12.2. Building a Serial DMX Chain
DMX xtures are designed to receive data through a serial Daisy Chain. A Daisy Chain
connection is where the DATA OUT of one xture connects to the DATA IN of the next
xture. The order in which the xtures are connected is not important and has no effect
on how a controller communicates to each xture. Use an order that provides for the
easiest and most direct cabling.
DMX Terminator
CHAIN
Connect xtures using shielded 2-conductor twisted pair cable with 3-pin XLR male to
female connectors. The shield connection is pin 1, while pin 2 is Data Negative (S-), and
pin 3 is Data positive (S+).
DMX use of XLR connectors
1 = Ground / Shield
2 = DMX +
3 = DMX -
INPUT OUTPUT
CAUTION: Wires must not come into contact with each other; otherwise the
xtures will not work at all, or will not work properly.
12.3. DMX Terminator
DMX is a resilient communication protocol, however errors still occasionally occur.
In order to prevent electrical noise from disturbing and corrupting the DMX control
signals, a good habit is to connect DMX output of last xture in the chain to a DMX
terminator, especially over long signal cable runs.
The DMX terminator is simply an XLR connector with a 120Ω (ohm), 1/4 Watt resistor
connected across Signal (-) and Signal (+), respectively, pins 2 and 3, which is then
plugged into the output socket on last projector in the chain. The connections are
illustrated below.
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