LG 42PX-D series RS232?

mpullin

I'm wondering if anyone has used RS232 control for one of these screens in a system. There's no AMX module for it, so I'm shooting strings to it based on the protocol given in the owner's manual.

The Set ID for this TV is 1.
I would like to be able to turn this TV on or off. Here is what it gives me back:

ka 1 1 -> $6B$61$20$31$20$31$0D (on) -> $F8$80
ka 1 0 -> $6B$61$20$31$20$30$0D (off) -> $80

Anyone gotten this device working before? There is another thread about an LG Plasma but the model that guy had a question about has a command structure a lot different from this one. For one thing, this model isn't supposed to require any checksum. Yes, the cable is correct, and yes, I am using SEND_STRING and not SEND_COMMAND.

I'd appreciate any experience anyone has to share on this matter. Thanks.

Thomas Hayes

Have you tried it with a checksum? I had a model a few months back that wouldn't work till I added the checksum and likewise it was not stated.

alexanbo

Think you might have the wrong strings.

I did control for a LG MW30LZ10 and the string for power on was "'ka 0 1',13" while off was "'ka 0 0',13"

Looking at the protocol if you put 0 instead of 1 for set ID it's supposed to work for any set ID, don't know if that's your problem or not, I don't remember what feedback I got from the device though.

mpullin

alexanbo wrote:

Think you might have the wrong strings.

I did control for a LG MW30LZ10 and the string for power on was "'ka 0 1',13" while off was "'ka 0 0',13"

Looking at the protocol if you put 0 instead of 1 for set ID it's supposed to work for any set ID, don't know if that's your problem or not, I don't remember what feedback I got from the device though.

13 and $0D aren't the same thing? :-|

EDIT: How would I calculate a checksum for this? Do you think it would be out of $FF like the other model?

alexanbo

Oops forgot to edit that first line, I had just looked at the raw string I sent out without reading the protocol, so I thought what turned out to be the set ID might be causing the problem.

And yeah 13 does equal $0D

mpullin

My bad,

I had put the SET BAUD command in the startup code instead of in the online event for the device. After I moved it back to the online event, everything worked. When I searched the forum, I found this is a very common newbie error. So I think I'll put it in bold;

If you are controlling a device by RS232 and you are not using a module, you must send the baud command to its port (SEND_COMMAND dvDevice, "'SET BAUD 9600,N,8,1'") when the device comes online, NOT in DEFINE_START.

Hope others can learn from this.

brooklyn79

The problem with LG plasmas is well known - we refused to use them in many instllations because of the baud rate - it it 115.200 as default and there's no way to set it up to anything different. There's possibiliyt that you may want to keep control cable as short as possible or (on the worst case) you're down to descreet infrared only

setholle

LG lcd problems

The 42 inch lg lcd, has a design flaw. IT will not work with device addressing.
Use 00 instead of 01 and it will work.
The 32 inch and 23 inch lg will work correctly. I spoke with the engineer from korea. He confirmed the problem. For the 07 sets this will be resolved.
The 42 inch requires 115,200 baud.
The smaller sets are 9600 baud.
Crazy I know. I went round and round with them on this.
Also the 42 inch will not give feedback. It will do what it is told but that is it.
Seth C. Olle

mpullin

Interesting... we have a 42 inch for this job, and we're connecting to it at 9600. It turns on and off, and the protocol works perfectly.

However, we put a Comcast CableCard into it, and it refuses to turn on via RS232. Any RS232 string sent to it while it is off is answered by mimicing the string sent to it with $0A added at the end. When the TV is turned on using the remote, all RS232 commands and acknowledgement work as usual, and the TV can be turned off. Once off, it cannot be turned on via RS232 and goes back into mimic mode.

Setting the port at 115200 does nothing, can't even get an ack.
Remove the CableCard and the TV works a-ok.

Anyone seen this behavior before? I'm still waiting to hear back from LG.

Kozak03

Same Issue here we took the comcast card out but im still not controling the LG. Here is the feedback I get.

The Set ID for this TV is 1.

"'ka 0 1',13" feedback= [ko$bf$df$bf$b7$DFw$FF]
"'ka 0 0',13" feedback= [ko$BF$DF$FF]

Yes, the cable is correct, and yes, I am using SEND_STRING.The baud is 9600,8,n,1 485 disabled.

Would like to know how you corrected the issue and if the comcast card ever went back into the LG?

LG sent me to http://136.166.4.200/files/lg_rs232_setup.exe


Thanks A.N.

annuello

I'm trying to control one of these as well. (It's rebadged as a Sherwood.) Does anyone know how to get the current power state without actually setting the state?

Thanks in advance,
Roger McLean
Swinburne University

kbeattyAMX

annuello wrote: »

I'm trying to control one of these as well. (It's rebadged as a Sherwood.) Does anyone know how to get the current power state without actually setting the state?

Thanks in advance,
Roger McLean
Swinburne University

Use 'FF' for the data to read the status. 'ka 1 FF',$0D

mpullin

Kozak03 wrote: »

Would like to know how you corrected the issue and if the comcast card ever went back into the LG?

I had forgotten about this thread, but now that it's been bumped...

The answer is, it never worked with the cable card, neither Comcast nor LG support had any intelligent solution. We simply had to add another DVR box to the project for this TV. Cable cards were a nice theory but in practice, junk.

annuello

kbeattyAMX wrote: »

Use 'FF' for the data to read the status. 'ka 1 FF',$0D

Hmmmm... It doesn't seem to be responding in th way I'd expect it to. Regardless of the power state, when I send the above string it replies with: "'a 1 OKffx',$0D,$0A" (Interesting that it changes the casing of the Fs.)

I get unique replies when setting the power state. E.g.
"'ka 1 1',$0D" turns it on and it replies with "'a 1 OK 1x',$0D,$0A"
and
"'ka 1 0',$0D" turns it off and it replies with "'a 1 OK 0x',$0D,$0A"

However, I'm tring to determine the power state without actually setting it. The power button is within reach of fiddling fingers, so I want to know if I need to send a POWER ON prior to input selection. I also want to know if I need to automatically turn off the LCD at midnight. Unless I can get a proper power query working I will have to just send the POWER ON before every input selection, and just force a POWER OFF at midnight. Could be worse I guess - at least the power is discrete rather than toggle.

Any further hints are obviously welcome.

Roger McLean
Swinburne University

kbeattyAMX

It's just what the protocol says. Sorry!