DMX Wiring Guide: Cables, Pins, Termination

DMX wiring works when you follow a few RS‑485 rules: use the correct 120 Ω cable, wire the right pins, daisy‑chain your fixtures, and terminate the line. This guide focuses on the wiring mistakes that cause flicker and dropouts.

Step 1: Use proper DMX cable

Short answer: DMX needs 110–120 Ω twisted‑pair cable, not microphone cable.

Microphone cable usually has the wrong impedance and higher capacitance, which causes reflections and data errors over longer runs.

More detail: DMX cables in practice.

Step 2: Wire the correct pinout

Short answer: pin 1 = shield/ground, pin 2 = data‑, pin 3 = data+.

For 3‑pin XLR, the first three pins map directly to 5‑pin DMX. See 3‑pin vs 5‑pin XLR for DMX.

Step 3: Daisy‑chain instead of passive splitting

Short answer: DMX is a bus, not an audio split.

• Controller → fixture → fixture → fixture
• Use active splitters for branches

Guidance: DMX splitters and opto‑isolation.

Step 4: Terminate the last fixture

Short answer: add a 120 Ω terminator at the last fixture to stop reflections.

Field guide: DMX cable & termination field guide.

How long can a DMX run be?

Short answer: RS‑485 can reach long distances under ideal conditions, but real‑world lighting runs are shorter. Cable quality, connectors, and fixture electronics matter.

Use high‑quality cable and split long runs with opto‑isolated splitters rather than pushing a single line too far.

Common wiring mistakes (and fixes)

Short answer: most DMX wiring issues are cable or termination problems.

• Wrong cable: replace mic cable with DMX cable.
• Reversed polarity: swap data+ and data‑.
• No termination: add a terminator to the last fixture.
• Passive Y‑splits: use active splitters instead.

In practice: a clean wiring checklist

Short answer: a quick wiring checklist prevents most show‑day issues.

1. DMX cable confirmed (110–120 Ω).
2. Pinout verified on every adapter.
3. Daisy‑chain only, or active split.
4. Termination on the final device.