PJFree

Free PJLink projector control for Control4. Built by an integrator, shared with integrators.

A Control4 DriverWorks driver that controls projectors over PJLink Class 1 (TCP port 4352). It uses Control4's projector proxy, so it appears in Composer as a projector with discrete video inputs, so sources bind to it and rooms use it as their video end-point like any other display.

Fully tested on Control4 (Composer Pro 2026.5.27 / OS 3.4.3), where it worked flawlessly to control a Panasonic PT-VMZ51S. It should work with any PJLink projector. Run the List Projector Inputs action to see which inputs the projector has, then change the input codes directly in the driver properties.

About this project: AI code generation was used to produce and test this driver. No warranty is provided. If you find a bug, please open an issue so the driver can be improved.

Why this exists

PJLink is an open standard. Projector manufacturers publish it so any control system can turn a projector on, pick an input and read its lamp hours. It's a handful of plain-text commands over port 4352.

So it's always been a little strange that the AV integration industry treats drivers like this as trade secrets. Some firms gatekeep their drivers and profiles as "tricks of the trade." Others license a driver once and resell it to every integrator who needs it, at a markup. For an open protocol that fits on an index card, that adds up quickly.

To be fair: if you sell a driver and stand behind it with real support, updates and someone who answers the phone, that's a product, and that's great. The problem is the driver that costs more than a nice HDMI cable, ships with no support, and leaves you on the job site at 4:45 on a Friday reading a forum thread from 2019. (Keep in mind, this driver has no support, if that makes you uneasy, please use a paid option)

PJFree takes the other route. It's free, it's public domain, and the source is right here. Read it, change it, fix it, and send the fixes back.

The bigger point is that when integrators share tools instead of hoarding them, clients get better systems and the whole industry looks better. Better systems sell more projects for everyone. A rising tide and all that. Even the tide doesn't charge a license fee.

Features

• Discrete power on/off, driven by room on/off
• Discrete input select from Control4 source selection
• Auto power-on when a source is selected. The input command is retried while the projector reports busy (ERR3) during warm-up.
• AV mute on/off
• Status polling for power state, current input, lamp hours, error flags (fan, lamp, temp, cover, filter, other) and projector name
• PJLink password authentication (MD5 challenge/response)
• Configurable PJLink code per input, set as a property
• Raw PJLink command for programming and testing
• Connect-on-demand. The driver drains its queue and then drops the socket, which avoids PJLink's 30-second idle timeout.

Inputs

The default input set matches the PT-VMZ51S, which reports 11 12 31 32 41 51 to INST ?.

Control4 input	Binding ID	Class	PJLink code
HDMI 1	1031	HDMI	31
HDMI 2	1032	HDMI	32
Computer 1	1011	VGA	11
Computer 2	1012	VGA	12
Memory Viewer	1041	HDMI	41
Network / USB	1051	HDMI	51

Binding IDs are in the 1000 range, and the last two digits match the default PJLink code, which makes them easy to read in Lua debug output.

The room binding is Video End-Point (7000, VIDEO_SELECTION). No audio end-point is included, so room audio isn't routed to the projector's built-in speaker.

PJLink input ranges are: 1x RGB, 2x Video, 3x Digital (HDMI/DVI/HDBaseT), 4x Storage, 5x Network. If you're using a different projector, check its codes (see Testing from the Lua tab) and edit the PJLink Code properties. No code changes are needed.

Installation

1. On the projector, enable PJLink in the network menu. Note the password if PJLink authentication is on.
2. Set the projector's standby mode so the network stays active while it's off. Eco/low-power standby usually disables LAN, and then power-on won't work.
3. Download PJFree.c4z from Releases (or this repo). In Composer Pro, go to Driver > Add or Update Driver and select it. This step is needed once per PC.
4. In System Design > Search, search for PJFree and drag PJFree PJLink Projector into the room. It appears as a single Projector item with a projector icon. The PJLink properties, actions and Lua tab are all on this item.
5. Set IP Address and, if used, Password.
6. Under Connections > Control/AV, bind your sources to the projector inputs and set the projector as the room's video end-point.
7. Press Query Status under Actions. Projector Name, Power State and Lamp Hours should populate.

Upgrading from v5 or earlier: v6 moved from the TV proxy to the projector proxy and renumbered the inputs, so delete the old driver and add v6 fresh, then rebind your sources. Composer doesn't always pick up new bindings on an in-place update.

Properties

Property	Description
IP Address	Projector IP
Password	PJLink password. Leave blank if authentication is off.
Send Auth With Every Command	No (per spec). Set Yes only if the projector rejects the second command in a session with ERRA.
Poll Interval (seconds)	Default 30. 0 disables polling. Lamp and error status are polled every 10th cycle.
Debug Mode	Prints TX/RX traffic to the Lua output window
Connection Status, Projector Name, Power State, Current Input, Lamp Hours, Error Status	Read-only status
[Input] PJLink Code	INPT code sent for each Control4 input

Actions

• Query Status reads the name, power, input, AV mute, error status and lamp hours.
• Power On / Power Off
• List Projector Inputs prints the projector's supported input codes (INST ?) to the Lua output.

Programming

Commands

• Power On
• Power Off
• AV Mute On
• AV Mute Off
• Send PJLink Command, for example AVMT 31 or INPT 32. Leave out the %1 prefix; the driver adds it along with the carriage return.

Variables

Variable	Values
POWER_STATE	Off / On / Cooling / Warming Up
POWER_ON	0 / 1 (warming up counts as on)
INPUT	Current input name
AV_MUTE	0 / 1
LAMP_HOURS	Hours per lamp
ERROR_STATUS	OK, or a list such as Filter Warning

Testing from the Lua tab

The Lua Command box runs Lua, not raw PJLink, so you can't type INPT 32 directly. Wrap it in Send():

Send("INPT 32")   -- switch to HDMI 2
Send("POWR ?")    -- query power
Send("INST ?")    -- list supported input codes
QueryAll()        -- full status refresh

Turn on Debug Mode to see the exchange:

PJLink: TX: <md5>%1POWR ?\r
PJLink: RX: POWR=1
PJLink: TX: %1INPT ?\r
PJLink: RX: INPT=31

Troubleshooting

Symptom	Likely cause
Connection Status shows No response from projector	Wrong IP, port 4352 blocked, PJLink disabled, or network standby off
Authentication error (check password)	PJLink password doesn't match the projector
ERR2 on an input change	The projector doesn't use that code. Run Send("INST ?") and fix the input's PJLink Code.
ERR3	Projector is busy (warming, cooling or off). Input and mute commands are retried automatically for about 2 minutes.
Won't power on from off	Network standby is disabled on the projector
'=' expected near ... in the Lua output	A raw PJLink command was typed in the Lua box. Use Send("...").

How it works

• Proxy: projector on binding 5001, with the proxy connection class set to TV. This matches Control4's own projector drivers; using a PROJECTOR class instead loads the proxy but no inputs. All AV inputs and the room end-point carry proxybindingid="5001" so they attach to the proxy device.
• Input IDs: video inputs use the 1000 range. Input selection is looked up by ID % 1000, and INPUT_CHANGED is reported the same way, following Control4's projector driver convention.
• No <combo> tag. Including <combo>True</combo> in a proxy-based driver stops Composer from creating the proxy, and the inputs and room binding then disappear from Connections.
• Network: binding 6001, TCP 4352, connected on demand with C4:NetConnect.
• Session flow:
  1. Connect, then wait for the PJLINK 0 (no auth) or PJLINK 1 <random> (auth) greeting.
  2. When auth is on, prefix the first command with md5(random + password).
  3. Send queued commands one at a time, waiting for each %1XXXX= response (5-second timeout).
  4. Disconnect after 3 seconds idle.
• Power mapping: POWR 1 (on) and 3 (warming) report ON to the proxy; 0 (off) and 2 (cooling) report OFF. The driver polls every 5 seconds during transitions.

Repository layout

driver.xml               Driver definition (proxy, connections, properties, actions, commands)
driver.lua               Driver logic
www/documentation.rtf    Documentation tab shown in Composer (RTF, like Control4's drivers)
UNLICENSE                Public domain dedication

Building

A .c4z is a zip with driver.xml at the root:

zip -r PJFree.c4z driver.xml driver.lua www

Version history

Version	Changes
6	Switched to the projector proxy (projector icon in Composer). Inputs renumbered to the 1000 range. Feedback sent as proxy notifications. Documentation converted to RTF so it renders in Composer.
5	Released as PJFree. Removed the combo flag so Composer creates the TV proxy. Added TV capability flags. Room end-point marked as a video source.
4	Inputs trimmed to the PT-VMZ51S set (HDMI 1/2, Computer 1/2, Memory Viewer, Network/USB)
3	AV and room connections bound to the proxy (proxybindingid)
2	Added the room end-point binding
1	Initial PJLink Class 1 driver

Bug reports

This driver was built with AI code generation and verified on real hardware, but every projector implements PJLink a little differently. If something doesn't work, please open an issue with:

• Projector make and model
• What you did and what happened
• Lua output with Debug Mode on

If you get it working on a projector that isn't listed here, please open an issue so it can be added to the list of tested models. Pull requests are welcome too.

Tested projectors

Projector	Status
Panasonic PT-VMZ51S	Fully working

Disclaimer

This is not an official Control4/Snap One, Panasonic or JBMIA (PJLink) product. All trademarks belong to their respective owners. It is provided as-is with no warranty. Test it in your project before deploying.

License

Released into the public domain under The Unlicense. Use, modify and redistribute it however you like.