Martin PDE Junction Box / Break-In / Break-Out Cable user guide
13
Data connection to Active Junction Box using DMX512
In a DMX-controlled system, an RDM-compliant DMX lighting controller sends a DMX control
data signal over a DMX link to the Junction Boxes of the system, and then over the hybrid link to
the fixtures.
The Active Junction box contains an active DMX/RDM splitter, so the Hybrid PDE output is
completely isolated from the DMX In & Thru ports. This means that the Active Junction box
counts as a single DMX/RDM device on the DMX line coming from the lighting console,
regardless the amount of fixtures connected to its PDE output.
The DMX In & Thru ports are hardwired to each other. So even if the Active Junction Box loses
power, it will relay data between the two XLR connectors.
The DMX link requires DMX cable. It can be a maximum 300 m (1000 ft.) in length (measured
between lighting console, DMX node or DMX splitter and last Active Junction Box on the chain)
and must run in one single daisy-chain, but it can be extended or split into branches using an
RDM-compliant amplifier/splitter. Alternatively, you can run the DMX signal from the controller
over Ethernet cable using Art-Net protocol and convert it to a DMX-compliant signal with an Art-
Net to DMX converter.
For reliable DMX and RDM data transfer, it is recommended to terminate each branch with a
termination plug – this contains a 120 ohm resistor between the cold and hot DMX data lines
(pins 2 and 3 on XLR5, pins 4 and 7 on PDE connector). This means that both an unused DMX
thru port on the Active Junction Box as well as the female PDE connector of the last fixture on a
chain need to be fitted with such a termination plug.
The total length of Hybrid PDE cables combined must not exceed 300 m (measured between
Active Junction Box and last fixture on the chain).
If you would like assistance with creating a DMX link, your Martin® supplier will be glad to advise.
The number of fixtures that you can control on one DMX link is limited by the number of DMX
channels each fixture will use and the 512 DMX channels available in one DMX universe at the
DMX controller. Each time you have used 512 channels, you must create a new DMX link that is
connected to a new DMX universe on the controller. Note that this limit applies to the DMX link.
The maximum safety limits that apply to the chain of fixtures and cable (see “Safety limits for
connecting devices” on page 12) take priority and must be respected in all cases.
DMX512 data is connected to the junction box using the XLR5 connector. The pin-out is:
x
pin 1 = shield
x
pin 2 = cold (-)
x
pin 3 = hot (+)
(this example shows the VDO
Atomic Bold and VDO Atomic
Dot fixtures, but any mix of
Martin products with PDE
interface can be used)
