D

Where ka is the command, the first 0 is the address, set to global in this case, and the 1 is the power status. Comm settings are 9600 N,8,1 I've tried sending discrete strings selected with a switch case or IF statements, building the string with the power status request selected by a variable, sending the string first before anything else, sending it last, nothing appears to work. But again, I can send the command on it's own via control a device and it works every time. And other commands work from the code, volume level, source selection, auto image etc. All good.

If anyone has any ideas i'll happily try them.

Comments

  • ericmedleyericmedley Posts: 4,177
    mshunt wrote: »
    Howdoo,

    I've got a problem with controlling LG M4212 LCD monitors through Smart-E Cat5 video converters. You can send RS232 through the cat5 video distribution system and sometimes it works, but particularly the power on and off strings for these monitors gets there infrequently, or not at all. I can send the command on it's own via control a device, but when I send the same string when triggered in the program nothing happens, or it takes a couple of instances for the command to work.

    Any ideas?

    The string for power on and off is

    'ka 0 1',$0D

    Where ka is the command, the first 0 is the address, set to global in this case, and the 1 is the power status. Comm settings are 9600 N,8,1 I've tried sending discrete strings selected with a switch case or IF statements, building the string with the power status request selected by a variable, sending the string first before anything else, sending it last, nothing appears to work. But again, I can send the command on it's own via control a device and it works every time. And other commands work from the code, volume level, source selection, auto image etc. All good.

    If anyone has any ideas i'll happily try them.

    The LG serial ports are notoriously flaky. We've had such a bad experience with them we've quit selling them altogether in systems that require control systems.

    My guess is that you might check the voltage of the RS232 output of the Smart E. It might be just on the edge of spec. Combine this with the flakiness of the port in general, you might have a bad combination. Just a guess.
  • The LG serial ports are notoriously flaky. We've had such a bad experience with them we've quit selling them altogether in systems that require control systems.

    My guess is that you might check the voltage of the RS232 output of the Smart E. It might be just on the edge of spec. Combine this with the flakiness of the port in general, you might have a bad combination. Just a guess.

    That's actually what occured to me. Which kind of explains why it works on it's own, but not as part of the code where other RS232 codes are being broadcast across the same RS232 network.

    I guess one solution is to address each CAT5 port individually which can be done and send the appropriate string to each device in turn. ( I have a mix of LG monitors and Panasonic projectors) This would also give me feedback from each device to prove that it is getting the command.
  • There are 2 pieces from smart-e, the 111 and the 211. It looks like the 211 might be designed for longer distance, maybe that will help. The other option if you have network access there is to use a serial server instead. Might work better for your application.
    Here's one: http://www.sena.com/products/device_servers/

    --John
  • I'm using the RX111 as the distance is only short and doesn't need to other features such as skew compensation etc. It has been suggested that I put $0D before the command as well as after. I guess this is so the LG will know that the previous command (whatever it may have been) has ended and the next command (power on/off 'ka 0 0/1',$0D) is a new command. I haven't had chance to test it yet, probably going to get a look on thursday or friday, but in the meantime any other ideas are welcome.
  • Actually, now that I'm re-reading your post I didn't realize that the commands were working consistently when you send them directly through diagnostics. I'll lean away from hardware being the issue. Are you firing the commands out through a queue in your program? Without seeing the code I'm wondering if it might be a timing issue with multiple commands flooding the LG receive buffer from your program. Also, are these multiple monitors daisy chained together for RS-232 control?

    --John
  • mshuntmshunt Posts: 23
    At the minute i'm just sending the commands from a send_string. I must admit I haven't used a send queue before so a little guidance in setting one up would be helpful. Can I guess that it's set up like a reverse buffer?

    In terms of the hardware configuration, the rs232 goes through the smart-e along with the video down the CAT5, to simplify the code, I've just been broadcasting the commands to all devices, as there's a mix of LG and Panasonic projectors on the same CAT5 distributor. The downside to this method is it appears to be confusing the LG's on some commands. I've used the same code but wired directly to the AMX, and it runs fine.

    It's been suggested that I could put $0D before the command too, I guess to let the LG know the last command has finished and the next one is a new command. It needs to be tested so we'll see how it will work out.
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