100 Metres Between Units. Not One.
Plain SPI pixel data stays reliable for about a metre. SPI Lamp 2 carries a differential signal over ordinary Cat5e instead, so the distance between units is measured in tens of metres rather than in centimetres.
The Protocol
Why the distance changes
The link between units runs a custom LSS strip 2 protocol at 2.5 Mbps. It is differential, meaning the signal is carried as the difference between two wires, which is what makes it shrug off the interference that ruins a long single-ended SPI run.
Both ports are ESD protected and carry Data+, Data- and ground on a standard non-shielded RJ-45. Cat5e or better is all the cable it needs.
- Custom LSS strip 2 protocol at 2.5 Mbps
- Differential signalling on Data+ and Data-
- Up to 100 m of Cat5e between two units
- ESD protection on both ports
One Warning
These ports are not Ethernet
The connector is the only thing SPI Lamp 2 shares with a computer network. The pinout, the voltages, the speed and the protocol are all different from 10, 100 or 1000 Mbps Ethernet.
Never plug a unit into a network card, switch or router. Use the RJ-45 ports only for unit to unit links and for the feed from the controller.
- Never connect a unit to a network switch or router
- Different pinout, voltage, speed and protocol from Ethernet
- RJ-45 is used only for the connector, not the network
- Feed comes from an LEC3 or SPI Matrix SPI output
FAQ
Long, Robust Cable Runs questions
Up to 100 metres of Cat5e or better between each pair of units.
No. The ports use a different pinout, voltage, speed and protocol from Ethernet, and connecting them to network equipment can damage the device.
Standard non-shielded Cat5e or better, terminated as normal RJ-45 patch cable. More in Choosing Cables for an LED Project.
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