IBUS (digital UART)

IBUS is FlySky’s digital RC protocol. Magic Box outputs it on the UART 3.5 mm jack (and on the dedicated UART pads on the motherboard), same physical pinout as SBUS — only the wire format and baud differ.

Wire format: non-inverted UART, 115 kbps, 8N1. Up to 14 channels per frame. Lighter and slower than SBUS.

Pick IBUS when the FlySky TX module you’re driving lists IBUS on its signal input. Like PPM, SBUS and CRSF, this setting describes one thing only: the wire between Magic Box and your module. What happens after that — the RF link, your receiver, your model — is the module’s business, not Magic Box’s.

Check the module’s spec sheet first. IBUS is FlySky’s own protocol, so FlySky modules are where to look — but not every one of them takes it. The FRM303 does not: its input is PPM, S.BUS or UART, and it has no setting to change that (details). Drive that one with PPM.

If your module takes SBUS as well, SBUS is the safer, more universal choice — and the only digital one that works on every Magic Box board.

Configure in the Web UI

1. Open the Web UI from your phone or laptop.
2. Go to Settings → Output protocol.
3. Pick IBUS.
4. Save. The change applies on next boot.

PPM keeps working at the same time on the PPM jack — you can drive both a digital receiver and a PPM trainer port simultaneously if your setup needs both.

Magic Box v1.4 + IBUS

v1.4’s UART is hardwired inverted, with no per-protocol switch. IBUS expects a non-inverted line, so on a v1.4 box IBUS will not work unless the module can be told to accept an inverted input, or you put an external signal inverter on the wire. Modules configured by buttons rather than a WebUI generally offer no such setting — which rules out most of them, the FRM303 included.

Use SBUS instead. Same jack, same cable, same module — and inverted is exactly what SBUS wants, so v1.4 drives it natively with nothing to set on either end.

On v2.0 there’s no catch

v2.0 switches inversion in hardware per protocol, so IBUS goes out non-inverted per spec. Pick whatever your module accepts. Side-by-side: Hardware v1.4 vs v2.0.

Verify the chain

If your model uses a flight controller, its receiver tab is the boring default (iNav / Betaflight naming) — it reads what your receiver puts out, so which Magic Box board you own doesn’t come into it:

• Receiver type: SERIAL
• Serial Receiver Provider: IBUS
• Serial Port Inverted: OFF
• Serial receiver half-duplex: OFF

Once it’s set, the receiver tab fills in with channel bars on a healthy link — same as in the SBUS verification screenshots, just with IBUS in the Provider dropdown.

If you don’t have a flight controller, plug the receiver into a servo and watch it move when you push the stick — same signal, different consumer.

Wiring

See External TX Modules for the stereo cable layout, the UART pad alternative, and power options — the same wiring patterns work for any digital protocol Magic Box outputs.

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• Most pilots want SBUS instead — it covers more receivers and FCs by default.
• Running an ExpressLRS or Crossfire TX module? See CRSF.
• Want the analog path? See PPM.