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Serial LED

This manual explains how to use the Serial LED functionality to drive serial LED strips (e.g. WS2812 / similar) from an ELC NodeGBx 8 or NodeHD 24 output.

What “Serial LED” Means

Certain addressable LED strips (e.g. WS2812-type) accept a single-ended data input (often labeled DI).
The Node8GBx can output a signal that can be used to drive these strips using an XLR-5 output, either:

  • Directly (short cable run, “Basic method”), or
  • Via an RS485 receiver near the strip (long cable run, “Advanced method”).

Basic Method (Short cable run)

When to use

Use this method when the distance between the Node output and the start of the LED strip is only a couple of meters.

Wiring (XLR-5 from Node → LED strip)

Connect the Node’s XLR-5 output to the LED strip input as follows:

  • XLR Pin 1 (GND) → LED strip GND
  • XLR Pin 2 (data −) → LED strip DI (data input)
  • XLR Pin 3 (data +) → NOT connected

Power and grounding (critical)

  • Power the LED strip from an external +5V supply (or the strip’s required voltage, if applicable to your strip type).
  • All grounds must be tied together:
  • LED strip GND
  • Power supply GND
  • Node XLR Pin 1 (GND)

If the grounds are not common, the data signal will be unreliable.

Advanced Method (Long cable run)

When to use

Use this method when you need a longer cable run between the node and the LED strip—up to normal DMX cable length.

This enables: - Centralized nodes - Distributed LED strips + PSUs - A robust differential link over long cable, then conversion back to a single-ended data signal near the strip.

Principle

You run a differential pair from the Node output to a receiver/driver IC mounted close to the LED strip, then feed the strip’s DI from the IC.

Common suitable ICs: - MAX485 - SN75176 (Any compatible RS485 transceiver with a receiver output can work similarly.)

Cable and termination

  • Use a 110Ω twisted pair (typical DMX cable type).
  • The application note shows a run up to 300 m with 110Ω termination at the receiver end.

Place a 110Ω resistor between A and B at the RS485 receiver/transceiver near the LED strip.

Wiring (Node XLR-5 → RS485 → LED strip)

Node XLR-5 to RS485 A/B

  • XLR Pin 1 (GND) → RS485 GND (and PSU/strip ground)
  • XLR Pin 2 (data −) → RS485 A
  • XLR Pin 3 (data +) → RS485 B

Note from the application note: DMX data + is connected to B.

RS485 to LED strip

  • RS485 RO (Receiver Output) → LED strip DI
  • RS485 VCC → +5V (external supply)
  • RS485 GND → GND (external supply + LED strip ground)

To use the transceiver as a receiver only (common approach in this topology): - Keep receiver enabled and driver disabled. - Depending on chip pin naming: - /RE typically LOW = receiver enabled - DE typically LOW = driver disabled

(Exact logic depends on the specific IC—confirm with the datasheet.)

Power and grounding (still critical)

Even with RS485, you still must ensure: - Node GND (XLR pin 1), - PSU GND, and - LED strip GND are all connected together.

Basic method checklist

  • Distance node → strip is only a couple meters
  • XLR pin 1 → strip GND
  • XLR pin 2 → strip DI
  • XLR pin 3 not connected
  • PSU GND, strip GND, XLR pin 1 are common

Advanced method checklist

  • RS485 transceiver mounted near the LED strip
  • Twisted pair cable (DMX type) used for the long run
  • XLR pin 2 → A, XLR pin 3 → B
  • 110Ω termination between A and B at receiver end
  • RS485 RO → strip DI
  • RS485 VCC = +5V, RS485 GND common with strip + PSU + node
  • Receiver enabled, driver disabled (per IC datasheet)

Troubleshooting Tips

Symptoms: flicker, random colors, intermittent control

  • Check common ground between node, PSU, and strip (most common cause).
  • For long runs, switch to the Advanced method with RS485 near the strip.
  • Ensure the termination resistor is installed (advanced method).
  • Verify A/B polarity (especially the note: data+ → B).

Symptoms: no response at all

  • Confirm LED strip power (+5V and GND).
  • Confirm you are connected to the strip’s DI (not DO).
  • Confirm the RS485 IC has power (+5V on VCC) and correct enable states.