How do I install CraftUA?

Install the matching mod loader (Forge, Fabric or NeoForge) for your Minecraft version. Download the .jar. Put it in the .minecraft/mods folder and launch that loader profile. Opens on Spigot — not every file is mirrored on our own servers.

What Minecraft version does CraftUA work with?

The listing gives Minecraft 1.21. This is the version stated by the author or source site, not something we verified ourselves.

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CraftUA

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CraftUA — Minecraft ↔ OPC UA

A Paper 1.21.1 plugin that links Minecraft redstone components to OPC UA server variables, letting you control and monitor industrial automation systems (PLCs, SCADA) directly from your Minecraft world!

Features

Bidirectional linking — Levers/buttons can write to OPC UA, while lamps, redstone wire, and composters can read from it.
Multiple servers — Connect to several OPC UA servers simultaneously (CODESYS, Siemens, Kepware, Node-OPCUA, etc.).
Sign-based configuration — Place a [CraftUA] sign next to any compatible device block to instantly create a link.
Browse & alias — Browse your OPC UA server address space ingame; short aliases are saved automatically so you don't have to type long node identifiers on signs.
Bit-level control — Map individual bits of integer variables to separate redstone blocks (e.g., bit:3).
Composter analog — Map composter fill levels directly to 0–8 analog OPC UA values.
Persistence — All links survive server restarts and are safely written to nodes.yml.
Certificate auth — Automatic generation of PKCS12 self-signed certificates per configured server.
Robust reconnection — Automatic exponential-backoff reconnection handling, plus manual toggle commands.
Visualization tools — Highlight linked blocks in the world and view live values in your action bar using /craftua showNodes and /craftua showNodeInfo.

⚙️ Requirements

Paper 1.21.1 (or a compatible fork)
Java 21
An accessible OPC UA server endpoint

Installation

Download the latest CraftUA.jar file.
Place it in your server's plugins/ folder.
Restart the server to generate the configuration files.
Edit plugins/CraftUA/config.yml to add your OPC UA server endpoints.

Configuration (config.yml)

Code (YAML):

servers:
MICROSOFT:
endpoint : "opc.tcp://192.168.1.100:50000"
CODESYS:
endpoint : "opc.tcp://192.168.1.101:4841"
username : "user" # optional
password : "pass" # optional
# securityPolicy: "Basic256Sha256" # optional: force a specific policy
NODE_OPC:
endpoint : "opc.tcp://192.168.1.102:4840"
# no auth needed

debug:
enabled : false

In-Game Usage

1. Browse a server

Code (Text):

/craftua browse <serverId> [namespace]

Lists all available variables on the server. Node IDs are cached locally so you can use their short names/aliases on signs.

2. Place a sign
Create a sign and place it directly adjacent to a lever, button, redstone lamp, wire, or composter:

Code (Text):

[CraftUA]
myplc
4:myVariable
bit:3 (optional — line 4)

Tip: You can also use /craftua getsign <serverId> <ns> <varName> to get a pre-filled sign item directly in your inventory!

️ Commands

Command	Description
/craftua listServers	Show configured servers and their current connection status (✔/✘).
/craftua listNodes	List all registered links, their data types, and linked block counts.
/craftua showNodes [name] [block]	Visually highlight linked blocks with gold/emerald blocks.
/craftua hideNodes	Remove highlights and restore original blocks.
/craftua showNodeInfo	Toggle live value overlay in your actionbar when looking at a block.
/craftua saveNodes	Force-save all active links to nodes.yml.
/craftua browse <serverId> [ns]	Browse OPC UA variables and cache aliases.
/craftua reconnect <serverId>	Force-reconnect to a specific server.
/craftua disconnect <serverId>	Disconnect from a specific server.
/craftua getsign <serverId> <ns> <name>	Get a pre-filled sign item for easy placement.
/craftua toggleDebug	Toggle verbose debug logging.

[HR][/HR]

Block Reference & Directions

Block	Output (MC → OPC)	Input (OPC → MC)
Lever / Button	Toggle/pulse writes true/false to OPC UA.	OPC value physically controls the lever position.
Redstone Lamp	Lights up and writes true to OPC UA.	—
Redstone Wire	Signal strength change writes 0–15 to OPC UA.	—
Composter	—	OPC UA analog value controls the level (0–8).

Output (Minecraft → OPC UA): The block's state change is caught in-game and written to the server. Great for sensors, physical start buttons, and world detectors.
Input (OPC UA → Minecraft): The block state updates automatically when the OPC variable changes via an active subscription. Great for physical indicators and actuators.
Levers and buttons work in both directions — the type of block logic determines how it is registered. When registered as an Input, the external PLC controls its state like an indicator light.

Quick facts

Edition: Minecraft Java
File type: .jar
Minecraft version listed: 1.21
How to install: Install the matching mod loader (Forge, Fabric or NeoForge) for your Minecraft version. → Download the .jar. → Put it in the .minecraft/mods folder and launch that loader profile.
Where to get it: Opens on Spigot — not every file is mirrored on our own servers.

Install steps are the general flow for this file type — How to install Minecraft Java mods & modpacks walks through it step by step.

CraftUA is a free Minecraft Java mod. Compatible with Minecraft 1.21. Downloaded 8 times (via Spigot). Download it and open it directly in the game.

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All Mods for Java All Minecraft Java mods Java mods for 1.21