Setup
7
Tips for building a serial link
• Use shielded twisted-pair cable designed for RS-485 devices: standard microphone cable cannot transmit DMX data
reliably over long runs. For links up to 300 meters (1000 ft.) long, you can use 24 AWG, low capacitance, 85-150 ohm
characteristic impedance, shielded cable with 1 or more twisted pairs. For runs up to 500 meters (1640 ft.) use 22 AWG
cable. Use an amplifier if the serial link exceeds 500 meters.
• Never use a “Y” connector to split the link. To split the serial link into branches use a splitter such as the Martin 4-
Channel Opto-Isolated RS-485 Splitter/Amplifier.
• Do not overload the link. Up to 32 devices may be connected on a serial link.
• Terminate the link by installing a termination plug in the output socket of the last fixture on the link. The termination
plug, which is simply a male XLR connector with a 120 ohm, 0.25 watt resistor soldered between pins 2 and 3, “soaks
up” the control signal so it does not reflect back down the link and cause interference. If a splitter is used, terminate
each branch of the link.
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