Why doesn't my Niagara Data Channel writer with fixed emitter write?

Fixed-emitter writers need System Stage NDC Write configured in the system, not the emitter. Spawn-based emitters use Emitter Stage NDC Write.

System Stage vs Emitter Stage?

System Stage runs once per frame at system level; suitable for fixed events (player position broadcast). Emitter Stage runs per-particle in spawn/update; for per-particle events.

Writer system Tick Group must precede reader system. Default During Physics; set writer to PrePhysics, reader to PostPhysics for clean ordering.

Fix: Niagara Data Channel Fixed Emitter Won't Write

Quick answer: Fixed-emitter writes go in System Stage. Tick group ordering: writer PrePhysics, reader PostPhysics.

System uses NDC to broadcast player position to other systems. Fixed emitter has Write to NDC module; reader sees nothing. System Stage was missing.

The Fix

Niagara System (writer):
  Tick Group:                 PrePhysics
  System Stage:
    + Write to NDC
        Channel:              SharedChannel
        Payload:              PlayerPosition

Niagara System (reader):
  Tick Group:                 PostPhysics
  Particle Spawn:
    + Read from NDC (same Channel)

System Stage runs at system level; right place for fixed-rate event broadcasts. Emitter Stage is for per-particle events.

Verifying

Reader emitter sees writer's payload. Niagara Debugger shows non-zero entries on the channel.

“System Stage. Tick order. NDC flows.”

Related Issues

For NDC writer reader, see data channels. For Stateless emitter, see stateless.

System Stage. Tick order.