LSC Lighting ISOnode - Manual (Page 9)

LSC Lighting Systems (Aust) Pty Ltd Page 8
ISOseries Installation guide
3.0 Cable Selection
The performance of any DMX network is directly related to the quality of cable chosen to
convey the DMX information. DMX512 has a moderate data transmission rate of 250 Kbits/s,
and therefore requires selection of a cable that does not significantly distort the signal or give
rise to signal reflections.
Typical characteristics for a good DMX network cable include;
• Twisted pair with Nominal impedance of 100-120 ohms.
• low
capacitance.
• Fully encased with braid and foil shielding.
• Conforms to EIA 485 requirements.
When using a single cable to carry +24VDC power and DMX data, it is important to select a
cable that has been specifically designed for this purpose. DMX data conductors should be
internally shielded from the power conductors and the power conductors (+24V and Ground
return) in the cable must also be suitably sized to carry the current from the ISOPOWER/s to
all connected DMX devices.
Cables used with audio systems are not suitable for DMX512 networks as they typically have
higher capacitance, incorrect characteristic impedance and minimal shielding. At DMX512
data rates this can cause bit time distortion and signal reflections/overshoot.