[VRChat] Network Events: Ringing a Chime for Everyone Present

Synced variables let you share a door's state. But some things don't fit into a variable.

"Ring the chime now." "Launch the fireworks now." Things that only need to happen in that moment, with nothing left behind.

That's what Network Events are for. This article builds a chime that rings for everyone when pressed.

What You'll Learn

• When to use "state that persists" versus "a cue in the moment"
• The three targets (All / Others / Owner)
• That late joiners don't receive it
• How to handle rapid presses

Start from having tried networking basics.

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Variables are a blackboard, events are shouts

The analogy from the networking introduction works here too.

A synced variable is a blackboard. Write on it and someone arriving later can read it. That's why it suits state like "is it open right now."

A Network Event is a shout. It reaches everyone present, and the voice doesn't linger. It doesn't reach anyone arriving later.

The distinction comes down to one question.

Should someone arriving later know about this?

What you want to convey	Yes / no	What to use
Whether the door is open	Yes	Synced variable
Whether the light is on	Yes	Synced variable
A game's score	Yes	Synced variable
The chime ringing now	No	Network Event
The firework going up now	No	Network Event
The buzzer for someone's correct answer	No	Network Event

Think "there's no need to replay a past sound effect" and events are enough. Conversely, conveying a door's state with events alone leaves it closed on a late joiner's screen.

Hands-On: Ring a chime for everyone

Press a button and a chime rings on the screen of everyone present.

1. Place the button and the sound

Place two things in a scene with a floor.

Name	How to make it, and settings
ChimeButton	Cube. (0, 1, 1), Scale (0.4, 0.4, 0.4)
ChimeSource	Create Empty with an Audio Source added. (0, 2, 0)

Put a short sound effect in ChimeSource's Audio Source and turn Play On Awake off and Loop off. It rings from a button, so it shouldn't ring on its own.

Setting Spatial Blend to 0 (2D) makes it the same volume wherever you are in the room.

2. Write the code

In Assets/Scripts, choose "Create → U# Script" and make ChimeBell.

using UdonSharp;
using UnityEngine;
using VRC.SDKBase;
using VRC.Udon.Common.Interfaces;

[UdonBehaviourSyncMode(BehaviourSyncMode.Manual)]
public class ChimeBell : UdonSharpBehaviour
{
    [SerializeField] private AudioSource chime;
    [SerializeField] private float cooldownSeconds = 1f;

    private float nextAllowedTime;

    public override void Interact()
    {
        // Block rapid presses
        if (Time.time < nextAllowedTime) return;
        nextAllowedTime = Time.time + cooldownSeconds;

        // Have everyone present (including me) run PlayChime
        SendCustomNetworkEvent(NetworkEventTarget.All, nameof(PlayChime));
    }

    // Methods called from the network need NetworkCallable
    [NetworkCallable]
    public void PlayChime()
    {
        if (chime != null) chime.Play();
        Debug.Log("[ChimeBell] rang");
    }
}

Three points.

[NetworkCallable] is required. Without it, it can't be called across the network. And there's no error — nothing simply happens, which makes the cause hard to spot.

NetworkEventTarget.All includes you. Calling PlayChime() yourself as well, just in case, plays the sound twice. Sending is enough.

nameof() is used. Writing a method name as a string means it silently stops working when you rename it later.

[UdonBehaviourSyncMode(BehaviourSyncMode.Manual)] is attached because network events can't be sent with sync mode None. Even without synced variables, this specification is required.

3. Assign it and confirm

Add a Udon Behaviour to ChimeButton and set ChimeBell. Drag ChimeSource into Chime and set Interaction Text to Ring the chime.

Check with Build & Test and Number of Clients set to 2.

Order	Action	Expected result
1	A presses	The sound plays on both A's and B's screens
2	A presses rapidly	It rings once per second
3	B re-enters	Nothing rings (past sounds don't arrive)

The third is the nature of events itself. A shout doesn't linger.

Choosing the target

NetworkEventTarget offers three choices.

Target	Who runs it	Where it fits
All	Everyone including you	Chimes, fireworks, buzzers
Others	Everyone but you	When you want to play yours locally first
Owner	That object's owner	When you're asking the owner to do something

Situations for Others are limited: when you want your own to play instantly, without waiting for a network round trip. In that case, you call your own.

Owner gets used differently. Because of the constraint that only the owner can write synced variables, someone other than the owner who wants to change state asks the owner to.

// Ask the owner to add to the score
SendCustomNetworkEvent(NetworkEventTarget.Owner, nameof(AddScore));

For logic where losing an update matters, like adding to a score, having the owner alone accept and process it is more dependable than everyone writing freely. For ownership, see understanding ownership.

Common Pitfalls

• Only you hear it → You're calling the method directly instead of SendCustomNetworkEvent
• Nobody hears it → Check that [NetworkCallable] is attached and the method is public
• The sound plays twice → You sent to All and also called the method yourself
• A sync mode error appears → Network events can't be sent with BehaviourSyncMode.None. Use Manual
• Ringing from a UI button only affects you → The button's On Click connects to the sending method. Connecting it directly to the receiving method runs it only for the presser

Bonus: Good to Know Up Front

• Handle rapid presses: Sending a flood of events in a short time congests the connection and affects other synchronization. Blocking by elapsed time since the last one is the easy route

• Arguments can be passed: Network events can carry values. There are limits on count and type, though, so complex data is more dependable held in synced variables
• Combine with state: "Open the door" as a synced variable and "the opening sound" as an event is the practical combination. Split by role
• Delivery isn't guaranteed: Depending on network conditions, an event may not arrive. Fine for sound effects, but avoid relying on events alone for anything that drives progression
• It's useful all over: A quiz's correct-answer buzzer, an event venue's start signal, a game's start countdown, an applause effect. All "just in the moment" logic

Summary

Network Events are a mechanism for having everyone present run some logic.

• State that persists is a synced variable; a cue in the moment is an event
• Send a public method marked [NetworkCallable], specified with nameof
• All includes you. Calling it yourself too doubles it
• It doesn't reach late joiners

The question to ask before using one is: "Should someone arriving later know about this?" No means an event.

To share a held object's position, go to VRC Object Sync. To keep a setting until next time, go to saving volume with PlayerData.