Control LG video walls over RS-232

Most users don't need this page. It applies only to installations where several LG commercial displays are wired together as a video wall over RS-232.

If your installation uses several LG commercial displays as a video wall, you may have seen this failure: one panel turns itself off — usually because its internal clock has drifted and its built-in timer fired, or because it saw no input activity for four hours — and it stays dark. Restoring the video signal does not wake an LG panel from standby; someone has to press the remote or the power button on the back of the screen.

impressBox can close that gap by talking to the panels directly over an RS-232 serial cable. With it, the player guarantees that while your screens are supposed to be on, every panel of the wall actually is on — and heals any panel that falls asleep, within about a minute, automatically.

Availability: this feature is currently rolling out, validated on LG 55LV35A-class video walls. It is switched on per device by the impressBox team — contact us if you want it enabled for your installation.

What you get

• The whole wall turns on and off together. Your normal display controls and working-hours schedule drive all connected panels at once — not just the video signal, the panels themselves.

• Self-healing. The player checks every panel's power state continuously. If a panel has switched itself off while the screens are meant to be on, it is woken automatically. You will simply never see a half-dark wall.

• The right input, every time. Waking a panel isn't always enough — if someone pressed the remote or a panel reset itself, it can come back showing the wrong source (a blank HDMI, a TV tuner). Once the wall's correct setup has been captured (see below), the player checks every panel's input each time the screens turn on — and continuously while they run — and switches any strays back to the captured one.

• The wall's layout is on record. The capture also stores each panel's position in the video-wall grid (its tile layout), so support can see the wall's geometry remotely and tell exactly which physical screen a report is about.

• Sleep-proofing. On startup the player disables the panel settings that cause phantom shutdowns (the 4-hour auto-off, the no-signal timeout) and syncs each panel's internal clock from the player, in your device's configured time zone — the drifted clock is what caused most of these incidents in the first place.

• Remote control without a remote. Support can "press" remote-control buttons on a specific panel over the cable — useful for panels with a broken or blocked IR sensor, or panels mounted where nobody can reach them.

What you need

• LG commercial displays with RS-232 IN / RS-232 OUT ports (consumer TVs usually don't have them).

• A USB-to-RS232 adapter for the impressBox player. Adapters based on an FTDI chip are the most reliable choice; very cheap adapters can drop off the USB bus after a while.

• A crossed (null-modem) serial cable from the adapter to the first display — a straight cable will not work.

• Standard serial cables to chain the displays: first panel RS-232 OUT → second panel RS-232 IN, and so on. One cable from the player controls the whole chain.

Setting it up

1. Plug the USB adapter into the player and run the crossed cable to the first panel's RS-232 IN port.

2. Chain the remaining panels OUT → IN.

3. Give every panel a unique Set ID in its menu (the menu path varies by model — typically under General or Option settings). Use IDs between 1 and 16 — the player scans that range when it looks for screens.

4. Ask impressBox to enable RS-232 control on your player.

5. Capture the wall's correct setup. Once every panel shows the right picture, ask impressBox (or your integrator) to run a capture on the device. That records each panel's correct input — and its position in the wall — as the reference the player will enforce from then on. If you later rewire the wall or change inputs on purpose, just capture again while it looks right.

Apart from the capture, there is nothing to configure in manage. After the player restarts it detects the adapter, finds every panel on the chain by itself, applies the sleep-proofing, and starts watching over the wall. Detection works by talking to the screens, not by recognising the adapter, so any working USB-serial adapter is fine.

Day-to-day use

You don't operate this feature directly — it works underneath the controls you already use:

• Turn a screen on or off, mute it, set volume (remotely) — display on/off now also powers the physical panels.

• Set working hours so screens turn on/off automatically — the schedule drives the wall the same way.

While the display is scheduled off, the watchdog leaves the panels alone — it never wakes a wall outside working hours.

If something doesn't work

• The player doesn't find any screens. Check that the cable to the first panel is a crossed one and that it is in the RS-232 IN port; check that each panel has a Set ID between 1 and 16.

• A panel shows the wrong source after turning on. That means no capture has been taken yet (or it was taken before the wall was set up correctly). Set every panel right, then have a capture run — from then on the player fixes strays automatically. Note that panels need a few seconds after waking before they accept an input switch, so a fix lands moments after power-on, not instantly.

• One panel keeps getting "rescued". The self-healing hides it from viewers, but if the same panel keeps switching itself off, that points at the panel itself — a failing power supply or a wrong setting. The player's logs count these events per panel, so support can tell you which panel it is.

• The wall doesn't react at all. Cheap serial adapters sometimes disconnect from USB after running for a while. Re-seat the adapter, or swap it for an FTDI-based one.

For general player issues, start with Something's wrong? Start here.