LG 50PX2DC (Plasma TV)
8 March 2006, 07:00 by Chad Reynoldson
The LG plasmas are being integrated more frequently these days in A/V integrated systems. I don’t know much about their picture quality, but I do know alot about controlling them. This document is meant to teach you how to interpret the manual in regards to 232 communication and avoid the mistakes that I made.
Addressing (IDs)
First of all, this display is addressable with IDs from 1-99. It does come from the factory set to ID 1. The protocol supports a broadcast ID of 0 so that all connected plasmas will respond. Whenever a broadcast ID is available, use it. It may save a support call or two.
Transmission
Here are the instructions straight from the manual:
[Command][Command][ ][Set ID][ ][Data][Cr]
[Command1]: First command to control the set. (j,k,m, or x).
[Command2]: Second command to control the set.
[Set ID]: You can adjust the set ID to choose desired monitor ID number in Setup menu. When selecting set ID ‘0’, every connected the TV is controlled. Set ID is indicated as decimal (1~99) on menu and Hexa decimal (0×0~0×63) on transmission/receiving protocol.
[DATA]: To transmit command data. Transmit ‘FF’ data to read status of command.
[Cr]: Carriage Return ASCII code ‘0×0D’
[ ]: ASCII code ‘space (0×20)’
Note the [Data] column in the command list is noted as hexadecimal.
This all seems to imply a mixed format of ASCII and hexadecimal values (data and ID) in the command string. However, I found this not to be true. Any implication of hex values actually means ASCII representations of the hex values. See my NetLinx string examples later in this article.
Receiving
The reply is all ASCII as well, with ASCII encodec hex values. Here is a reply:
“‘a 00 OK 00x’”
The first thing to notice is the ID comes back as 2 characters. The data also comes back as 2 characters. These values will be an ASCII representation of hex values, so you’ll need to do a HEXTOI on these fields.
Examples
“‘ka 0 0’,13” // Power Off
“‘ka 0 1’,13” // Power On
Summary
I hope you find this information helpful. I wanted to pass along this “tribal knowledge” so others don’t spend so much time on it as I had done.
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