Martin Professional Extube, User Manual

Page: 23 / 48

Control data link 23
Control data link
Extube fixtures must be connected via a data link to allow DMX control.
The following considerations must be taken into account when planning
the data link:
• RS-485 data cable designed for exterior use is required for outdoor
installations. RS-485 cable has low capacitance and a characteristic
impedance of 85 to 150 Ohms. It is electrically shielded and has at least
1 twisted pair of conductors. The minimum recommended wire size is
0.25 mm
2
(24 AWG) for runs up to 300 meters (1000 ft.) and 0.32 mm
2
(22 AWG) for runs up 500 meters (1640 ft). CAT 5e network cable
designed for direct burial can be used in outdoor installations, but you
are recommended to run it inside conduit.
• CAT 5e network cable is suitable for the control data link in indoor
installations. Installation-type cable is acceptable for fixed installations.
Flexible patch-type cable with good bend and torsion recovery is
required in movable installations (Martin patch cables are
recommended).
• Long parallel runs of AC power and control data cables may cause
interference on the data link and must be avoided. Even if not required
by law, use separate conduits for power and data cables.
• The maximum permitted control data cable length before a control
signal amplifier is required is 500 meters (1640 ft.). An optically isolated
amplifier-splitter such as the Martin™ RS-485 Opto-Splitter™ (P/N
90758060) must be used to extend a link beyond this length.
• If you want to control more than one single line of interconnected
Extubes, you must either use one DMX output from your controller for
each line of fixtures or use an optically isolated amplifier-splitter to split
the data link into one branch for each line of Extubes. The Martin
RS-485 Opto-Splitter allows you to split a link into four branches.
• Each link or branch of a link must be terminated by installing an end cap
on the last fixture.
• One DMX universe has 512 DMX control channels available. If
individual control of the fixtures in an installation is required, each
fixture must be given its own channels until the limit of 512 is reached.
At this point, a new DMX universe must be created.
• The number of fixtures that can be individually controlled in one DMX
universe depends on the number of DMX channels they use. if Extubes
are set to HSI mode, for example, each fixture requires 3 DMX
channels. The total number of Extubes that can be linked in one DMX
universe will therefore be 512/3 = 170.
When planning DMX cable layout, remember that the maximum
current-carrying capacity of cables and fixtures limits the length of the line