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I would like to connect multiple devices using DMX512 protocol. I would like to use the same cable for both power (12V, each device draws around 10W) and communication. For power I need 2 wires and for DMX512 I need 3 wires (Sig+, Sig-, GND).

Generally, a 5 wire cable would do the trick but my question, could this also work with 4 wires were Power GND and DMX512 GND share the same wire?

Power supply is a 'good' switchable PSU and the end devices are LED drivers so I don't expect any spikes, transients, sags or other power 'artifacts'.

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  • \$\begingroup\$ DMX512 is not a very robust form of communications so I would want to use a screened/shielded cable and four inner conductors. \$\endgroup\$ – Andy aka Jan 11 '18 at 9:43
  • \$\begingroup\$ When saying "four inner conductors" I understand that you would use one conductor for power GND and data GND. Is this correct? \$\endgroup\$ – Gilad Mar 13 '18 at 13:24
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DMX512 is electrically RS485, so you have the usual common mode range restrictions inherent to that standard (+12 -7V IIRC).

I would want to do some experiments before going there as performance will depend on just how noisy the loads are, some led drivers can be pretty horrible for PWM switching noise getting onto the supply cables.

You will probably find that line termination helps, as does some LC filtering of the power at each node, but really you need to get 'the scope out and have a look.

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